Skip to content
Projects
Groups
Snippets
Help
Loading...
Help
Support
Keyboard shortcuts
?
Submit feedback
Contribute to GitLab
Sign in
Toggle navigation
P
Postgres FD Implementation
Project overview
Project overview
Details
Activity
Releases
Repository
Repository
Files
Commits
Branches
Tags
Contributors
Graph
Compare
Issues
0
Issues
0
List
Boards
Labels
Milestones
Merge Requests
0
Merge Requests
0
CI / CD
CI / CD
Pipelines
Jobs
Schedules
Analytics
Analytics
CI / CD
Repository
Value Stream
Wiki
Wiki
Snippets
Snippets
Members
Members
Collapse sidebar
Close sidebar
Activity
Graph
Create a new issue
Jobs
Commits
Issue Boards
Open sidebar
Abuhujair Javed
Postgres FD Implementation
Commits
a8cb3368
Commit
a8cb3368
authored
Apr 07, 2003
by
Peter Eisentraut
Browse files
Options
Browse Files
Download
Email Patches
Plain Diff
General editing
parent
cb1d036a
Changes
8
Hide whitespace changes
Inline
Side-by-side
Showing
8 changed files
with
1388 additions
and
1710 deletions
+1388
-1710
doc/src/sgml/datetime.sgml
doc/src/sgml/datetime.sgml
+2
-2
doc/src/sgml/jdbc.sgml
doc/src/sgml/jdbc.sgml
+303
-299
doc/src/sgml/plperl.sgml
doc/src/sgml/plperl.sgml
+14
-10
doc/src/sgml/plpgsql.sgml
doc/src/sgml/plpgsql.sgml
+791
-1126
doc/src/sgml/plpython.sgml
doc/src/sgml/plpython.sgml
+39
-35
doc/src/sgml/pltcl.sgml
doc/src/sgml/pltcl.sgml
+179
-178
doc/src/sgml/pygresql.sgml
doc/src/sgml/pygresql.sgml
+22
-27
doc/src/sgml/xplang.sgml
doc/src/sgml/xplang.sgml
+38
-33
No files found.
doc/src/sgml/datetime.sgml
View file @
a8cb3368
<!--
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/datetime.sgml,v 2.3
0 2003/03/13 01:30:27
petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/datetime.sgml,v 2.3
1 2003/04/07 01:29:25
petere Exp $
-->
-->
<appendix id="datetime-appendix">
<appendix id="datetime-appendix">
...
@@ -210,7 +210,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/datetime.sgml,v 2.30 2003/03/13 01:30:27 pe
...
@@ -210,7 +210,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/datetime.sgml,v 2.30 2003/03/13 01:30:27 pe
</sect1>
</sect1>
<sect1>
<sect1
id="datetime-keywords"
>
<title>Date/Time Key Words</title>
<title>Date/Time Key Words</title>
<para>
<para>
...
...
doc/src/sgml/jdbc.sgml
View file @
a8cb3368
<!--
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/jdbc.sgml,v 1.4
3 2003/03/25 16:15:37
petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/jdbc.sgml,v 1.4
4 2003/04/07 01:29:25
petere Exp $
-->
-->
<chapter id="jdbc">
<chapter id="jdbc">
<title><acronym>JDBC</acronym> Interface</title>
<title><acronym>JDBC</acronym> Interface</title>
<note>
<title>Author</title>
<para>
Originally written by Peter T. Mount (<email>peter@retep.org.uk</email>),
the original author of the <acronym>JDBC</acronym> driver.
</para>
</note>
<para>
<para>
<acronym>JDBC</acronym> is a core <acronym>API</acronym> of Java 1.1 and later.
<acronym>JDBC</acronym> is a core <acronym>API</acronym> of Java 1.1 and later.
It provides a standard set of
It provides a standard set of
...
@@ -21,7 +13,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/Attic/jdbc.sgml,v 1.43 2003/03/25 16:15:37
...
@@ -21,7 +13,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/Attic/jdbc.sgml,v 1.43 2003/03/25 16:15:37
<para>
<para>
<productname>PostgreSQL</> provides a <firstterm>type
<productname>PostgreSQL</> provides a <firstterm>type
4</firstterm> <acronym>JDBC</acronym>
D
river. Type 4 indicates
4</firstterm> <acronym>JDBC</acronym>
d
river. Type 4 indicates
that the driver is written in Pure Java, and communicates in the
that the driver is written in Pure Java, and communicates in the
database system's own network protocol. Because of this, the driver
database system's own network protocol. Because of this, the driver
is platform independent; once compiled, the driver can be used on
is platform independent; once compiled, the driver can be used on
...
@@ -33,13 +25,17 @@ $Header: /cvsroot/pgsql/doc/src/sgml/Attic/jdbc.sgml,v 1.43 2003/03/25 16:15:37
...
@@ -33,13 +25,17 @@ $Header: /cvsroot/pgsql/doc/src/sgml/Attic/jdbc.sgml,v 1.43 2003/03/25 16:15:37
<acronym>JDBC</acronym> programming, but should help to get you
<acronym>JDBC</acronym> programming, but should help to get you
started. For more information refer to the standard
started. For more information refer to the standard
<acronym>JDBC</acronym> <acronym>API</acronym> documentation.
<acronym>JDBC</acronym> <acronym>API</acronym> documentation.
Also, take a look at the examples included with the source. The
Also, take a look at the examples included with the source.
basic example is used here.
</para>
</para>
<sect1 id="jdbc-setup">
<sect1 id="jdbc-setup">
<title>Setting up the <acronym>JDBC</acronym> Driver</title>
<title>Setting up the <acronym>JDBC</acronym> Driver</title>
<para>
This section describes the steps you need to take before you can
write or run programs that use the JDBC interface.
</para>
<sect2 id="jdbc-build">
<sect2 id="jdbc-build">
<title>Getting the Driver</title>
<title>Getting the Driver</title>
...
@@ -71,8 +67,8 @@ $Header: /cvsroot/pgsql/doc/src/sgml/Attic/jdbc.sgml,v 1.43 2003/03/25 16:15:37
...
@@ -71,8 +67,8 @@ $Header: /cvsroot/pgsql/doc/src/sgml/Attic/jdbc.sgml,v 1.43 2003/03/25 16:15:37
<para>
<para>
To use the driver, the JAR archive (named
To use the driver, the JAR archive (named
<filename>postgresql.jar</filename> if you built from source, otherwise
<filename>postgresql.jar</filename> if you built from source, otherwise
it will likely be named <filename>jdbc
7.2
-1.1.jar</filename> or
it will likely be named <filename>jdbc
&majorversion;
-1.1.jar</filename> or
<filename>jdbc
7.2
-1.2.jar</filename> for the JDBC 1 and JDBC 2 versions
<filename>jdbc
&majorversion;
-1.2.jar</filename> for the JDBC 1 and JDBC 2 versions
respectively)
respectively)
needs to be included in the
needs to be included in the
class path, either by putting it in the <envar>CLASSPATH</envar>
class path, either by putting it in the <envar>CLASSPATH</envar>
...
@@ -80,26 +76,18 @@ $Header: /cvsroot/pgsql/doc/src/sgml/Attic/jdbc.sgml,v 1.43 2003/03/25 16:15:37
...
@@ -80,26 +76,18 @@ $Header: /cvsroot/pgsql/doc/src/sgml/Attic/jdbc.sgml,v 1.43 2003/03/25 16:15:37
<command>java</command> command line.
<command>java</command> command line.
</para>
</para>
<para>
<para>
For instance, I have an application that uses the
For instance, assume we have an application that uses the
<acronym>JDBC</acronym> driver to access a large database
<acronym>JDBC</acronym> driver to access a database, and that
containing astronomical objects. I have the application and the
application is installed as
<acronym>JDBC</acronym> driver installed in the <filename
<filename>/usr/local/lib/myapp.jar</filename>. The PostgreSQL
class="directory">/usr/local/lib</filename> directory, and the
JDBC driver installed as
Java <acronym>JDK</acronym> installed in
<filename>/usr/local/pgsql/share/java/postgresql.jar</>. To run
<filename>/usr/local/jdk1.3.1</filename>. To run the
the application, we would use:
application, I would use:
<programlisting>
<programlisting>
export CLASSPATH=/usr/local/lib/
finder.jar<co id="co.jdbc-finder">
:/usr/local/pgsql/share/java/postgresql.jar:.
export CLASSPATH=/usr/local/lib/
myapp.jar
:/usr/local/pgsql/share/java/postgresql.jar:.
java
Finder
java
MyApp
</programlisting>
</programlisting>
<calloutlist>
<callout arearefs="co.jdbc-finder">
<para>
<filename>finder.jar</filename> contains the Finder application.
</para>
</callout>
</calloutlist>
</para>
</para>
<para>
<para>
...
@@ -109,7 +97,7 @@ java Finder
...
@@ -109,7 +97,7 @@ java Finder
</sect2>
</sect2>
<sect2 id="jdbc-prepare">
<sect2 id="jdbc-prepare">
<title>Preparing the Database for <acronym>JDBC</acronym></title>
<title>Preparing the Database
Server
for <acronym>JDBC</acronym></title>
<para>
<para>
Because Java only uses TCP/IP connections, the
Because Java only uses TCP/IP connections, the
...
@@ -125,14 +113,19 @@ java Finder
...
@@ -125,14 +113,19 @@ java Finder
Also, the client authentication setup in the
Also, the client authentication setup in the
<filename>pg_hba.conf</filename> file may need to be configured.
<filename>pg_hba.conf</filename> file may need to be configured.
Refer to <xref linkend="client-authentication"> for details. The
Refer to <xref linkend="client-authentication"> for details. The
<acronym>JDBC</acronym>
D
river supports the trust, ident,
<acronym>JDBC</acronym>
d
river supports the trust, ident,
password, md5, and crypt authentication methods.
password, md5, and crypt authentication methods.
</para>
</para>
</sect2>
</sect2>
</sect1>
</sect1>
<sect1 id="jdbc-use">
<sect1 id="jdbc-use">
<title>Using the Driver</title>
<title>Initializing the Driver</title>
<para>
This section describes how to load and initialize the JDBC driver
in your programs.
</para>
<sect2 id="jdbc-import">
<sect2 id="jdbc-import">
<title>Importing <acronym>JDBC</acronym></title>
<title>Importing <acronym>JDBC</acronym></title>
...
@@ -144,15 +137,15 @@ java Finder
...
@@ -144,15 +137,15 @@ java Finder
<programlisting>
<programlisting>
import java.sql.*;
import java.sql.*;
</programlisting>
</programlisting>
</para>
<
important
>
<
note
>
<para>
<para>
Do not import the <literal>org.postgresql</literal> package. If
Do not import the <literal>org.postgresql</literal> package. If
you do, your source will not compile, as
you do, your source will not compile, as
<command>javac</command> will get confused.
<command>javac</command> will get confused.
</para>
</para>
</important>
</note>
</para>
</sect2>
</sect2>
<sect2 id="jdbc-load">
<sect2 id="jdbc-load">
...
@@ -175,6 +168,7 @@ Class.forName("org.postgresql.Driver");
...
@@ -175,6 +168,7 @@ Class.forName("org.postgresql.Driver");
This will load the driver, and while loading, the driver will automatically
This will load the driver, and while loading, the driver will automatically
register itself with <acronym>JDBC</acronym>.
register itself with <acronym>JDBC</acronym>.
</para>
<note>
<note>
<para>
<para>
...
@@ -183,7 +177,6 @@ Class.forName("org.postgresql.Driver");
...
@@ -183,7 +177,6 @@ Class.forName("org.postgresql.Driver");
not available.
not available.
</para>
</para>
</note>
</note>
</para>
<para>
<para>
This is the most common method to use, but restricts your code to
This is the most common method to use, but restricts your code to
...
@@ -250,7 +243,7 @@ jdbc:postgresql://<replaceable class="parameter">host</replaceable>:<replaceable
...
@@ -250,7 +243,7 @@ jdbc:postgresql://<replaceable class="parameter">host</replaceable>:<replaceable
</listitem>
</listitem>
</itemizedlist>
</itemizedlist>
where
:
The parametes have the following meanings
:
<variablelist>
<variablelist>
<varlistentry>
<varlistentry>
...
@@ -292,7 +285,7 @@ jdbc:postgresql://<replaceable class="parameter">host</replaceable>:<replaceable
...
@@ -292,7 +285,7 @@ jdbc:postgresql://<replaceable class="parameter">host</replaceable>:<replaceable
<para>
<para>
To connect, you need to get a <classname>Connection</classname> instance from
To connect, you need to get a <classname>Connection</classname> instance from
<acronym>JDBC</acronym>. To do this,
<acronym>JDBC</acronym>. To do this,
you
would
use the <function>DriverManager.getConnection()</function> method:
you use the <function>DriverManager.getConnection()</function> method:
<programlisting>
<programlisting>
Connection db = DriverManager.getConnection(url, username, password);
Connection db = DriverManager.getConnection(url, username, password);
...
@@ -336,8 +329,8 @@ db.close();
...
@@ -336,8 +329,8 @@ db.close();
column of each row using a <classname>Statement</classname>.
column of each row using a <classname>Statement</classname>.
<programlisting>
<programlisting>
Statement st = db.createStatement();
Statement st = db.createStatement();
ResultSet rs = st.executeQuery("SELECT * FROM mytable
where
columnfoo = 500");
ResultSet rs = st.executeQuery("SELECT * FROM mytable
WHERE
columnfoo = 500");
while(rs.next()) {
while
(rs.next()) {
System.out.print("Column 1 returned ");
System.out.print("Column 1 returned ");
System.out.println(rs.getString(1));
System.out.println(rs.getString(1));
}
}
...
@@ -347,15 +340,15 @@ st.close();
...
@@ -347,15 +340,15 @@ st.close();
</para>
</para>
<para>
<para>
This example
will issue the same query as before using
This example
issues the same query as before but uses
a <classname>PreparedStatement</classname>
a <classname>PreparedStatement</classname>
and a bind value in the query.
and a bind value in the query.
<programlisting>
<programlisting>
int foovalue = 500;
int foovalue = 500;
PreparedStatement st = db.prepareStatement("SELECT * FROM mytable
where
columnfoo = ?");
PreparedStatement st = db.prepareStatement("SELECT * FROM mytable
WHERE
columnfoo = ?");
st.setInt(1, foovalue);
st.setInt(1, foovalue);
ResultSet rs = st.executeQuery();
ResultSet rs = st.executeQuery();
while(rs.next()) {
while
(rs.next()) {
System.out.print("Column 1 returned ");
System.out.print("Column 1 returned ");
System.out.println(rs.getString(1));
System.out.println(rs.getString(1));
}
}
...
@@ -366,8 +359,7 @@ st.close();
...
@@ -366,8 +359,7 @@ st.close();
</example>
</example>
<sect2>
<sect2>
<title>Using the <classname>Statement</classname> or <classname>
<title>Using the <classname>Statement</classname> or <classname>PreparedStatement</classname> Interface</title>
PreparedStatement</classname> Interface</title>
<para>
<para>
The following must be considered when using the
The following must be considered when using the
...
@@ -463,10 +455,10 @@ st.close();
...
@@ -463,10 +455,10 @@ st.close();
<para>
<para>
<classname>ResultSet</classname> is currently read only.
<classname>ResultSet</classname> is currently read only.
You can not update data through the <classname>ResultSet</classname>.
You can not update data through the <classname>ResultSet</classname>.
If you want to update data you need to do it the
old fashioned
way
If you want to update data you need to do it the
normal
way
by
issuing a <acronym>SQL</acronym> update statement
. This is
by
using the <acronym>SQL</acronym> statement <command>UPDATE</command>
. This is
in conformance with the <acronym>JDBC</acronym> specification
in conformance with the <acronym>JDBC</acronym> specification
which does not require drivers to provide
this functionality
.
which does not require drivers to provide
updatable result sets
.
</para>
</para>
</listitem>
</listitem>
</itemizedlist>
</itemizedlist>
...
@@ -478,23 +470,25 @@ st.close();
...
@@ -478,23 +470,25 @@ st.close();
<title>Performing Updates</title>
<title>Performing Updates</title>
<para>
<para>
To change data (perform an insert, update, or delete)
To change data (perform an <command>INSERT</command>,
you use the <function>executeUpdate()</function> method.
<command>UPDATE</command>, or <command>DELETE</command>) you use
<function>executeUpdate()</function> is similar to the
the <function>executeUpdate()</function> method. This method is
<function>executeQuery()</function> used to issue a select,
similar to the method <function>executeQuery()</function> used to
however it doesn't return a <classname>ResultSet</classname>,
issue a <command>SELECT</command> statement, but it doesn't return
instead it returns the number of records affected by the insert,
a <classname>ResultSet</classname>; instead it returns the number
update, or delete statement.
of rows affected by the <command>INSERT</command>,
<command>UPDATE</command>, or <command>DELETE</command> statement.
<xref linkend="jdbc-delete-example"> illustrates the usage.
</para>
</para>
<example id="jdbc-delete-example">
<example id="jdbc-delete-example">
<title>
Simple Delete Example
</title>
<title>
Deleting Rows in <acronym>JDBC</acronym>
</title>
<para>
<para>
This example will issue a simple
delete and print out the number
This example will issue a simple
<command>DELETE</command>
of rows deleted.
statement and print out the number
of rows deleted.
<programlisting>
<programlisting>
int foovalue = 500;
int foovalue = 500;
PreparedStatement st = db.prepareStatement("DELETE FROM mytable
where
columnfoo = ?");
PreparedStatement st = db.prepareStatement("DELETE FROM mytable
WHERE
columnfoo = ?");
st.setInt(1, foovalue);
st.setInt(1, foovalue);
int rowsDeleted = st.executeUpdate();
int rowsDeleted = st.executeUpdate();
System.out.println(rowsDeleted + " rows deleted");
System.out.println(rowsDeleted + " rows deleted");
...
@@ -509,19 +503,19 @@ st.close();
...
@@ -509,19 +503,19 @@ st.close();
<para>
<para>
To create, modify or drop a database object like a table or view
To create, modify or drop a database object like a table or view
you use the <function>execute()</function> method.
you use the <function>execute()</function> method.
This method is
<function>execute</function> is similar to the
similar to the method <function>executeQuery()</function>, but it
<function>executeQuery()</function> used to issue a select,
doesn't return a result. <xref linkend="jdbc-drop-table-example">
however it doesn't return a result
.
illustrates the usage
.
</para>
</para>
<example id="jdbc-drop-table-example">
<example id="jdbc-drop-table-example">
<title>Drop
Table Example
</title>
<title>Drop
ping a Table in JDBC
</title>
<para>
<para>
This example will drop a table.
This example will drop a table.
<programlisting>
<programlisting>
Statement st = db.createStatement();
Statement st = db.createStatement();
ResultSet rs = st.executeQuery
("DROP TABLE mytable");
st.execute
("DROP TABLE mytable");
st.close();
st.close();
</programlisting>
</programlisting>
</para>
</para>
...
@@ -534,11 +528,10 @@ st.close();
...
@@ -534,11 +528,10 @@ st.close();
<para>
<para>
<application>PostgreSQL</application> provides two distinct ways to
<application>PostgreSQL</application> provides two distinct ways to
store binary data. Binary data can be stored in a table using
store binary data. Binary data can be stored in a table using
<application>PostgreSQL's</application> binary data type
the data type <type>bytea</type> or by using the Large Object
<type>bytea</type>, or by using the <firstterm>Large Object</firstterm>
feature which stores the binary data in a separate table in a special
feature which stores the binary data in a separate table in a special
format
,
and refers to that table by storing a value of type
format and refers to that table by storing a value of type
<type>
OID
</type> in your table.
<type>
oid
</type> in your table.
</para>
</para>
<para>
<para>
...
@@ -547,32 +540,32 @@ st.close();
...
@@ -547,32 +540,32 @@ st.close();
<type>bytea</type> data type is not well suited for storing very
<type>bytea</type> data type is not well suited for storing very
large amounts of binary data. While a column of type
large amounts of binary data. While a column of type
<type>bytea</type> can hold up to 1 GB of binary data, it would
<type>bytea</type> can hold up to 1 GB of binary data, it would
require a huge amount of memory
(<acronym>RAM</acronym>)
to
require a huge amount of memory to
process such a large value. The Large Object method for
process such a large value. The Large Object method for
storing binary data is better suited to storing very large values,
storing binary data is better suited to storing very large values,
but it has its own limitations. Specifically deleting a row
but it has its own limitations. Specifically deleting a row
that contains a Large Object does not delete the Large Object.
that contains a Large Object
reference
does not delete the Large Object.
Deleting the Large Object is a separate operation that needs to
Deleting the Large Object is a separate operation that needs to
be performed. Large Objects also have some security
be performed. Large Objects also have some security
issues since anyone connected to the database ca
se
view
issues since anyone connected to the database ca
nn
view
and/or modify any Large Object, even if they don't have
and/or modify any Large Object, even if they don't have
permissions to view/update the row containing the Large Object.
permissions to view/update the row containing the Large Object
reference
.
</para>
</para>
<para>
<para>
7.2 is the first release of the <acronym>JDBC</acronym> D
river
Version 7.2 was the first release of the <acronym>JDBC</acronym> d
river
that supports the <type>bytea</type> data type. The introduction of
that supports the <type>bytea</type> data type. The introduction of
this functionality in 7.2 has introduced a change in behavior
this functionality in 7.2 has introduced a change in behavior
as compared to previous releases.
In 7.2
the methods
as compared to previous releases.
Since 7.2,
the methods
<function>getBytes()</function>, <function>setBytes()</function>,
<function>getBytes()</function>, <function>setBytes()</function>,
<function>getBinaryStream()</function>, and
<function>getBinaryStream()</function>, and
<function>setBinaryStream()</function> operate on
<function>setBinaryStream()</function> operate on
the <type>bytea</type> data type. In 7.1 these methods operated
the <type>bytea</type> data type. In 7.1
and earlier,
these methods operated
on the <type>
OID
</type> data type associated with Large Objects.
on the <type>
oid
</type> data type associated with Large Objects.
It is possible to revert the driver back to the old 7.1 behavior
It is possible to revert the driver back to the old 7.1 behavior
by setting the
<parameter>compatible</parameter> property
on
by setting the
property <literal>compatible</literal>
on
the <classname>Connection</classname>
to a value of
the <classname>Connection</classname>
object to the value
<literal>7.1</literal>
<literal>7.1</literal>
.
</para>
</para>
<para>
<para>
...
@@ -584,39 +577,44 @@ st.close();
...
@@ -584,39 +577,44 @@ st.close();
<para>
<para>
To use the Large Object functionality you can use either the
To use the Large Object functionality you can use either the
<classname>LargeObject</classname>
<acronym>API</acronym>
<classname>LargeObject</classname>
class
provided by the <application>PostgreSQL</application>
provided by the <application>PostgreSQL</application>
<acronym>JDBC</acronym>
D
river, or by using the
<acronym>JDBC</acronym>
d
river, or by using the
<function>getBLOB()</function> and <function>setBLOB()</function>
<function>getBLOB()</function> and <function>setBLOB()</function>
methods.
methods.
</para>
</para>
<important>
<important>
<para>
<para>
For <application>PostgreSQL</application>, you must access Large
You must access Large Objects within an <acronym>SQL</acronym>
Objects within an <acronym>SQL</acronym> transaction. You would
transaction block. You can start a transaction block by calling
open a transaction by using the
<function>setAutoCommit(false)</function>.
<function>setAutoCommit()</function> method with an input
parameter of <literal>false</literal>.
</para>
</para>
</important>
</important>
<note><para>In a future release of the
<note>
<acronym>JDBC</acronym> Driver, the <function>getBLOB()</function>
<para>
In a future release of the
<acronym>JDBC</acronym> driver, the <function>getBLOB()</function>
and <function>setBLOB()</function> methods may no longer
and <function>setBLOB()</function> methods may no longer
interact with Large Objects and will instead work on
interact with Large Objects and will instead work on
the data type
<type>bytea</type>
data types
. So it is recommended that you
<type>bytea</type>. So it is recommended that you
use the <classname>LargeObject</classname> <acronym>API</acronym>
use the <classname>LargeObject</classname> <acronym>API</acronym>
if you intend to use Large Objects.
if you intend to use Large Objects.
</para></note>
</para>
</note>
<para>
<xref linkend="jdbc-binary-data-example"> contains some examples on
how to process binary data using the PostgreSQL JDBC driver.
</para>
<example id="jdbc-binary-data-example">
<example id="jdbc-binary-data-example">
<title>
Binary Data Examples
</title>
<title>
Processing Binary Data in JDBC
</title>
<para>
<para>
For example, suppose you have a table containing the file name of
For example, suppose you have a table containing the file name
s
of
an image
and you also want to store the image in a <type>bytea</type>
images
and you also want to store the image in a <type>bytea</type>
column:
column:
<programlisting>
<programlisting>
CREATE TABLE images (imgname text, img bytea);
CREATE TABLE images (imgname text, img bytea);
...
@@ -649,13 +647,13 @@ fis.close();
...
@@ -649,13 +647,13 @@ fis.close();
<classname>Statement</classname> class can equally be used.)
<classname>Statement</classname> class can equally be used.)
<programlisting>
<programlisting>
PreparedStatement ps = con.prepareStatement("SELECT img FROM images WHERE imgname
=
?");
PreparedStatement ps = con.prepareStatement("SELECT img FROM images WHERE imgname
=
?");
ps.setString(1, "myimage.gif");
ps.setString(1, "myimage.gif");
ResultSet rs = ps.executeQuery();
ResultSet rs = ps.executeQuery();
if (rs != null) {
if (rs != null) {
while(rs.next()) {
while
(rs.next()) {
byte[] imgBytes = rs.getBytes(1);
byte[] imgBytes = rs.getBytes(1);
// use the
stream
in some way here
// use the
data
in some way here
}
}
rs.close();
rs.close();
}
}
...
@@ -674,76 +672,76 @@ ps.close();
...
@@ -674,76 +672,76 @@ ps.close();
the <classname>LargeObject</classname> <acronym>API</acronym> to
the <classname>LargeObject</classname> <acronym>API</acronym> to
store the file:
store the file:
<programlisting>
<programlisting>
CREATE TABLE images
LO (imgname text, imgOID OID
);
CREATE TABLE images
lo (imgname text, imgoid oid
);
</programlisting>
</programlisting>
</para>
</para>
<para>
<para>
To insert an image, you would use:
To insert an image, you would use:
<programlisting>
<programlisting>
// All LargeObject API calls must be within a transaction
// All LargeObject API calls must be within a transaction
block
conn.setAutoCommit(false);
conn.setAutoCommit(false);
// Get the Large Object Manager to perform operations with
// Get the Large Object Manager to perform operations with
LargeObjectManager lobj = ((org.postgresql.PGConnection)conn).getLargeObjectAPI();
LargeObjectManager lobj = ((org.postgresql.PGConnection)conn).getLargeObjectAPI();
//
c
reate a new large object
//
C
reate a new large object
int oid = lobj.create(LargeObjectManager.READ | LargeObjectManager.WRITE);
int oid = lobj.create(LargeObjectManager.READ | LargeObjectManager.WRITE);
//
open the large object for write
//
Open the large object for writing
LargeObject obj = lobj.open(oid, LargeObjectManager.WRITE);
LargeObject obj = lobj.open(oid, LargeObjectManager.WRITE);
// Now open the file
// Now open the file
File file = new File("myimage.gif");
File file = new File("myimage.gif");
FileInputStream fis = new FileInputStream(file);
FileInputStream fis = new FileInputStream(file);
//
c
opy the data from the file to the large object
//
C
opy the data from the file to the large object
byte buf[] = new byte[2048];
byte buf[] = new byte[2048];
int s, tl = 0;
int s, tl = 0;
while ((s = fis.read(buf, 0, 2048)) > 0)
while ((s = fis.read(buf, 0, 2048)) > 0) {
{
obj.write(buf, 0, s);
obj.write(buf, 0, s);
tl += s;
tl += s;
}
}
// Close the large object
// Close the large object
obj.close();
obj.close();
//
Now insert the row into imagesLO
//
Now insert the row into imageslo
PreparedStatement ps = conn.prepareStatement("INSERT INTO images
LO
VALUES (?, ?)");
PreparedStatement ps = conn.prepareStatement("INSERT INTO images
lo
VALUES (?, ?)");
ps.setString(1, file.getName());
ps.setString(1, file.getName());
ps.setInt(2, oid);
ps.setInt(2, oid);
ps.executeUpdate();
ps.executeUpdate();
ps.close();
ps.close();
fis.close();
fis.close();
</programlisting>
</programlisting>
</para>
</para>
<para>
<para>
Retrieving the image from the Large Object:
Retrieving the image from the Large Object:
<programlisting>
<programlisting>
// All LargeObject API calls must be within a transaction
// All LargeObject API calls must be within a transaction
block
conn.setAutoCommit(false);
conn.setAutoCommit(false);
// Get the Large Object Manager to perform operations with
// Get the Large Object Manager to perform operations with
LargeObjectManager lobj = ((org.postgresql.PGConnection)conn).getLargeObjectAPI();
LargeObjectManager lobj = ((org.postgresql.PGConnection)conn).getLargeObjectAPI();
PreparedStatement ps = con.prepareStatement("SELECT img
OID FROM imagesLO WHERE imgname=
?");
PreparedStatement ps = con.prepareStatement("SELECT img
oid FROM imageslo WHERE imgname =
?");
ps.setString(1, "myimage.gif");
ps.setString(1, "myimage.gif");
ResultSet rs = ps.executeQuery();
ResultSet rs = ps.executeQuery();
if (rs != null) {
if (rs != null) {
while(rs.next()) {
while
(rs.next()) {
//o
pen the large object for reading
// O
pen the large object for reading
int oid = rs.getInt(1);
int oid = rs.getInt(1);
LargeObject obj = lobj.open(oid, LargeObjectManager.READ);
LargeObject obj = lobj.open(oid, LargeObjectManager.READ);
//r
ead the data
// R
ead the data
byte buf[] = new byte[obj.size()];
byte buf[] = new byte[obj.size()];
obj.read(buf, 0, obj.size());
obj.read(buf, 0, obj.size());
//d
o something with the data read here
// D
o something with the data read here
// Close the object
// Close the object
obj.close();
obj.close();
}
}
rs.close();
rs.close();
}
}
...
@@ -2441,93 +2439,78 @@ public void unlink(int oid) throws SQLException
...
@@ -2441,93 +2439,78 @@ public void unlink(int oid) throws SQLException
<sect1 id="jdbc-thread">
<sect1 id="jdbc-thread">
<title>Using the
driver in a multithreaded or a servlet e
nvironment</title>
<title>Using the
Driver in a Multithreaded or a Servlet E
nvironment</title>
<para>
<para>
A problem with many <acronym>JDBC</acronym> drivers is that only
A problem with many <acronym>JDBC</acronym> drivers is that only
one thread can use a <classname>Connection</classname> at any one
one thread can use a <classname>Connection</classname> at any one
time -- otherwise a thread could send a query while another one is
time --- otherwise a thread could send a query while another one is
receiving results, and this would be a bad thing for the database
receiving results, and this could cause severe confusion.
engine.
</para>
</para>
<para>
<para>
The <productname>PostgreSQL</productname> <acronym>JDBC</acronym>
D
river
The <productname>PostgreSQL</productname> <acronym>JDBC</acronym>
d
river
is thread safe.
is thread safe.
Consequently, if your application uses multiple threads then you do
Consequently, if your application uses multiple threads then you do
not have to worry about complex algorithms to ensure that only one
not have to worry about complex algorithms to ensure that only one
thread
uses the database at a
ny
time.
uses the database at a time.
</para>
</para>
<para>
<para>
If a thread attempts to use the connection while another one is
If a thread attempts to use the connection while another one is
using it, it will wait until the other thread has finished its
using it, it will wait until the other thread has finished its
current operation. If
it
is a regular <acronym>SQL</acronym>
current operation. If
the operation
is a regular <acronym>SQL</acronym>
statement, then the operation consists of sending the statement and
statement, then the operation consists of sending the statement and
retrieving any <classname>ResultSet</classname> (in full). If it
retrieving any <classname>ResultSet</classname> (in full). If it
is a
<classname>Fastpath</classname>
call (e.g., reading a block
is a
fast-path
call (e.g., reading a block
from a
<classname>LargeObject</classname>) then it is the time to
from a
large object) then it consists of
send
and retrieve that block
.
send
ing and retrieving the respective data
.
</para>
</para>
<para>
<para>
This is fine for applications and applets but can cause a
This is fine for applications and applets but can cause a
performance problem with servlets. With servlets you can have a
performance problem with servlets. If you have several threads
heavy load on the connection. If you have several threads
performing queries then each but one will pause.
performing queries then each but one will pause, which may not be what
To solve this, you are advised to create a pool of connections.
you are after.
When ever a thread needs to use the database, it asks a manager
</para>
class for a <classname>Connection</classname> object. The manager
hands a free connection to the thread and marks it as busy. If a
<para>
free connection is not available, it opens one. Once the thread
To solve this, you would be advised to create a pool of
has finished using the connection, it returns it to the manager
connections. When ever a thread needs to use the database, it asks
which can then either close it or add it to the pool. The manager
a manager class for a <classname>Connection</classname>. The
would also check that the connection is still alive and remove it
manager hands a free connection to the thread and marks it as
from the pool if it is dead. The down side of a connection pool is
busy. If a free connection is not available, it opens one. Once
that it increases the load on the server because a new session is
the thread has finished with it, it returns it to the manager who
created for each <classname>Connection</classname> object. It is
can then either close it or add it to the pool. The manager would
up to you and your applications' requirements.
also check that the connection is still alive and remove it from
the pool if it is dead.
</para>
<para>
So, with servlets, it is up to you to use either a single
connection, or a pool. The plus side for a pool is that threads
will not be hit by the bottle neck caused by a single network
connection. The down side is that it increases the load on the
server, as a backend process is created for each
<classname>Connection</classname>. It is up to you and your
applications requirements.
</para>
</para>
</sect1>
</sect1>
<sect1 id="jdbc-datasource">
<sect1 id="jdbc-datasource">
<title>Connection Pools And DataSources</title>
<title>Connection Pools and Data Sources</title>
<sect2 id="jdbc-ds-version">
<title>JDBC, JDK Version Support</title>
<para>
<para>
JDBC 2 introduced standard connection pooling features in an
JDBC 2 introduced standard connection pooling features in an
add-on API known as the <acronym>JDBC</acronym> 2.0 Optional
add-on API known as the <acronym>JDBC</acronym> 2.0 Optional
Package (also known as the <acronym>JDBC</acronym> 2.0
Package (also known as the <acronym>JDBC</acronym> 2.0
Standard Extension). These features have since been included in
Standard Extension). These features have since been included in
the core JDBC 3 API. The <productname>PostgreSQL</productname>
the core JDBC 3 API. The <productname>PostgreSQL</productname>
<acronym>JDBC</acronym> drivers support these features with
<acronym>JDBC</acronym> drivers support these features
if it has been compiled
with
<acronym>JDK</acronym> 1.3.x in combination with the
<acronym>JDK</acronym> 1.3.x in combination with the
<acronym>JDBC</acronym> 2.0 Optional Package
<acronym>JDBC</acronym> 2.0 Optional Package
(<acronym>JDBC</acronym> 2), or with <acronym>JDK</acronym> 1.4
+
(<acronym>JDBC</acronym> 2), or with <acronym>JDK</acronym> 1.4
or higher
(<acronym>JDBC</acronym> 3). Most application servers include
(<acronym>JDBC</acronym> 3). Most application servers include
the <acronym>JDBC</acronym> 2.0 Optional Package, but it is
the <acronym>JDBC</acronym> 2.0 Optional Package, but it is
also available separately from the Sun
also available separately from the Sun
<ulink
<ulink
url="http://java.sun.com/products/jdbc/download.html#spec"><acronym>JDBC</acronym> download site</ulink>.
url="http://java.sun.com/products/jdbc/download.html#spec"><acronym>JDBC</acronym> download site</ulink>.
</para>
</para>
</sect2>
<sect2 id="jdbc-ds-intro">
<sect2 id="jdbc-ds-intro">
<title>JDBC Connection Pooling API</title>
<title>Overview</title>
<para>The <acronym>JDBC</acronym> API provides a client
<para>
The <acronym>JDBC</acronym> API provides a client
and a server interface for connection pooling. The client
and a server interface for connection pooling. The client
interface is <literal>javax.sql.DataSource</literal>,
interface is <literal>javax.sql.DataSource</literal>,
which is what application code will typically use to
which is what application code will typically use to
...
@@ -2535,16 +2518,22 @@ public void unlink(int oid) throws SQLException
...
@@ -2535,16 +2518,22 @@ public void unlink(int oid) throws SQLException
is <literal>javax.sql.ConnectionPoolDataSource</literal>,
is <literal>javax.sql.ConnectionPoolDataSource</literal>,
which is how most application servers will interface with
which is how most application servers will interface with
the <productname>PostgreSQL</productname> <acronym>JDBC</acronym>
the <productname>PostgreSQL</productname> <acronym>JDBC</acronym>
driver.</para>
driver.
<para>In an application server environment, the
</para>
<para>
In an application server environment, the
application server configuration will typically refer to
application server configuration will typically refer to
the <productname>PostgreSQL</productname>
the <productname>PostgreSQL</productname>
<literal>ConnectionPoolDataSource</literal> implementation,
<literal>ConnectionPoolDataSource</literal> implementation,
while the application component code will typically acquire a
while the application component code will typically acquire a
<literal>DataSource</literal> implementation provided by
<literal>DataSource</literal> implementation provided by
the application server (not by
the application server (not by
<productname>PostgreSQL</productname>).</para>
<productname>PostgreSQL</productname>).
<para>In an environment without an application server,
</para>
<para>
For an environment without an application server,
<productname>PostgreSQL</productname> provides two implementations
<productname>PostgreSQL</productname> provides two implementations
of <literal>DataSource</literal> which an application can use
of <literal>DataSource</literal> which an application can use
directly. One implementation performs connection pooling,
directly. One implementation performs connection pooling,
...
@@ -2553,19 +2542,23 @@ public void unlink(int oid) throws SQLException
...
@@ -2553,19 +2542,23 @@ public void unlink(int oid) throws SQLException
any pooling. Again, these implementations should not be used
any pooling. Again, these implementations should not be used
in an application server environment unless the application
in an application server environment unless the application
server does not support the
server does not support the
<literal>ConnectionPoolDataSource</literal> interface.</para>
<literal>ConnectionPoolDataSource</literal> interface.
</para>
</sect2>
</sect2>
<sect2 id="jdbc-ds-cpds">
<sect2 id="jdbc-ds-cpds">
<title>Application Servers: ConnectionPoolDataSource</title>
<title>Application Servers: <classname>ConnectionPoolDataSource</classname></title>
<para><productname>PostgreSQL</productname> includes one
implementation of <literal>ConnectionPoolDataSource</literal>
<para>
for <acronym>JDBC</acronym> 2, and one for
<productname>PostgreSQL</productname> includes one implementation
<acronym>JDBC</acronym> 3:</para>
of <classname>ConnectionPoolDataSource</classname> for
<acronym>JDBC</acronym> 2 and one for <acronym>JDBC</acronym> 3,
as shown in <xref linkend="jdbc-ds-cpds-imp-table">.
</para>
<table
>
<table id="jdbc-ds-cpds-imp-table"
>
<title>
ConnectionPoolDataSource
Implementations</title>
<title>
<classname>ConnectionPoolDataSource</classname>
Implementations</title>
<tgroup cols=2>
<tgroup cols=2>
<thead>
<thead>
...
@@ -2587,15 +2580,18 @@ public void unlink(int oid) throws SQLException
...
@@ -2587,15 +2580,18 @@ public void unlink(int oid) throws SQLException
</row>
</row>
</tbody>
</tbody>
</tgroup>
</tgroup>
</table>
</table>
<para>Both implementations use the same configuration scheme.
<para>
<acronym>JDBC</acronym> requires that a
Both implementations use the same configuration scheme.
<literal>ConnectionPoolDataSource</literal> be configured via
<acronym>JDBC</acronym> requires that a
JavaBean properties, so there are get and set methods for each of
<classname>ConnectionPoolDataSource</classname> be configured via
these properties:</para>
JavaBean properties, shown in <xref linkend="jdbc-ds-cpds-props">,
<table>
so there are get and set methods for each of these properties.
<title>ConnectionPoolDataSource Configuration Properties</title>
</para>
<table id="jdbc-ds-cpds-props">
<title><classname>ConnectionPoolDataSource</> Configuration Properties</title>
<tgroup cols=3>
<tgroup cols=3>
<thead>
<thead>
...
@@ -2608,97 +2604,98 @@ public void unlink(int oid) throws SQLException
...
@@ -2608,97 +2604,98 @@ public void unlink(int oid) throws SQLException
<tbody>
<tbody>
<row>
<row>
<entry>
serverName
</entry>
<entry>
<literal>serverName</literal>
</entry>
<entry><
literal>String</literal
></entry>
<entry><
type>String</type
></entry>
<entry><productname>PostgreSQL</productname> database server
<entry><productname>PostgreSQL</productname> database server
hostname</entry>
host
name</entry>
</row>
</row>
<row>
<row>
<entry>
databaseName
</entry>
<entry>
<literal>databaseName</literal>
</entry>
<entry><
literal>String</literal
></entry>
<entry><
type>String</type
></entry>
<entry><productname>PostgreSQL</productname> database name</entry>
<entry><productname>PostgreSQL</productname> database name</entry>
</row>
</row>
<row>
<row>
<entry>portNumber</entry>
<entry><literal>portNumber</literal></entry>
<entry><literal>int</literal></entry>
<entry><type>int</type></entry>
<entry><acronym>TCP/IP</acronym> port which the
<entry>
<productname>PostgreSQL</productname> database server is
TCP port which the <productname>PostgreSQL</productname>
listening on (or 0 to use the default port)</entry>
database server is listening on (or 0 to use the default port)
</entry>
</row>
</row>
<row>
<row>
<entry>
user
</entry>
<entry>
<literal>user</literal>
</entry>
<entry><
literal>String</literal
></entry>
<entry><
type>String</type
></entry>
<entry>User used to make database connections</entry>
<entry>User used to make database connections</entry>
</row>
</row>
<row>
<row>
<entry>
password
</entry>
<entry>
<literal>password</literal>
</entry>
<entry><
literal>String</literal
></entry>
<entry><
type>String</type
></entry>
<entry>Password used to make database connections</entry>
<entry>Password used to make database connections</entry>
</row>
</row>
<row>
<row>
<entry>defaultAutoCommit</entry>
<entry><literal>defaultAutoCommit</literal></entry>
<entry><literal>boolean</literal></entry>
<entry><type>boolean</type></entry>
<entry>Whether connections should have autoCommit
<entry>
enabled or disabled when they are supplied to the
Whether connections should have autocommit enabled or disabled
caller. The default is <literal>false</literal>, to
when they are supplied to the caller. The default is
disable autoCommit.</entry>
<literal>false</literal>, to disable autocommit.
</entry>
</row>
</row>
</tbody>
</tbody>
</tgroup>
</tgroup>
</table>
</table>
<para>Many application servers use a properties-style syntax to
configure these properties, so it would not be unusual to
enter properties as a block of text.</para>
<
example id="jdbc-cpds-config"
>
<
para
>
<title><literal>ConnectionPoolDataSource</literal> Configuration Example</title>
Many application servers use a properties-style syntax to
configure these properties, so it would not be unusual to enter
<para>
properties as a block of text. If the application server provides
If the application server provides a single area to enter all
a single area to enter all the properties, they might be listed
the properties, they might be listed
like this:
like this:
<programlisting>
<programlisting>
serverName=localhost
serverName=localhost
databaseName=test
databaseName=test
user=testuser
user=testuser
password=testpassword
password=testpassword
</programlisting>
</programlisting>
Or, separated by semicolons instead of newlines, like this:
Or, if semicolons are used as separators instead of newlines, it
could look like this:
<programlisting>
<programlisting>
serverName=localhost;databaseName=test;user=testuser;password=testpassword
serverName=localhost;databaseName=test;user=testuser;password=testpassword
</programlisting>
</programlisting>
</para>
</para>
</example>
</sect2>
</sect2>
<sect2 id="jdbc-ds-ds">
<sect2 id="jdbc-ds-ds">
<title>Applications: DataSource</title>
<title>Applications: <classname>DataSource</></title>
<para><productname>PostgreSQL</productname> includes two
<para><productname>PostgreSQL</productname> includes two
implementations of <literal>DataSource</literal>
implementations of <literal>DataSource</literal>
for <acronym>JDBC</acronym> 2, and two for <acronym>JDBC</acronym>
for <acronym>JDBC</acronym> 2 and two for <acronym>JDBC</acronym>
3. The pooling implementations do not actually close connections
3, as shown in <xref linkend="jdbc-ds-ds-imp">.
The pooling implementations do not actually close connections
when the client calls the <literal>close</literal> method, but
when the client calls the <literal>close</literal> method, but
instead return the connections to a pool of available connections
instead return the connections to a pool of available connections
for other clients to use. This avoids any overhead of repeatedly
for other clients to use. This avoids any overhead of repeatedly
opening and closing connections, and allows a large number of
opening and closing connections, and allows a large number of
clients to share a small number of database connections.</para>
clients to share a small number of database connections.</para>
<para>The pooling datasource implementation provided here is not
<para>The pooling data
-
source implementation provided here is not
the most feature-rich in the world. Among other things,
the most feature-rich in the world. Among other things,
connections are never closed until the pool itself is closed;
connections are never closed until the pool itself is closed;
there is no way to shrink the pool. As well, connections
there is no way to shrink the pool. As well, connections
requested for users other than the default configured user are
requested for users other than the default configured user are
not pooled. Many application servers
not pooled. Many application servers
provide more advanced pooling features
,
and use the
provide more advanced pooling features and use the
<literal>ConnectionPoolDataSource</literal> implementation
<literal>ConnectionPoolDataSource</literal> implementation
instead.</para>
instead.</para>
<table>
<title>DataSource Implementations</title>
<table id="jdbc-ds-ds-imp">
<title><classname>DataSource</> Implementations</title>
<tgroup cols=3>
<tgroup cols=3>
<thead>
<thead>
...
@@ -2738,14 +2735,16 @@ serverName=localhost;databaseName=test;user=testuser;password=testpassword
...
@@ -2738,14 +2735,16 @@ serverName=localhost;databaseName=test;user=testuser;password=testpassword
</tgroup>
</tgroup>
</table>
</table>
<para>All the implementations use the same configuration scheme.
<para>
All the implementations use the same configuration scheme.
<acronym>JDBC</acronym> requires that a
<acronym>JDBC</acronym> requires that a
<literal>DataSource</literal> be configured via
<literal>DataSource</literal> be configured via JavaBean
JavaBean properties, so there are get and set methods for each of
properties, shown in <xref linkend="jdbc-ds-ds-props">, so there
these properties.</para>
are get and set methods for each of these properties.
</para>
<table>
<table
id="jdbc-ds-ds-props"
>
<title>
DataSource
Configuration Properties</title>
<title>
<classname>DataSource</>
Configuration Properties</title>
<tgroup cols=3>
<tgroup cols=3>
<thead>
<thead>
...
@@ -2758,35 +2757,35 @@ serverName=localhost;databaseName=test;user=testuser;password=testpassword
...
@@ -2758,35 +2757,35 @@ serverName=localhost;databaseName=test;user=testuser;password=testpassword
<tbody>
<tbody>
<row>
<row>
<entry>
serverName
</entry>
<entry>
<literal>serverName</literal>
</entry>
<entry><
literal>String</literal
></entry>
<entry><
type>String</type
></entry>
<entry><productname>PostgreSQL</productname> database server
<entry><productname>PostgreSQL</productname> database server
hostname</entry>
host
name</entry>
</row>
</row>
<row>
<row>
<entry>
databaseName
</entry>
<entry>
<literal>databaseName</literal>
</entry>
<entry><
literal>String</literal
></entry>
<entry><
type>String</type
></entry>
<entry><productname>PostgreSQL</productname> database name</entry>
<entry><productname>PostgreSQL</productname> database name</entry>
</row>
</row>
<row>
<row>
<entry>
portNumber
</entry>
<entry>
<literal>portNumber</literal>
</entry>
<entry><
literal>int</literal
></entry>
<entry><
type>int</type
></entry>
<entry>
<acronym>TCP/IP</acronym>
port which the
<entry>
TCP
port which the
<productname>PostgreSQL</productname> database server is
<productname>PostgreSQL</productname> database server is
listening on (or 0 to use the default port)</entry>
listening on (or 0 to use the default port)</entry>
</row>
</row>
<row>
<row>
<entry>
user
</entry>
<entry>
<literal>user</literal>
</entry>
<entry><
literal>String</literal
></entry>
<entry><
type>String</type
></entry>
<entry>User used to make database connections</entry>
<entry>User used to make database connections</entry>
</row>
</row>
<row>
<row>
<entry>
password
</entry>
<entry>
<literal>password</literal>
</entry>
<entry><
literal>String</literal
></entry>
<entry><
type>String</type
></entry>
<entry>Password used to make database connections</entry>
<entry>Password used to make database connections</entry>
</row>
</row>
</tbody>
</tbody>
...
@@ -2794,10 +2793,10 @@ serverName=localhost;databaseName=test;user=testuser;password=testpassword
...
@@ -2794,10 +2793,10 @@ serverName=localhost;databaseName=test;user=testuser;password=testpassword
</table>
</table>
<para>The pooling implementations require some additional
<para>The pooling implementations require some additional
configuration properties
:
</para>
configuration properties
, which are shown in <xref linkend="jdbc-ds-ds-xprops">.
</para>
<table
>
<table id="jdbc-ds-ds-xprops"
>
<title>Additional Pooling
DataSource
Configuration Properties</title>
<title>Additional Pooling
<classname>DataSource</>
Configuration Properties</title>
<tgroup cols=3>
<tgroup cols=3>
<thead>
<thead>
...
@@ -2810,22 +2809,22 @@ serverName=localhost;databaseName=test;user=testuser;password=testpassword
...
@@ -2810,22 +2809,22 @@ serverName=localhost;databaseName=test;user=testuser;password=testpassword
<tbody>
<tbody>
<row>
<row>
<entry>
dataSourceName
</entry>
<entry>
<literal>dataSourceName</literal>
</entry>
<entry><
literal>String</literal
></entry>
<entry><
type>String</type
></entry>
<entry>Every pooling <literal>DataSource</literal> must have a
<entry>Every pooling <literal>DataSource</literal> must have a
unique name</entry>
unique name
.
</entry>
</row>
</row>
<row>
<row>
<entry>
initialConnections
</entry>
<entry>
<literal>initialConnections</literal>
</entry>
<entry><
literal>int</literal
></entry>
<entry><
type>int</type
></entry>
<entry>The number of database connections to be created
<entry>The number of database connections to be created
when the pool is initialized.</entry>
when the pool is initialized.</entry>
</row>
</row>
<row>
<row>
<entry>
maxConnections
</entry>
<entry>
<literal>maxConnections</literal>
</entry>
<entry><
literal>int</literal
></entry>
<entry><
type>int</type
></entry>
<entry>The maximum number of open database connections to
<entry>The maximum number of open database connections to
allow. When more connections are requested, the caller
allow. When more connections are requested, the caller
will hang until a connection is returned to the pool.</entry>
will hang until a connection is returned to the pool.</entry>
...
@@ -2834,14 +2833,14 @@ serverName=localhost;databaseName=test;user=testuser;password=testpassword
...
@@ -2834,14 +2833,14 @@ serverName=localhost;databaseName=test;user=testuser;password=testpassword
</tgroup>
</tgroup>
</table>
</table>
<para>
Here'
s an example of typical application code using a
<para>
<xref linkend="jdbc-ds-example"> show
s an example of typical application code using a
pooling <literal>DataSource</literal>
:
</para>
pooling <literal>DataSource</literal>
.
</para>
<example id="jdbc-ds-
cod
e">
<example id="jdbc-ds-
exampl
e">
<title><literal>DataSource</literal> Code Example</title>
<title><literal>DataSource</literal> Code Example</title>
<para>
<para>
Code to initialize a pooling
DataSource
might look like this:
Code to initialize a pooling
<classname>DataSource</classname>
might look like this:
<programlisting>
<programlisting>
Jdbc3PoolingDataSource source = new Jdbc3PoolingDataSource();
Jdbc3PoolingDataSource source = new Jdbc3PoolingDataSource();
source.setDataSourceName("A Data Source");
source.setDataSourceName("A Data Source");
...
@@ -2853,18 +2852,18 @@ source.setMaxConnections(10);
...
@@ -2853,18 +2852,18 @@ source.setMaxConnections(10);
</programlisting>
</programlisting>
Then code to use a connection from the pool might look
Then code to use a connection from the pool might look
like this. Note that it is critical that the connections
like this. Note that it is critical that the connections
are
closed, or else the pool will "leak" connections,
and
are
eventually closed. Else the pool will <quote>leak</> connections
and
eventually lock all the clients out.
will
eventually lock all the clients out.
<programlisting>
<programlisting>
Connection con = null;
Connection con = null;
try {
try {
con = source.getConnection();
con = source.getConnection();
// use connection
// use connection
} catch(SQLException e) {
} catch
(SQLException e) {
// log error
// log error
} finally {
} finally {
if(con != null) {
if
(con != null) {
try {
con.close();}catch
(SQLException e) {}
try {
con.close(); } catch
(SQLException e) {}
}
}
}
}
</programlisting>
</programlisting>
...
@@ -2873,34 +2872,44 @@ try {
...
@@ -2873,34 +2872,44 @@ try {
</sect2>
</sect2>
<sect2 id="jdbc-jndi">
<sect2 id="jdbc-jndi">
<title>DataSources and <acronym>JNDI</acronym></title>
<title>Data Sources and <acronym>JNDI</acronym></title>
<para>All the <literal>ConnectionPoolDataSource</literal> and
<para>
All the <literal>ConnectionPoolDataSource</literal> and
<literal>DataSource</literal> implementations can be stored
<literal>DataSource</literal> implementations can be stored
in <acronym>JNDI</acronym>. In the case of the non
-
pooling
in <acronym>JNDI</acronym>. In the case of the nonpooling
implementations, a new instance will be created every time the
implementations, a new instance will be created every time the
object is retrieved from <acronym>JNDI</acronym>, with the
object is retrieved from <acronym>JNDI</acronym>, with the
same settings as the instance
which
was stored. For the
same settings as the instance
that
was stored. For the
pooling implementations, the same instance will be retrieved
pooling implementations, the same instance will be retrieved
as long as it is available (e.g. not a different
as long as it is available (e.g.
,
not a different
<acronym>JVM</acronym> retrieving the pool from
<acronym>JVM</acronym> retrieving the pool from
<acronym>JNDI</acronym>), or a new instance with the same
<acronym>JNDI</acronym>), or a new instance with the same
settings created otherwise.</para>
settings created otherwise.
<para>In the application server environment, typically the
</para>
<para>
In the application server environment, typically the
application server's <literal>DataSource</literal> instance
application server's <literal>DataSource</literal> instance
will be stored in <acronym>JNDI</acronym>, instead of the
will be stored in <acronym>JNDI</acronym>, instead of the
<productname>PostgreSQL</productname>
<productname>PostgreSQL</productname>
<literal>ConnectionPoolDataSource</literal> implementation.
<literal>ConnectionPoolDataSource</literal> implementation.
</para>
</para>
<para>In an application environment, the application may store
<para>
In an application environment, the application may store
the <literal>DataSource</literal> in <acronym>JNDI</acronym>
the <literal>DataSource</literal> in <acronym>JNDI</acronym>
so that it doesn't have to make a reference to the
so that it doesn't have to make a reference to the
<literal>DataSource</literal> available to all application
<literal>DataSource</literal> available to all application
components that may need to use it:</para>
components that may need to use it. An example of this is
shown in <xref linkend="jdbc-ds-jndi">.
</para>
<example id="jdbc-ds-jndi">
<example id="jdbc-ds-jndi">
<title><
literal>DataSource</literal
> <acronym>JNDI</acronym> Code Example</title>
<title><
classname>DataSource</classname
> <acronym>JNDI</acronym> Code Example</title>
<para>
<para>
Application code to initialize a pooling
DataSource
and add
Application code to initialize a pooling
<classname>DataSource</classname>
and add
it to <acronym>JNDI</acronym> might look like this:
it to <acronym>JNDI</acronym> might look like this:
<programlisting>
<programlisting>
Jdbc3PoolingDataSource source = new Jdbc3PoolingDataSource();
Jdbc3PoolingDataSource source = new Jdbc3PoolingDataSource();
...
@@ -2920,13 +2929,13 @@ try {
...
@@ -2920,13 +2929,13 @@ try {
DataSource source = (DataSource)new InitialContext().lookup("DataSource");
DataSource source = (DataSource)new InitialContext().lookup("DataSource");
con = source.getConnection();
con = source.getConnection();
// use connection
// use connection
} catch(SQLException e) {
} catch
(SQLException e) {
// log error
// log error
} catch(NamingException e) {
} catch
(NamingException e) {
// DataSource wasn't found in JNDI
// DataSource wasn't found in JNDI
} finally {
} finally {
if(con != null) {
if
(con != null) {
try {
con.close();}catch
(SQLException e) {}
try {
con.close(); } catch
(SQLException e) {}
}
}
}
}
</programlisting>
</programlisting>
...
@@ -2934,30 +2943,25 @@ try {
...
@@ -2934,30 +2943,25 @@ try {
</example>
</example>
</sect2>
</sect2>
<sect2 id="jdbc-app-servers">
<title>Specific Application Server Configurations</title>
<para>Configuration examples for specific application servers
will be included here.</para>
</sect2>
</sect1>
</sect1>
<sect1 id="jdbc-reading">
<sect1 id="jdbc-reading">
<title>Further Reading</title>
<title>Further Reading</title>
<para>
<para>
If you have not yet read it,
I'd advise
you read the
If you have not yet read it,
you are advised
you read the
<acronym>JDBC</acronym> <acronym>API</acronym> Documentation
<acronym>JDBC</acronym> <acronym>API</acronym> Documentation
(supplied with Sun's <acronym>JDK</acronym>)
,
and the
(supplied with Sun's <acronym>JDK</acronym>) and the
<acronym>JDBC</acronym> Specification. Both are available from
<acronym>JDBC</acronym> Specification. Both are available from
<ulink
<ulink
url="http://java.sun.com/products/jdbc/index.html">
http://java.sun.com/products/jdbc/index.html
</ulink>.
url="http://java.sun.com/products/jdbc/index.html"></ulink>.
</para>
</para>
<para>
<para>
<ulink
<ulink
url="http://jdbc.postgresql.org">
http://jdbc.postgresql.org
</ulink>
url="http://jdbc.postgresql.org"></ulink>
contains updated information not included in this
document,
and
contains updated information not included in this
chapter
and
also
include
s precompiled drivers.
also
offer
s precompiled drivers.
</para>
</para>
</sect1>
</sect1>
</chapter>
</chapter>
...
...
doc/src/sgml/plperl.sgml
View file @
a8cb3368
<!--
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/plperl.sgml,v 2.1
8 2002/09/21 18:32:53
petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/plperl.sgml,v 2.1
9 2003/04/07 01:29:25
petere Exp $
-->
-->
<chapter id="plperl">
<chapter id="plperl">
...
@@ -34,8 +34,8 @@ $Header: /cvsroot/pgsql/doc/src/sgml/plperl.sgml,v 2.18 2002/09/21 18:32:53 pete
...
@@ -34,8 +34,8 @@ $Header: /cvsroot/pgsql/doc/src/sgml/plperl.sgml,v 2.18 2002/09/21 18:32:53 pete
<note>
<note>
<para>
<para>
Users of source packages must specially enable the build of
Users of source packages must specially enable the build of
PL/Perl during the installation process
(r
efer to the installation
PL/Perl during the installation process
. (R
efer to the installation
instructions for more information
).
Users of binary packages
instructions for more information
.)
Users of binary packages
might find PL/Perl in a separate subpackage.
might find PL/Perl in a separate subpackage.
</para>
</para>
</note>
</note>
...
@@ -57,8 +57,12 @@ CREATE FUNCTION <replaceable>funcname</replaceable> (<replaceable>argument-types
...
@@ -57,8 +57,12 @@ CREATE FUNCTION <replaceable>funcname</replaceable> (<replaceable>argument-types
Arguments and results are handled as in any other Perl subroutine:
Arguments and results are handled as in any other Perl subroutine:
Arguments are passed in <varname>@_</varname>, and a result value
Arguments are passed in <varname>@_</varname>, and a result value
is returned with <literal>return</> or as the last expression
is returned with <literal>return</> or as the last expression
evaluated in the function. For example, a function returning the
evaluated in the function.
greater of two integer values could be defined as:
</para>
<para>
For example, a function returning the greater of two integer values
could be defined as:
<programlisting>
<programlisting>
CREATE FUNCTION perl_max (integer, integer) RETURNS integer AS '
CREATE FUNCTION perl_max (integer, integer) RETURNS integer AS '
...
@@ -145,7 +149,7 @@ SELECT name, empcomp(employee) FROM employee;
...
@@ -145,7 +149,7 @@ SELECT name, empcomp(employee) FROM employee;
<title>Data Values in PL/Perl</title>
<title>Data Values in PL/Perl</title>
<para>
<para>
The argument values supplied to a PL/Perl function's
script
are
The argument values supplied to a PL/Perl function's
code
are
simply the input arguments converted to text form (just as if they
simply the input arguments converted to text form (just as if they
had been displayed by a <literal>SELECT</literal> statement).
had been displayed by a <literal>SELECT</literal> statement).
Conversely, the <literal>return</> command will accept any string
Conversely, the <literal>return</> command will accept any string
...
@@ -206,8 +210,8 @@ SELECT name, empcomp(employee) FROM employee;
...
@@ -206,8 +210,8 @@ SELECT name, empcomp(employee) FROM employee;
environment. This includes file handle operations,
environment. This includes file handle operations,
<literal>require</literal>, and <literal>use</literal> (for
<literal>require</literal>, and <literal>use</literal> (for
external modules). There is no way to access internals of the
external modules). There is no way to access internals of the
database
backend
process or to gain OS-level access with the
database
server
process or to gain OS-level access with the
permissions of the
<productname>PostgreSQL</productname> user ID
,
permissions of the
server process
,
as a C function can do. Thus, any unprivileged database user may
as a C function can do. Thus, any unprivileged database user may
be permitted to use this language.
be permitted to use this language.
</para>
</para>
...
@@ -227,7 +231,7 @@ CREATE FUNCTION badfunc() RETURNS integer AS '
...
@@ -227,7 +231,7 @@ CREATE FUNCTION badfunc() RETURNS integer AS '
<para>
<para>
Sometimes it is desirable to write Perl functions that are not
Sometimes it is desirable to write Perl functions that are not
restricted
--- f
or example, one might want a Perl function that
restricted
. F
or example, one might want a Perl function that
sends mail. To handle these cases, PL/Perl can also be installed
sends mail. To handle these cases, PL/Perl can also be installed
as an <quote>untrusted</> language (usually called
as an <quote>untrusted</> language (usually called
<application>PL/PerlU</application>). In this case the full Perl language is
<application>PL/PerlU</application>). In this case the full Perl language is
...
@@ -255,7 +259,7 @@ CREATE FUNCTION badfunc() RETURNS integer AS '
...
@@ -255,7 +259,7 @@ CREATE FUNCTION badfunc() RETURNS integer AS '
<para>
<para>
The following features are currently missing from PL/Perl, but they
The following features are currently missing from PL/Perl, but they
would make welcome contributions
:
would make welcome contributions
.
<itemizedlist>
<itemizedlist>
<listitem>
<listitem>
...
...
doc/src/sgml/plpgsql.sgml
View file @
a8cb3368
This source diff could not be displayed because it is too large. You can
view the blob
instead.
doc/src/sgml/plpython.sgml
View file @
a8cb3368
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/plpython.sgml,v 1.1
5 2002/10/21 20:34:09 momjian
Exp $ -->
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/plpython.sgml,v 1.1
6 2003/04/07 01:29:25 petere
Exp $ -->
<chapter id="plpython">
<chapter id="plpython">
<title>PL/Python - Python Procedural Language</title>
<title>PL/Python - Python Procedural Language</title>
...
@@ -17,11 +17,18 @@
...
@@ -17,11 +17,18 @@
<literal>createlang plpython <replaceable>dbname</></literal>.
<literal>createlang plpython <replaceable>dbname</></literal>.
</para>
</para>
<tip>
<para>
If a language is installed into <literal>template1</>, all subsequently
created databases will have the language installed automatically.
</para>
</tip>
<note>
<note>
<para>
<para>
Users of source packages must specially enable the build of
Users of source packages must specially enable the build of
PL/Python during the installation process
(r
efer to the
PL/Python during the installation process
. (R
efer to the
installation instructions for more information
).
Users of binary
installation instructions for more information
.)
Users of binary
packages might find PL/Python in a separate subpackage.
packages might find PL/Python in a separate subpackage.
</para>
</para>
</note>
</note>
...
@@ -30,11 +37,11 @@
...
@@ -30,11 +37,11 @@
<title>PL/Python Functions</title>
<title>PL/Python Functions</title>
<para>
<para>
The Python code you write gets transformed into a function. E.g.,
The Python code you write gets transformed into a
Python
function. E.g.,
<programlisting>
<programlisting>
CREATE FUNCTION myfunc(text) RETURNS text
CREATE FUNCTION myfunc(text) RETURNS text
AS 'return args[0]'
AS 'return args[0]'
LANGUAGE
'plpython'
;
LANGUAGE
plpython
;
</programlisting>
</programlisting>
gets transformed into
gets transformed into
...
@@ -49,7 +56,7 @@ def __plpython_procedure_myfunc_23456():
...
@@ -49,7 +56,7 @@ def __plpython_procedure_myfunc_23456():
<para>
<para>
If you do not provide a return value, Python returns the default
If you do not provide a return value, Python returns the default
<symbol>None</symbol>
which may or may not be what you want.
The
<symbol>None</symbol>
.
The
language module translates Python's <symbol>None</symbol> into the
language module translates Python's <symbol>None</symbol> into the
SQL null value.
SQL null value.
</para>
</para>
...
@@ -60,8 +67,8 @@ def __plpython_procedure_myfunc_23456():
...
@@ -60,8 +67,8 @@ def __plpython_procedure_myfunc_23456():
<function>myfunc</function> example, <varname>args[0]</> contains
<function>myfunc</function> example, <varname>args[0]</> contains
whatever was passed in as the text argument. For
whatever was passed in as the text argument. For
<literal>myfunc2(text, integer)</literal>, <varname>args[0]</>
<literal>myfunc2(text, integer)</literal>, <varname>args[0]</>
would contain the <type>text</type>
variable
and
would contain the <type>text</type>
argument
and
<varname>args[1]</varname> the <type>integer</type>
variable
.
<varname>args[1]</varname> the <type>integer</type>
argument
.
</para>
</para>
<para>
<para>
...
@@ -95,14 +102,14 @@ def __plpython_procedure_myfunc_23456():
...
@@ -95,14 +102,14 @@ def __plpython_procedure_myfunc_23456():
<literal>TD["level"]</> contains one of <literal>ROW</>,
<literal>TD["level"]</> contains one of <literal>ROW</>,
<literal>STATEMENT</>, and <literal>UNKNOWN</>.
<literal>STATEMENT</>, and <literal>UNKNOWN</>.
<literal>TD["name"]</> contains the trigger name, and
<literal>TD["name"]</> contains the trigger name, and
<literal>TD["relid"]</> contains the
relation
ID of the table on
<literal>TD["relid"]</> contains the
O
ID of the table on
which the trigger occurred. If the trigger was called with
which the trigger occurred. If the trigger was called with
arguments they are available in <literal>TD["args"][0]</> to
arguments they are available in <literal>TD["args"][0]</> to
<literal>TD["args"][(n-1)]</>.
<literal>TD["args"][(n-1)]</>.
</para>
</para>
<para>
<para>
If
the
<literal>TD["when"]</literal> is <literal>BEFORE</>, you may
If <literal>TD["when"]</literal> is <literal>BEFORE</>, you may
return <literal>None</literal> or <literal>"OK"</literal> from the
return <literal>None</literal> or <literal>"OK"</literal> from the
Python function to indicate the row is unmodified,
Python function to indicate the row is unmodified,
<literal>"SKIP"</> to abort the event, or <literal>"MODIFY"</> to
<literal>"SKIP"</> to abort the event, or <literal>"MODIFY"</> to
...
@@ -147,10 +154,10 @@ def __plpython_procedure_myfunc_23456():
...
@@ -147,10 +154,10 @@ def __plpython_procedure_myfunc_23456():
optional limit argument causes that query to be run and the result
optional limit argument causes that query to be run and the result
to be returned in a result object. The result object emulates a
to be returned in a result object. The result object emulates a
list or dictionary object. The result object can be accessed by
list or dictionary object. The result object can be accessed by
row number and
field
name. It has these additional methods:
row number and
column
name. It has these additional methods:
<function>nrows
()
</function> which returns the number of rows
<function>nrows</function> which returns the number of rows
returned by the query, and <function>status</function> which is the
returned by the query, and <function>status</function> which is the
<function>SPI_exec
</function> return variabl
e. The result object
<function>SPI_exec
()</function> return valu
e. The result object
can be modified.
can be modified.
</para>
</para>
...
@@ -161,27 +168,27 @@ rv = plpy.execute("SELECT * FROM my_table", 5)
...
@@ -161,27 +168,27 @@ rv = plpy.execute("SELECT * FROM my_table", 5)
</programlisting>
</programlisting>
returns up to 5 rows from <literal>my_table</literal>. If
returns up to 5 rows from <literal>my_table</literal>. If
<literal>my_table</literal> has a column
<literal>my_table</literal> has a column
<literal>my_
field
</literal>, it would be accessed as
<literal>my_
column
</literal>, it would be accessed as
<programlisting>
<programlisting>
foo = rv[i]["my_
field
"]
foo = rv[i]["my_
column
"]
</programlisting>
</programlisting>
</para>
</para>
<para>
<para>
The second function <function>plpy.prepare</function> is called
The second function, <function>plpy.prepare</function>, prepares the
with a query string and a list of argument types if you have bind
execution plan for a query. It is called with a query string and a
variables in the query. For example:
list of parameter types, if you have parameter references in the
query. For example:
<programlisting>
<programlisting>
plan = plpy.prepare("SELECT last_name FROM my_users WHERE first_name = $1", [ "text" ])
plan = plpy.prepare("SELECT last_name FROM my_users WHERE first_name = $1", [ "text" ])
</programlisting>
</programlisting>
<literal>text</literal> is the type of the variable you will be
<literal>text</literal> is the type of the variable you will be
passing
as
<literal>$1</literal>. After preparing a statement, you
passing
for
<literal>$1</literal>. After preparing a statement, you
use the function <function>plpy.execute</function> to run it:
use the function <function>plpy.execute</function> to run it:
<programlisting>
<programlisting>
rv = plpy.execute(plan, [ "name" ], 5)
rv = plpy.execute(plan, [ "name" ], 5)
</programlisting>
</programlisting>
The limit argument is optional in the call to
The third argument is the limit and is optional.
<function>plpy.execute</function>.
</para>
</para>
<para>
<para>
...
@@ -190,7 +197,7 @@ rv = plpy.execute(plan, [ "name" ], 5)
...
@@ -190,7 +197,7 @@ rv = plpy.execute(plan, [ "name" ], 5)
in the immediate termination of that function by the server; it is
in the immediate termination of that function by the server; it is
not possible to trap error conditions using Python <literal>try
not possible to trap error conditions using Python <literal>try
... catch</literal> constructs. For example, a syntax error in an
... catch</literal> constructs. For example, a syntax error in an
SQL statement passed to the <literal>plpy.execute
()
</literal> call
SQL statement passed to the <literal>plpy.execute</literal> call
will terminate the function. This behavior may be changed in a
will terminate the function. This behavior may be changed in a
future release.
future release.
</para>
</para>
...
@@ -199,22 +206,19 @@ rv = plpy.execute(plan, [ "name" ], 5)
...
@@ -199,22 +206,19 @@ rv = plpy.execute(plan, [ "name" ], 5)
When you prepare a plan using the PL/Python module it is
When you prepare a plan using the PL/Python module it is
automatically saved. Read the SPI documentation (<xref
automatically saved. Read the SPI documentation (<xref
linkend="spi">) for a description of what this means.
linkend="spi">) for a description of what this means.
</para>
<para>
In order to make effective use of this across function calls
In order to make effective use of this across function calls
one needs to use one of the persistent storage dictionaries
one needs to use one of the persistent storage dictionaries
<literal>SD</literal> or <literal>GD</literal>
,
see
<literal>SD</literal> or <literal>GD</literal>
(
see
<xref linkend="plpython-funcs">. For example:
<xref linkend="plpython-funcs">
)
. For example:
<programlisting>
<programlisting>
CREATE FUNCTION usesavedplan
( ) RETURNS TRIGGER
AS '
CREATE FUNCTION usesavedplan
() RETURNS trigger
AS '
if SD.has_key("plan"):
if SD.has_key("plan"):
plan = SD["plan"]
plan = SD["plan"]
else:
else:
plan = plpy.prepare("SELECT 1")
plan = plpy.prepare("SELECT 1")
SD["plan"] = plan
SD["plan"] = plan
# rest of function
# rest of function
' LANGUAGE
'plpython'
;
' LANGUAGE
plpython
;
</programlisting>
</programlisting>
</para>
</para>
</sect1>
</sect1>
...
...
doc/src/sgml/pltcl.sgml
View file @
a8cb3368
<!--
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.2
2 2002/09/21 18:32:53
petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.2
3 2003/04/07 01:29:25
petere Exp $
-->
-->
<chapter id="pltcl">
<chapter id="pltcl">
...
@@ -20,10 +20,6 @@ $Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.22 2002/09/21 18:32:53 peter
...
@@ -20,10 +20,6 @@ $Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.22 2002/09/21 18:32:53 peter
trigger procedures.
trigger procedures.
</para>
</para>
<para>
This package was originally written by Jan Wieck.
</para>
<!-- **** PL/Tcl overview **** -->
<!-- **** PL/Tcl overview **** -->
<sect1 id="pltcl-overview">
<sect1 id="pltcl-overview">
...
@@ -38,19 +34,19 @@ $Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.22 2002/09/21 18:32:53 peter
...
@@ -38,19 +34,19 @@ $Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.22 2002/09/21 18:32:53 peter
Tcl interpreter. In addition to the limited command set of safe Tcl, only
Tcl interpreter. In addition to the limited command set of safe Tcl, only
a few commands are available to access the database via SPI and to raise
a few commands are available to access the database via SPI and to raise
messages via <function>elog()</>. There is no way to access internals of the
messages via <function>elog()</>. There is no way to access internals of the
database
backend
or to gain OS-level access under the permissions of the
database
server
or to gain OS-level access under the permissions of the
<productname>PostgreSQL</productname>
user ID
, as a C function can do.
<productname>PostgreSQL</productname>
server process
, as a C function can do.
Thus, any unprivileged database user may be
Thus, any unprivileged database user may be
permitted to use this language.
permitted to use this language.
</para>
</para>
<para>
<para>
The other, implementation restriction is that Tcl
procedure
s cannot
The other, implementation restriction is that Tcl
function
s cannot
be used to create input/output functions for new data types.
be used to create input/output functions for new data types.
</para>
</para>
<para>
<para>
Sometimes it is desirable to write Tcl functions that are not restricted
Sometimes it is desirable to write Tcl functions that are not restricted
to safe Tcl
--- f
or example, one might want a Tcl function that sends
to safe Tcl
. F
or example, one might want a Tcl function that sends
mail. To handle these cases, there is a variant of <application>PL/Tcl</> called <literal>PL/TclU</>
e
mail. To handle these cases, there is a variant of <application>PL/Tcl</> called <literal>PL/TclU</>
(for untrusted Tcl). This is the exact same language except that a full
(for untrusted Tcl). This is the exact same language except that a full
Tcl interpreter is used. <emphasis>If <application>PL/TclU</> is used, it must be
Tcl interpreter is used. <emphasis>If <application>PL/TclU</> is used, it must be
installed as an untrusted procedural language</emphasis> so that only
installed as an untrusted procedural language</emphasis> so that only
...
@@ -66,7 +62,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.22 2002/09/21 18:32:53 peter
...
@@ -66,7 +62,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.22 2002/09/21 18:32:53 peter
library directory if Tcl/Tk support is specified
library directory if Tcl/Tk support is specified
in the configuration step of the installation procedure. To install
in the configuration step of the installation procedure. To install
<application>PL/Tcl</> and/or <application>PL/TclU</> in a particular database, use the
<application>PL/Tcl</> and/or <application>PL/TclU</> in a particular database, use the
<
filename>createlang</filename> script
, for example
<
command>createlang</command> program
, for example
<literal>createlang pltcl <replaceable>dbname</></literal> or
<literal>createlang pltcl <replaceable>dbname</></literal> or
<literal>createlang pltclu <replaceable>dbname</></literal>.
<literal>createlang pltclu <replaceable>dbname</></literal>.
</para>
</para>
...
@@ -74,58 +70,59 @@ $Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.22 2002/09/21 18:32:53 peter
...
@@ -74,58 +70,59 @@ $Header: /cvsroot/pgsql/doc/src/sgml/pltcl.sgml,v 2.22 2002/09/21 18:32:53 peter
<!-- **** PL/Tcl description **** -->
<!-- **** PL/Tcl description **** -->
<sect1 id="pltcl-description">
<sect1 id="pltcl-functions">
<title>Description</title>
<sect2>
<title>PL/Tcl Functions and Arguments</title>
<title>PL/Tcl Functions and Arguments</title>
<para>
<para>
To create a function in the <application>PL/Tcl</> language, use the standard syntax
To create a function in the <application>PL/Tcl</> language, use the standard syntax
:
<programlisting>
<programlisting>
CREATE FUNCTION <replaceable>funcname</replaceable> (<replaceable>argument-types</replaceable>) RETURNS <replaceable>return-type</replaceable> AS '
CREATE FUNCTION <replaceable>funcname</replaceable> (<replaceable>argument-types</replaceable>) RETURNS <replaceable>return-type</replaceable> AS '
# PL/Tcl function body
# PL/Tcl function body
' LANGUAGE
'pltcl'
;
' LANGUAGE
pltcl
;
</programlisting>
</programlisting>
<application>PL/TclU</> is the same, except that the language
should
be specified as
<application>PL/TclU</> is the same, except that the language
has to
be specified as
<literal>pltclu</>.
<literal>pltclu</>.
</para>
</para>
<para>
<para>
The body of the function is simply a piece of Tcl script.
The body of the function is simply a piece of Tcl script.
When the function is called, the argument values are passed as
When the function is called, the argument values are passed as
variables <literal>$1</literal> ... <literal>$
n
</literal> to the
variables <literal>$1</literal> ... <literal>$
<replaceable>n</replaceable>
</literal> to the
Tcl script. The result is returned
Tcl script. The result is returned
from the Tcl code in the usual way, with a <literal>return</literal>
from the Tcl code in the usual way, with a <literal>return</literal>
statement. For example, a function
statement.
</para>
<para>
For example, a function
returning the greater of two integer values could be defined as:
returning the greater of two integer values could be defined as:
<programlisting>
<programlisting>
CREATE FUNCTION tcl_max
(integer, integer) RETURNS integer AS '
CREATE FUNCTION tcl_max(integer, integer) RETURNS integer AS '
if {$1 > $2} {return $1}
if {$1 > $2} {return $1}
return $2
return $2
' LANGUAGE
'pltcl' WITH (isStrict)
;
' LANGUAGE
pltcl STRICT
;
</programlisting>
</programlisting>
Note the clause <literal>
WITH (isStrict)
</>, which saves us from
Note the clause <literal>
STRICT
</>, which saves us from
having to think about
NULL input values: if a NULL
is passed, the
having to think about
null input values: if a null value
is passed, the
function will not be called at all, but will just return a
NULL
function will not be called at all, but will just return a
null
result automatically.
result automatically.
</para>
</para>
<para>
<para>
In a non
-
strict function,
In a nonstrict function,
if the actual value of an argument is
NULL
, the corresponding
if the actual value of an argument is
null
, the corresponding
<literal>$
n
</literal> variable will be set to an empty string.
<literal>$
<replaceable>n</replaceable>
</literal> variable will be set to an empty string.
To detect whether a particular argument is
NULL
, use the function
To detect whether a particular argument is
null
, use the function
<literal>argisnull</>. For example, suppose that we wanted <function>tcl_max</function>
<literal>argisnull</>. For example, suppose that we wanted <function>tcl_max</function>
with one null and one non
-null argument to return the non-
null
with one null and one non
null argument to return the non
null
argument, rather than
NULL
:
argument, rather than
null
:
<programlisting>
<programlisting>
CREATE FUNCTION tcl_max
(integer, integer) RETURNS integer AS '
CREATE FUNCTION tcl_max(integer, integer) RETURNS integer AS '
if {[argisnull 1]} {
if {[argisnull 1]} {
if {[argisnull 2]} { return_null }
if {[argisnull 2]} { return_null }
return $2
return $2
...
@@ -133,8 +130,8 @@ CREATE FUNCTION tcl_max (integer, integer) RETURNS integer AS '
...
@@ -133,8 +130,8 @@ CREATE FUNCTION tcl_max (integer, integer) RETURNS integer AS '
if {[argisnull 2]} { return $1 }
if {[argisnull 2]} { return $1 }
if {$1 > $2} {return $1}
if {$1 > $2} {return $1}
return $2
return $2
' LANGUAGE
'pltcl'
;
' LANGUAGE
pltcl
;
</programlisting>
</programlisting>
</para>
</para>
<para>
<para>
...
@@ -145,15 +142,19 @@ CREATE FUNCTION tcl_max (integer, integer) RETURNS integer AS '
...
@@ -145,15 +142,19 @@ CREATE FUNCTION tcl_max (integer, integer) RETURNS integer AS '
</para>
</para>
<para>
<para>
Composite-type arguments are passed to the procedure as Tcl arrays.
Composite-type arguments are passed to the function as Tcl
The element names of the array are the attribute names of the composite
arrays. The element names of the array are the attribute names
type. If an attribute in the passed row
of the composite type. If an attribute in the passed row has the
has the NULL value, it will not appear in the array! Here is
null value, it will not appear in the array. Here is an example:
an example that defines the overpaid_2 function (as found in the
older <productname>PostgreSQL</productname> documentation) in PL/Tcl:
<programlisting>
CREATE TABLE employee (
<programlisting>
name text,
CREATE FUNCTION overpaid_2 (EMP) RETURNS bool AS '
salary integer,
age integer
);
CREATE FUNCTION overpaid(employee) RETURNS boolean AS '
if {200000.0 < $1(salary)} {
if {200000.0 < $1(salary)} {
return "t"
return "t"
}
}
...
@@ -161,110 +162,109 @@ CREATE FUNCTION overpaid_2 (EMP) RETURNS bool AS '
...
@@ -161,110 +162,109 @@ CREATE FUNCTION overpaid_2 (EMP) RETURNS bool AS '
return "t"
return "t"
}
}
return "f"
return "f"
' LANGUAGE
'pltcl'
;
' LANGUAGE
pltcl
;
</programlisting>
</programlisting>
</para>
</para>
<para>
<para>
There is
not currently any
support for returning a composite-type
There is
currently no
support for returning a composite-type
result value.
result value.
</para>
</para>
</sect
2
>
</sect
1
>
<sect
2
>
<sect
1 id="pltcl-data"
>
<title>Data Values in PL/Tcl</title>
<title>Data Values in PL/Tcl</title>
<para>
<para>
The argument values supplied to a PL/Tcl function's
script
are simply
The argument values supplied to a PL/Tcl function's
code
are simply
the input arguments converted to text form (just as if they had been
the input arguments converted to text form (just as if they had been
displayed by a
SELECT
statement). Conversely, the <literal>return</>
displayed by a
<command>SELECT</>
statement). Conversely, the <literal>return</>
command will accept any string that is acceptable input format for
command will accept any string that is acceptable input format for
the function's declared return type. So, the PL/Tcl programmer can
the function's declared return type. So, the PL/Tcl programmer can
manipulate data values as if they were just text.
manipulate data values as if they were just text.
</para>
</para>
</sect
2
>
</sect
1
>
<sect
2
>
<sect
1 id="pltcl-global"
>
<title>Global Data in PL/Tcl</title>
<title>Global Data in PL/Tcl</title>
<para>
<para>
Sometimes it
Sometimes it
is useful to have some global
status
data that is held between two
is useful to have some global data that is held between two
calls to a
procedure or is shared between different procedure
s.
calls to a
function or is shared between different function
s.
This is easily done since
This is easily done since
all PL/Tcl
procedures executed in one backend
share the same
all PL/Tcl
functions executed in one session
share the same
safe Tcl interpreter. So, any global Tcl variable is accessible to
safe Tcl interpreter. So, any global Tcl variable is accessible to
all PL/Tcl
procedure calls,
and will persist for the duration of the
all PL/Tcl
function calls
and will persist for the duration of the
SQL
client connect
ion. (Note that <application>PL/TclU</> functions likewise share
SQL
sess
ion. (Note that <application>PL/TclU</> functions likewise share
global data, but they are in a different Tcl interpreter and cannot
global data, but they are in a different Tcl interpreter and cannot
communicate with PL/Tcl functions.)
communicate with PL/Tcl functions.)
</para>
</para>
<para>
<para>
To help protect PL/Tcl
procedure
s from unintentionally interfering
To help protect PL/Tcl
function
s from unintentionally interfering
with each other, a global
with each other, a global
array is made available to each
procedure
via the <function>upvar</>
array is made available to each
function
via the <function>upvar</>
command. The global name of this variable is the
procedure
's internal
command. The global name of this variable is the
function
's internal
name and the local name is <literal>GD</>. It is recommended that
name
,
and the local name is <literal>GD</>. It is recommended that
<literal>GD</> be used
<literal>GD</> be used
for private
status data of a procedure
. Use regular Tcl global variables
for private
data of a function
. Use regular Tcl global variables
only for values that you specifically intend to be shared among multiple
only for values that you specifically intend to be shared among multiple
procedure
s.
function
s.
</para>
</para>
<para>
<para>
An example of using <literal>GD</> appears in the
An example of using <literal>GD</> appears in the
<function>spi_execp</function> example below.
<function>spi_execp</function> example below.
</para>
</para>
</sect
2
>
</sect
1
>
<sect
2
>
<sect
1 id="pltcl-dbaccess"
>
<title>Database Access from PL/Tcl</title>
<title>Database Access from PL/Tcl</title>
<para>
<para>
The following commands are available to access the database from
The following commands are available to access the database from
the body of a PL/Tcl procedure:
the body of a PL/Tcl function:
</para>
<variablelist>
<variablelist>
<varlistentry>
<varlistentry>
<term><function>spi_exec</function> <literal>?-count <replaceable>n</replaceable>? ?-array <replaceable>name</replaceable>? <replaceable>
query
</replaceable> ?<replaceable>loop-body</replaceable>?</literal></term>
<term><function>spi_exec</function> <literal>?-count <replaceable>n</replaceable>? ?-array <replaceable>name</replaceable>? <replaceable>
command
</replaceable> ?<replaceable>loop-body</replaceable>?</literal></term>
<listitem>
<listitem>
<para>
<para>
Execute
an SQL query given as a string. An error in the query
Execute
s an SQL command given as a string. An error in the command
causes an error to be raised. Otherwise, the
command's return value
causes an error to be raised. Otherwise, the
return value of <function>spi_exec</function>
is the number of rows processed (selected, inserted, updated, or
is the number of rows processed (selected, inserted, updated, or
deleted) by the
query, or zero if the query
is a utility
deleted) by the
command, or zero if the command
is a utility
statement. In addition, if the
query is a SELECT
statement, the
statement. In addition, if the
command is a <command>SELECT</>
statement, the
values of the selected columns are placed in Tcl variables as
values of the selected columns are placed in Tcl variables as
described below.
described below.
</para>
</para>
<para>
<para>
The optional <literal>-count</> value tells
The optional <literal>-count</> value tells
<function>spi_exec</function> the maximum number of rows
<function>spi_exec</function> the maximum number of rows
to process in the
query
. The effect of this is comparable to
to process in the
command
. The effect of this is comparable to
setting up
the query as a cursor and then saying <literal>FETCH n
</>.
setting up
a query as a cursor and then saying <literal>FETCH <replaceable>n</>
</>.
</para>
</para>
<para>
<para>
If the
query is a <literal>SELECT</> statement, the values of the statement's
If the
command is a <command>SELECT</> statement, the values of the
result columns are placed into Tcl variables named after the columns.
result columns are placed into Tcl variables named after the columns.
If the <literal>-array</> option is given, the column values are
If the <literal>-array</> option is given, the column values are
instead stored into the named associative array, with the
SELECT
instead stored into the named associative array, with the
column names used as array indexes.
column names used as array indexes.
</para>
</para>
<para>
<para>
If the
query is a SELECT
statement and no <replaceable>loop-body</>
If the
command is a <command>SELECT</>
statement and no <replaceable>loop-body</>
script is given, then only the first row of results are stored into
script is given, then only the first row of results are stored into
Tcl variables; remaining rows, if any, are ignored. No stor
e
occurs
Tcl variables; remaining rows, if any, are ignored. No stor
ing
occurs
if the
if the
SELECT returns no rows (t
his case can be detected by checking the
query returns no rows. (T
his case can be detected by checking the
result of <function>spi_exec</function>
).
For example,
result of <function>spi_exec</function>
.)
For example,
<programlisting>
<programlisting>
spi_exec "SELECT count(*) AS cnt FROM pg_proc"
spi_exec "SELECT count(*) AS cnt FROM pg_proc"
</programlisting>
</programlisting>
will set the Tcl variable <literal>$cnt</> to the number of rows in
will set the Tcl variable <literal>$cnt</> to the number of rows in
the <structname>pg_proc</> system catalog.
the <structname>pg_proc</> system catalog.
...
@@ -272,23 +272,23 @@ spi_exec "SELECT count(*) AS cnt FROM pg_proc"
...
@@ -272,23 +272,23 @@ spi_exec "SELECT count(*) AS cnt FROM pg_proc"
<para>
<para>
If the optional <replaceable>loop-body</> argument is given, it is
If the optional <replaceable>loop-body</> argument is given, it is
a piece of Tcl script that is executed once for each row in the
a piece of Tcl script that is executed once for each row in the
SELECT result (note:
<replaceable>loop-body</> is ignored if the given
query result. (
<replaceable>loop-body</> is ignored if the given
query is not a SELECT). The values of the current row's field
s
command is not a <command>SELECT</>.) The values of the current row's column
s
are stored into Tcl variables before each iteration. For example,
are stored into Tcl variables before each iteration. For example,
<programlisting>
<programlisting>
spi_exec -array C "SELECT * FROM pg_class" {
spi_exec -array C "SELECT * FROM pg_class" {
elog DEBUG "have table $C(relname)"
elog DEBUG "have table $C(relname)"
}
}
</programlisting>
</programlisting>
will print a
DEBUG log message for every row of pg_class
. This
will print a
log message for every row of <literal>pg_class</>
. This
feature works similarly to other Tcl looping constructs; in
feature works similarly to other Tcl looping constructs; in
particular <literal>continue</> and <literal>break</> work in the
particular <literal>continue</> and <literal>break</> work in the
usual way inside the loop body.
usual way inside the loop body.
</para>
</para>
<para>
<para>
If a
field of a SELECT result is NULL
, the target
If a
column of a query result is null
, the target
variable for it is <quote>unset</> rather than being set.
variable for it is <quote>unset</> rather than being set.
</para>
</para>
</listitem>
</listitem>
...
@@ -299,18 +299,18 @@ spi_exec -array C "SELECT * FROM pg_class" {
...
@@ -299,18 +299,18 @@ spi_exec -array C "SELECT * FROM pg_class" {
<listitem>
<listitem>
<para>
<para>
Prepares and saves a query plan for later execution. The saved plan
Prepares and saves a query plan for later execution. The saved plan
will be retained for the life of the current
backend
.
will be retained for the life of the current
session
.
</para>
</para>
<para>
<para>
The query may use
<firstterm>arguments</>, which are
placeholders for
The query may use
parameters, that is,
placeholders for
values to be supplied whenever the plan is actually executed.
values to be supplied whenever the plan is actually executed.
In the query string, refer to
argument
s
In the query string, refer to
parameter
s
by the symbols <literal>$1</literal> ... <literal>$
n
</literal>.
by the symbols <literal>$1</literal> ... <literal>$
<replaceable>n</replaceable>
</literal>.
If the query uses
arguments, the names of the argument
types
If the query uses
parameters, the names of the parameter
types
must be given as a Tcl list. (Write an empty list for
must be given as a Tcl list. (Write an empty list for
<replaceable>typelist</replaceable> if no
argument
s are used.)
<replaceable>typelist</replaceable> if no
parameter
s are used.)
Presently, the
argument
types must be identified by the internal
Presently, the
parameter
types must be identified by the internal
type names shown in
pg_type
; for example <literal>int4</> not
type names shown in
the system table <literal>pg_type</>
; for example <literal>int4</> not
<literal>integer</>.
<literal>integer</>.
</para>
</para>
<para>
<para>
...
@@ -325,24 +325,24 @@ spi_exec -array C "SELECT * FROM pg_class" {
...
@@ -325,24 +325,24 @@ spi_exec -array C "SELECT * FROM pg_class" {
<term><function>spi_execp</> <literal>?-count <replaceable>n</replaceable>? ?-array <replaceable>name</replaceable>? ?-nulls <replaceable>string</replaceable>? <replaceable>queryid</replaceable> ?<replaceable>value-list</replaceable>? ?<replaceable>loop-body</replaceable>?</literal></term>
<term><function>spi_execp</> <literal>?-count <replaceable>n</replaceable>? ?-array <replaceable>name</replaceable>? ?-nulls <replaceable>string</replaceable>? <replaceable>queryid</replaceable> ?<replaceable>value-list</replaceable>? ?<replaceable>loop-body</replaceable>?</literal></term>
<listitem>
<listitem>
<para>
<para>
Execute a query previously prepared with <function>spi_prepare</>.
Execute
s
a query previously prepared with <function>spi_prepare</>.
<replaceable>queryid</replaceable> is the ID returned by
<replaceable>queryid</replaceable> is the ID returned by
<function>spi_prepare</>. If the query references
argument
s,
<function>spi_prepare</>. If the query references
parameter
s,
a <replaceable>value-list</replaceable> must be supplied
: t
his
a <replaceable>value-list</replaceable> must be supplied
. T
his
is a Tcl list of actual values for the
arguments. This
must be
is a Tcl list of actual values for the
parameters. The list
must be
the same length as the
argument
type list previously given to
the same length as the
parameter
type list previously given to
<function>spi_prepare</>. Omit <replaceable>value-list</replaceable>
<function>spi_prepare</>. Omit <replaceable>value-list</replaceable>
if the query has no
argument
s.
if the query has no
parameter
s.
</para>
</para>
<para>
<para>
The optional value for <literal>-nulls</> is a string of spaces and
The optional value for <literal>-nulls</> is a string of spaces and
<literal>'n'</> characters telling <function>spi_execp</function>
<literal>'n'</> characters telling <function>spi_execp</function>
which of the
argument
s are null values. If given, it must have exactly the
which of the
parameter
s are null values. If given, it must have exactly the
same length as the <replaceable>value-list</replaceable>. If it
same length as the <replaceable>value-list</replaceable>. If it
is not given, all the
argument values are non-NULL
.
is not given, all the
parameter values are nonnull
.
</para>
</para>
<para>
<para>
Except for the way in which the query and its
argument
s are specified,
Except for the way in which the query and its
parameter
s are specified,
<function>spi_execp</> works just like <function>spi_exec</>.
<function>spi_execp</> works just like <function>spi_exec</>.
The <literal>-count</>, <literal>-array</>, and
The <literal>-count</>, <literal>-array</>, and
<replaceable>loop-body</replaceable> options are the same,
<replaceable>loop-body</replaceable> options are the same,
...
@@ -351,7 +351,7 @@ spi_exec -array C "SELECT * FROM pg_class" {
...
@@ -351,7 +351,7 @@ spi_exec -array C "SELECT * FROM pg_class" {
<para>
<para>
Here's an example of a PL/Tcl function using a prepared plan:
Here's an example of a PL/Tcl function using a prepared plan:
<programlisting>
<programlisting>
CREATE FUNCTION t1_count(integer, integer) RETURNS integer AS '
CREATE FUNCTION t1_count(integer, integer) RETURNS integer AS '
if {![ info exists GD(plan) ]} {
if {![ info exists GD(plan) ]} {
# prepare the saved plan on the first call
# prepare the saved plan on the first call
...
@@ -361,14 +361,14 @@ CREATE FUNCTION t1_count(integer, integer) RETURNS integer AS '
...
@@ -361,14 +361,14 @@ CREATE FUNCTION t1_count(integer, integer) RETURNS integer AS '
}
}
spi_execp -count 1 $GD(plan) [ list $1 $2 ]
spi_execp -count 1 $GD(plan) [ list $1 $2 ]
return $cnt
return $cnt
' LANGUAGE
'pltcl'
;
' LANGUAGE
pltcl
;
</programlisting>
</programlisting>
Note that each backslash that Tcl should see must be doubled when
Note that each backslash that Tcl should see must be doubled when
we type in the function, since the main parser processes
we type in the function, since the main parser processes
backslashes
too in CREATE FUNCTION
. We need backslashes inside
backslashes
, too, in <command>CREATE FUNCTION</>
. We need backslashes inside
the query string given to <function>spi_prepare</> to ensure that
the query string given to <function>spi_prepare</> to ensure that
the <literal>$
n
</> markers will be passed through to
the <literal>$
<replaceable>n</replaceable>
</> markers will be passed through to
<function>spi_prepare</> as-is, and not
<function>spi_prepare</> as-is, and not
replaced by Tcl variable substitution.
replaced by Tcl variable substitution.
</para>
</para>
...
@@ -383,8 +383,8 @@ CREATE FUNCTION t1_count(integer, integer) RETURNS integer AS '
...
@@ -383,8 +383,8 @@ CREATE FUNCTION t1_count(integer, integer) RETURNS integer AS '
<listitem>
<listitem>
<para>
<para>
Returns the OID of the row inserted by the last
Returns the OID of the row inserted by the last
<function>spi_exec</>
'd or <function>spi_execp</>'d query
,
<function>spi_exec</>
or <function>spi_execp</>
,
if th
at query was a single-row INSERT
. (If not, you get zero.)
if th
e command was a single-row <command>INSERT</>
. (If not, you get zero.)
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -395,18 +395,18 @@ CREATE FUNCTION t1_count(integer, integer) RETURNS integer AS '
...
@@ -395,18 +395,18 @@ CREATE FUNCTION t1_count(integer, integer) RETURNS integer AS '
<para>
<para>
Duplicates all occurrences of single quote and backslash characters
Duplicates all occurrences of single quote and backslash characters
in the given string. This may be used to safely quote strings
in the given string. This may be used to safely quote strings
that are to be inserted into SQL
querie
s given
that are to be inserted into SQL
command
s given
to <function>spi_exec</function> or
to <function>spi_exec</function> or
<function>spi_prepare</function>.
<function>spi_prepare</function>.
For example, think about a
query
string like
For example, think about a
n SQL command
string like
<programlisting>
<programlisting>
"SELECT '$val' AS ret"
"SELECT '$val' AS ret"
</programlisting>
</programlisting>
where the Tcl variable
val
actually contains
where the Tcl variable
<literal>val</>
actually contains
<literal>doesn't</literal>. This would result
<literal>doesn't</literal>. This would result
in the final
query
string
in the final
command
string
<programlisting>
<programlisting>
SELECT 'doesn't' AS ret
SELECT 'doesn't' AS ret
...
@@ -415,21 +415,21 @@ SELECT 'doesn't' AS ret
...
@@ -415,21 +415,21 @@ SELECT 'doesn't' AS ret
which would cause a parse error during
which would cause a parse error during
<function>spi_exec</function> or
<function>spi_exec</function> or
<function>spi_prepare</function>.
<function>spi_prepare</function>.
The submitted
query
should contain
The submitted
command
should contain
<programlisting>
<programlisting>
SELECT 'doesn''t' AS ret
SELECT 'doesn''t' AS ret
</programlisting>
</programlisting>
which can be formed in PL/Tcl
as
which can be formed in PL/Tcl
using
<programlisting>
<programlisting>
"SELECT '[ quote $val ]' AS ret"
"SELECT '[ quote $val ]' AS ret"
</programlisting>
</programlisting>
One advantage of <function>spi_execp</function> is that you don't
One advantage of <function>spi_execp</function> is that you don't
have to quote
argument values like this, since the argument
s are never
have to quote
parameter values like this, since the parameter
s are never
parsed as part of an SQL
query
string.
parsed as part of an SQL
command
string.
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -441,26 +441,27 @@ SELECT 'doesn''t' AS ret
...
@@ -441,26 +441,27 @@ SELECT 'doesn''t' AS ret
<term><function>elog</> <replaceable>level</replaceable> <replaceable>msg</replaceable></term>
<term><function>elog</> <replaceable>level</replaceable> <replaceable>msg</replaceable></term>
<listitem>
<listitem>
<para>
<para>
Emit a log or error message. Possible levels are
Emit
s
a log or error message. Possible levels are
<literal>DEBUG</>, <literal>LOG</>, <literal>INFO</>,
<literal>DEBUG</>, <literal>LOG</>, <literal>INFO</>,
<literal>NOTICE</>, <literal>WARNING</>, <literal>ERROR</>, and
<literal>NOTICE</>, <literal>WARNING</>, <literal>ERROR</>, and
<literal>FATAL</>. Most simply emit the given message just like
<literal>FATAL</>. Most simply emit the given message just like
the <literal>elog</>
backend
C function. <literal>ERROR</>
the <literal>elog</> C function. <literal>ERROR</>
raises an error condition: further execution of the function is
raises an error condition: further execution of the function is
abandoned, and the current transaction is aborted.
abandoned, and the current transaction is aborted.
<literal>FATAL</> aborts the transaction and causes the current
<literal>FATAL</> aborts the transaction and causes the current
backend to shut down (t
here is probably no good reason to use
session to shut down. (T
here is probably no good reason to use
this error level in PL/Tcl functions, but it's provided for
this error level in PL/Tcl functions, but it's provided for
completeness
).
completeness
.)
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
</variablelist>
</variablelist>
</para>
</sect
2
>
</sect
1
>
<sect
2
>
<sect
1 id="pltcl-trigger"
>
<title>Trigger Procedures in PL/Tcl</title>
<title>Trigger Procedures in PL/Tcl</title>
<indexterm>
<indexterm>
...
@@ -469,8 +470,8 @@ SELECT 'doesn''t' AS ret
...
@@ -469,8 +470,8 @@ SELECT 'doesn''t' AS ret
</indexterm>
</indexterm>
<para>
<para>
Trigger procedures can be written in PL/Tcl.
As is customary in
Trigger procedures can be written in PL/Tcl.
<productname>PostgreSQL</productname>
, a procedure that'
s to be called
<productname>PostgreSQL</productname>
requires that a procedure that i
s to be called
as a trigger must be declared as a function with no arguments
as a trigger must be declared as a function with no arguments
and a return type of <literal>trigger</>.
and a return type of <literal>trigger</>.
</para>
</para>
...
@@ -481,16 +482,16 @@ SELECT 'doesn''t' AS ret
...
@@ -481,16 +482,16 @@ SELECT 'doesn''t' AS ret
<variablelist>
<variablelist>
<varlistentry>
<varlistentry>
<term><
replaceable class="Parameter">$TG_name</replaceabl
e></term>
<term><
varname>$TG_name</varnam
e></term>
<listitem>
<listitem>
<para>
<para>
The name of the trigger from the
CREATE TRIGGER
statement.
The name of the trigger from the
<command>CREATE TRIGGER</command>
statement.
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
<varlistentry>
<term><
replaceable class="Parameter">$TG_relid</replaceabl
e></term>
<term><
varname>$TG_relid</varnam
e></term>
<listitem>
<listitem>
<para>
<para>
The object ID of the table that caused the trigger procedure
The object ID of the table that caused the trigger procedure
...
@@ -500,20 +501,20 @@ SELECT 'doesn''t' AS ret
...
@@ -500,20 +501,20 @@ SELECT 'doesn''t' AS ret
</varlistentry>
</varlistentry>
<varlistentry>
<varlistentry>
<term><
replaceable class="Parameter">$TG_relatts</replaceabl
e></term>
<term><
varname>$TG_relatts</varnam
e></term>
<listitem>
<listitem>
<para>
<para>
A Tcl list of the table
field
names, prefixed with an empty list
A Tcl list of the table
column
names, prefixed with an empty list
element. So looking up a
n element
name in the list with <application>Tcl</>'s
element. So looking up a
column
name in the list with <application>Tcl</>'s
<function>lsearch</> command returns the element's number starting
<function>lsearch</> command returns the element's number starting
with 1 for the first column, the same way the
field
s are customarily
with 1 for the first column, the same way the
column
s are customarily
numbered in <productname>PostgreSQL</productname>.
numbered in <productname>PostgreSQL</productname>.
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
<varlistentry>
<term><
replaceable class="Parameter">$TG_when</replaceabl
e></term>
<term><
varname>$TG_when</varnam
e></term>
<listitem>
<listitem>
<para>
<para>
The string <literal>BEFORE</> or <literal>AFTER</> depending on the
The string <literal>BEFORE</> or <literal>AFTER</> depending on the
...
@@ -523,7 +524,7 @@ SELECT 'doesn''t' AS ret
...
@@ -523,7 +524,7 @@ SELECT 'doesn''t' AS ret
</varlistentry>
</varlistentry>
<varlistentry>
<varlistentry>
<term><
replaceable class="Parameter">$TG_level</replaceabl
e></term>
<term><
varname>$TG_level</varnam
e></term>
<listitem>
<listitem>
<para>
<para>
The string <literal>ROW</> or <literal>STATEMENT</> depending on the
The string <literal>ROW</> or <literal>STATEMENT</> depending on the
...
@@ -533,44 +534,46 @@ SELECT 'doesn''t' AS ret
...
@@ -533,44 +534,46 @@ SELECT 'doesn''t' AS ret
</varlistentry>
</varlistentry>
<varlistentry>
<varlistentry>
<term><
replaceable class="Parameter">$TG_op</replaceabl
e></term>
<term><
varname>$TG_op</varnam
e></term>
<listitem>
<listitem>
<para>
<para>
The string <literal>INSERT</>, <literal>UPDATE</> or
The string <literal>INSERT</>, <literal>UPDATE</>
,
or
<literal>DELETE</> depending on the type of trigger call.
<literal>DELETE</> depending on the type of trigger call.
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
<varlistentry>
<term><
replaceable class="Parameter">$NEW</replaceabl
e></term>
<term><
varname>$NEW</varnam
e></term>
<listitem>
<listitem>
<para>
<para>
An associative array containing the values of the new table row for
An associative array containing the values of the new table
INSERT/UPDATE actions, or empty for DELETE. The array is indexed
row for <command>INSERT</> or <command>UPDATE</> actions, or
by field name. Fields that are NULL will not appear in the array!
empty for <command>DELETE</>. The array is indexed by column
name. Columns that are null will not appear in the array.
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
<varlistentry>
<term><
replaceable class="Parameter">$OLD</replaceabl
e></term>
<term><
varname>$OLD</varnam
e></term>
<listitem>
<listitem>
<para>
<para>
An associative array containing the values of the old table row for
An associative array containing the values of the old table
UPDATE/DELETE actions, or empty for INSERT. The array is indexed
row for <command>UPDATE</> or <command>DELETE</> actions, or
by field name. Fields that are NULL will not appear in the array!
empty for <command>INSERT</>. The array is indexed by column
name. Columns that are null will not appear in the array.
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
<varlistentry>
<varlistentry>
<term><
replaceable class="Parameter">$args</replaceabl
e></term>
<term><
varname>$args</varnam
e></term>
<listitem>
<listitem>
<para>
<para>
A Tcl list of the arguments to the procedure as given in the
A Tcl list of the arguments to the procedure as given in the
CREATE TRIGGER
statement. These arguments are also accessible as
<command>CREATE TRIGGER</command>
statement. These arguments are also accessible as
<literal>$1</literal> ... <literal>$
n
</literal> in the procedure body.
<literal>$1</literal> ... <literal>$
<replaceable>n</replaceable>
</literal> in the procedure body.
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -582,22 +585,22 @@ SELECT 'doesn''t' AS ret
...
@@ -582,22 +585,22 @@ SELECT 'doesn''t' AS ret
The return value from a trigger procedure can be one of the strings
The return value from a trigger procedure can be one of the strings
<literal>OK</> or <literal>SKIP</>, or a list as returned by the
<literal>OK</> or <literal>SKIP</>, or a list as returned by the
<literal>array get</> Tcl command. If the return value is <literal>OK</>,
<literal>array get</> Tcl command. If the return value is <literal>OK</>,
the operation (
INSERT/UPDATE/DELETE
) that fired the trigger will proceed
the operation (
<command>INSERT</>/<command>UPDATE</>/<command>DELETE</>
) that fired the trigger will proceed
normally. <literal>SKIP</> tells the trigger manager to silently suppress
normally. <literal>SKIP</> tells the trigger manager to silently suppress
the operation for this row. If a list is returned, it tells PL/Tcl to
the operation for this row. If a list is returned, it tells PL/Tcl to
return a modified row to the trigger manager that will be inserted
return a modified row to the trigger manager that will be inserted
instead of the one given in
$NEW (this works for INSERT/UPDATE
instead of the one given in
<varname>$NEW</>. (This works for <command>INSERT</> and <command>UPDATE</>
only
).
Needless to say that all this is only meaningful when the trigger
only
.)
Needless to say that all this is only meaningful when the trigger
is
BEFORE and FOR EACH ROW
; otherwise the return value is ignored.
is
<literal>BEFORE</> and <command>FOR EACH ROW</>
; otherwise the return value is ignored.
</para>
</para>
<para>
<para>
Here's a little example trigger procedure that forces an integer value
Here's a little example trigger procedure that forces an integer value
in a table to keep track of the number of updates that are performed on the
in a table to keep track of the number of updates that are performed on the
row. For new rows inserted, the value is initialized to 0 and then
row. For new rows inserted, the value is initialized to 0 and then
incremented on every update operation
:
incremented on every update operation
.
<programlisting>
<programlisting>
CREATE FUNCTION trigfunc_modcount() RETURNS
TRIGGER
AS '
CREATE FUNCTION trigfunc_modcount() RETURNS
trigger
AS '
switch $TG_op {
switch $TG_op {
INSERT {
INSERT {
set NEW($1) 0
set NEW($1) 0
...
@@ -611,24 +614,24 @@ CREATE FUNCTION trigfunc_modcount() RETURNS TRIGGER AS '
...
@@ -611,24 +614,24 @@ CREATE FUNCTION trigfunc_modcount() RETURNS TRIGGER AS '
}
}
}
}
return [array get NEW]
return [array get NEW]
' LANGUAGE
'pltcl'
;
' LANGUAGE
pltcl
;
CREATE TABLE mytab (num integer, description text, modcnt integer);
CREATE TABLE mytab (num integer, description text, modcnt integer);
CREATE TRIGGER trig_mytab_modcount BEFORE INSERT OR UPDATE ON mytab
CREATE TRIGGER trig_mytab_modcount BEFORE INSERT OR UPDATE ON mytab
FOR EACH ROW EXECUTE PROCEDURE trigfunc_modcount('modcnt');
FOR EACH ROW EXECUTE PROCEDURE trigfunc_modcount('modcnt');
</programlisting>
</programlisting>
Notice that the trigger procedure itself does not know the column
Notice that the trigger procedure itself does not know the column
name; that's supplied from the trigger arguments. This lets the
name; that's supplied from the trigger arguments. This lets the
trigger procedure be re
-
used with different tables.
trigger procedure be reused with different tables.
</para>
</para>
</sect
2
>
</sect
1
>
<sect
2
>
<sect
1 id="pltcl-unknown"
>
<title>
Modules and the <function>unknown</> command</title>
<title>Modules and the <function>unknown</> command</title>
<para>
<para>
PL/Tcl has support for auto
-
loading Tcl code when used.
PL/Tcl has support for autoloading Tcl code when used.
It recognizes a special table, <literal>pltcl_modules</>, which
It recognizes a special table, <literal>pltcl_modules</>, which
is presumed to contain modules of Tcl code. If this table
is presumed to contain modules of Tcl code. If this table
exists, the module <literal>unknown</> is fetched from the table
exists, the module <literal>unknown</> is fetched from the table
...
@@ -638,7 +641,7 @@ CREATE TRIGGER trig_mytab_modcount BEFORE INSERT OR UPDATE ON mytab
...
@@ -638,7 +641,7 @@ CREATE TRIGGER trig_mytab_modcount BEFORE INSERT OR UPDATE ON mytab
<para>
<para>
While the <literal>unknown</> module could actually contain any
While the <literal>unknown</> module could actually contain any
initialization script you need, it normally defines a Tcl
initialization script you need, it normally defines a Tcl
<
quote
>unknown</> procedure that is invoked whenever Tcl does
<
function
>unknown</> procedure that is invoked whenever Tcl does
not recognize an invoked procedure name. <application>PL/Tcl</>'s standard version
not recognize an invoked procedure name. <application>PL/Tcl</>'s standard version
of this procedure tries to find a module in <literal>pltcl_modules</>
of this procedure tries to find a module in <literal>pltcl_modules</>
that will define the required procedure. If one is found, it is
that will define the required procedure. If one is found, it is
...
@@ -653,7 +656,7 @@ CREATE TRIGGER trig_mytab_modcount BEFORE INSERT OR UPDATE ON mytab
...
@@ -653,7 +656,7 @@ CREATE TRIGGER trig_mytab_modcount BEFORE INSERT OR UPDATE ON mytab
support scripts to maintain these tables:
support scripts to maintain these tables:
<command>pltcl_loadmod</>, <command>pltcl_listmod</>,
<command>pltcl_loadmod</>, <command>pltcl_listmod</>,
<command>pltcl_delmod</>, as well as source for the standard
<command>pltcl_delmod</>, as well as source for the standard
unknown module
<filename>share/unknown.pltcl</>. This module
<literal>unknown</> module in
<filename>share/unknown.pltcl</>. This module
must be loaded
must be loaded
into each database initially to support the autoloading mechanism.
into each database initially to support the autoloading mechanism.
</para>
</para>
...
@@ -662,9 +665,9 @@ CREATE TRIGGER trig_mytab_modcount BEFORE INSERT OR UPDATE ON mytab
...
@@ -662,9 +665,9 @@ CREATE TRIGGER trig_mytab_modcount BEFORE INSERT OR UPDATE ON mytab
must be readable by all, but it is wise to make them owned and
must be readable by all, but it is wise to make them owned and
writable only by the database administrator.
writable only by the database administrator.
</para>
</para>
</sect
2
>
</sect
1
>
<sect
2
>
<sect
1 id="pltcl-procnames"
>
<title>Tcl Procedure Names</title>
<title>Tcl Procedure Names</title>
<para>
<para>
...
@@ -674,16 +677,14 @@ CREATE TRIGGER trig_mytab_modcount BEFORE INSERT OR UPDATE ON mytab
...
@@ -674,16 +677,14 @@ CREATE TRIGGER trig_mytab_modcount BEFORE INSERT OR UPDATE ON mytab
differ. Tcl, however, requires all procedure names to be distinct.
differ. Tcl, however, requires all procedure names to be distinct.
PL/Tcl deals with this by making the internal Tcl procedure names contain
PL/Tcl deals with this by making the internal Tcl procedure names contain
the object
the object
ID of the
procedure's <structname>pg_proc</> row
as part of their name. Thus,
ID of the
function from the system table <structname>pg_proc</>
as part of their name. Thus,
<productname>PostgreSQL</productname> functions with the same name
<productname>PostgreSQL</productname> functions with the same name
and different argument types will be different Tcl procedures too. This
and different argument types will be different Tcl procedures
,
too. This
is not normally a concern for a PL/Tcl programmer, but it might be visible
is not normally a concern for a PL/Tcl programmer, but it might be visible
when debugging.
when debugging.
</para>
</para>
</sect2>
</sect1>
</sect1>
</chapter>
</chapter>
<!-- Keep this comment at the end of the file
<!-- Keep this comment at the end of the file
...
...
doc/src/sgml/pygresql.sgml
View file @
a8cb3368
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/Attic/pygresql.sgml,v 1.
9 2002/12/12 22:49:27 momjian
Exp $ -->
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/Attic/pygresql.sgml,v 1.
10 2003/04/07 01:29:25 petere
Exp $ -->
<chapter id="pygresql">
<chapter id="pygresql">
<title><application>PyGreSQL</application> - <application>Python</application> Interface</title>
<title><application>PyGreSQL</application> - <application>Python</application> Interface</title>
...
@@ -334,13 +334,10 @@ make && make install
...
@@ -334,13 +334,10 @@ make && make install
<acronym>API</acronym> at <ulink
<acronym>API</acronym> at <ulink
url="http://www.python.org/topics/database/DatabaseAPI-2.0.html"
url="http://www.python.org/topics/database/DatabaseAPI-2.0.html"
>http://www.python.org/topics/database/DatabaseAPI-2.0.html</ulink>.
>http://www.python.org/topics/database/DatabaseAPI-2.0.html</ulink>.
</para>
<para>
A tutorial-like introduction to the <acronym>DB-API</acronym> can be
A tutorial-like introduction to the <acronym>DB-API</acronym> can be
found at <ulink
found at <ulink
url="http://www2.linuxjournal.com/lj-issues/issue49/2605.html"
url="http://www2.linuxjournal.com/lj-issues/issue49/2605.html"
>http://www2.linuxjournal.com/lj-issues/issue49/2605.html</ulink>
>http://www2.linuxjournal.com/lj-issues/issue49/2605.html</ulink>
.
</para>
</para>
<sect1 id="pygresql-pg">
<sect1 id="pygresql-pg">
...
@@ -365,16 +362,15 @@ make && make install
...
@@ -365,16 +362,15 @@ make && make install
<listitem>
<listitem>
<para>
<para>
<classname>pgqueryobject</classname>
that
handles query results.
<classname>pgqueryobject</classname>
, which
handles query results.
</para>
</para>
</listitem>
</listitem>
</itemizedlist>
</itemizedlist>
</para>
</para>
<para>
<para>
If you want to see a simple example of the use of some of these
If you want to see a simple example of the use this module,
functions, see <ulink url="http://www.druid.net/rides"
see <ulink url="http://www.druid.net/rides"></ulink> where you can find a link at the
>http://www.druid.net/rides</ulink> where you can find a link at the
bottom to the actual <application>Python</application> code for the
bottom to the actual <application>Python</application> code for the
page.
page.
</para>
</para>
...
@@ -395,9 +391,9 @@ make && make install
...
@@ -395,9 +391,9 @@ make && make install
<term><varname>INV_WRITE</varname></term>
<term><varname>INV_WRITE</varname></term>
<listitem>
<listitem>
<para>
<para>
l
arge objects access modes, used by
L
arge objects access modes, used by
<function>(pgobject.)locreate</function> and
<function>(pgobject.)locreate</function> and
<function>(pglarge.)open</function>
.
<function>(pglarge.)open</function>
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -408,7 +404,7 @@ make && make install
...
@@ -408,7 +404,7 @@ make && make install
<term><varname>SEEK_END</varname></term>
<term><varname>SEEK_END</varname></term>
<listitem>
<listitem>
<para>
<para>
positional flags, used by <function>(pglarge.)seek</function>.
Positional flags, used by <function>(pglarge.)seek</function>
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -418,7 +414,7 @@ make && make install
...
@@ -418,7 +414,7 @@ make && make install
<term><varname>__version__</varname></term>
<term><varname>__version__</varname></term>
<listitem>
<listitem>
<para>
<para>
c
onstants that give the current version
C
onstants that give the current version
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -443,13 +439,13 @@ make && make install
...
@@ -443,13 +439,13 @@ make && make install
to handle general connection parameters without heavy code in your
to handle general connection parameters without heavy code in your
programs. You can prompt the user for a value, put it in the
programs. You can prompt the user for a value, put it in the
default variable, and forget it, without having to modify your
default variable, and forget it, without having to modify your
environment. The support for default variables can be disabled by
environment. The support for default variables can be disabled
at build time
by
setting the <option>-DNO_DEF_VAR</option> option in the Python
setting the <option>-DNO_DEF_VAR</option> option in the Python
<filename>Setup</> file. Methods relative to this are specified by the tag [DV].
<filename>Setup</> file. Methods relative to this are specified by the tag [DV].
</para>
</para>
<para>
<para>
All
variabl
es are set to <symbol>None</symbol> at module
All
default valu
es are set to <symbol>None</symbol> at module
initialization, specifying that standard environment variables
initialization, specifying that standard environment variables
should be used.
should be used.
</para>
</para>
...
@@ -478,7 +474,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
...
@@ -478,7 +474,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
<term><parameter>dbname</parameter></term>
<term><parameter>dbname</parameter></term>
<listitem>
<listitem>
<para>Name of connected database (string/<symbol>None</>)
.
</para>
<para>Name of connected database (string/<symbol>None</>)</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -486,7 +482,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
...
@@ -486,7 +482,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
<term><parameter>host</parameter></term>
<term><parameter>host</parameter></term>
<listitem>
<listitem>
<para>Name of the server host (string/<symbol>None</>)
.
</para>
<para>Name of the server host (string/<symbol>None</>)</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -494,7 +490,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
...
@@ -494,7 +490,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
<term><parameter>port</parameter></term>
<term><parameter>port</parameter></term>
<listitem>
<listitem>
<para>Port used by the database server (integer/-1)
.
</para>
<para>Port used by the database server (integer/-1)</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -503,7 +499,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
...
@@ -503,7 +499,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
<listitem>
<listitem>
<para>
<para>
Options for the server (string/<symbol>None</>)
.
Options for the server (string/<symbol>None</>)
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -513,8 +509,8 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
...
@@ -513,8 +509,8 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
<listitem>
<listitem>
<para>
<para>
File or
tty for optional debug output from backend
File or
TTY for optional debug output from server
(string/<symbol>None</>)
.
(string/<symbol>None</>)
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -524,7 +520,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
...
@@ -524,7 +520,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
<listitem>
<listitem>
<para>
<para>
<productname>PostgreSQL</productname> user (string/<symbol>None</>)
.
<productname>PostgreSQL</productname> user (string/<symbol>None</>)
</para>
</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
...
@@ -533,7 +529,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
...
@@ -533,7 +529,7 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
<term><parameter>passwd</parameter></term>
<term><parameter>passwd</parameter></term>
<listitem>
<listitem>
<para>Password for user (string/<symbol>None</>)
.
</para>
<para>Password for user (string/<symbol>None</>)</para>
</listitem>
</listitem>
</varlistentry>
</varlistentry>
</variablelist>
</variablelist>
...
@@ -601,12 +597,11 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
...
@@ -601,12 +597,11 @@ connect(<optional><parameter>dbname</parameter></optional>, <optional><parameter
<para>
<para>
This method opens a connection to a specified database on a given
This method opens a connection to a specified database on a given
<productname>PostgreSQL</productname> server. You can use
<productname>PostgreSQL</productname> server. The arguments can be
key words here, as described in the
given using key words here. The names of the
<application>Python</application> tutorial. The names of the
key words are the name of the parameters given in the syntax
key words are the name of the parameters given in the syntax
line. For a precise description of the parameters, please refer
line. For a precise description of the parameters, please refer
to
the <productname>PostgreSQL</productname> user manual
.
to
<xref linkend="libpq">
.
</para>
</para>
</refsect1>
</refsect1>
...
...
doc/src/sgml/xplang.sgml
View file @
a8cb3368
<!--
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/xplang.sgml,v 1.2
0 2003/01/31 00:10:51 tgl
Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/xplang.sgml,v 1.2
1 2003/04/07 01:29:26 petere
Exp $
-->
-->
<chapter id="xplang">
<chapter id="xplang">
<title id="xplang-title">Procedural Languages</title>
<title id="xplang-title">Procedural Languages</title>
<sect1 id="xplang-intro">
<title>Introduction</title>
<para>
<para>
<productname>PostgreSQL</productname> allows users to add new
<productname>PostgreSQL</productname> allows users to add new
programming languages to be available for writing functions and
programming languages to be available for writing functions and
...
@@ -21,7 +18,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/xplang.sgml,v 1.20 2003/01/31 00:10:51 tgl
...
@@ -21,7 +18,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/xplang.sgml,v 1.20 2003/01/31 00:10:51 tgl
could serve as <quote>glue</quote> between
could serve as <quote>glue</quote> between
<productname>PostgreSQL</productname> and an existing implementation
<productname>PostgreSQL</productname> and an existing implementation
of a programming language. The handler itself is a special
of a programming language. The handler itself is a special
programming
language function compiled into a shared object and
C
language function compiled into a shared object and
loaded on demand.
loaded on demand.
</para>
</para>
...
@@ -31,7 +28,6 @@ $Header: /cvsroot/pgsql/doc/src/sgml/xplang.sgml,v 1.20 2003/01/31 00:10:51 tgl
...
@@ -31,7 +28,6 @@ $Header: /cvsroot/pgsql/doc/src/sgml/xplang.sgml,v 1.20 2003/01/31 00:10:51 tgl
available in the standard <productname>PostgreSQL</productname>
available in the standard <productname>PostgreSQL</productname>
distribution, which can serve as examples.
distribution, which can serve as examples.
</para>
</para>
</sect1>
<sect1 id="xplang-install">
<sect1 id="xplang-install">
<title>Installing Procedural Languages</title>
<title>Installing Procedural Languages</title>
...
@@ -39,22 +35,24 @@ $Header: /cvsroot/pgsql/doc/src/sgml/xplang.sgml,v 1.20 2003/01/31 00:10:51 tgl
...
@@ -39,22 +35,24 @@ $Header: /cvsroot/pgsql/doc/src/sgml/xplang.sgml,v 1.20 2003/01/31 00:10:51 tgl
<para>
<para>
A procedural language must be <quote>installed</quote> into each
A procedural language must be <quote>installed</quote> into each
database where it is to be used. But procedural languages installed in
database where it is to be used. But procedural languages installed in
the
template1 database
are automatically available in all
the
database <literal>template1</>
are automatically available in all
subsequently created databases. So the database administrator can
subsequently created databases. So the database administrator can
decide which languages are available in which databases
,
and can make
decide which languages are available in which databases and can make
some languages available by default if he chooses.
some languages available by default if he chooses.
</para>
</para>
<para>
<para>
For the languages supplied with the standard distribution, the
For the languages supplied with the standard distribution, the
shell script <filename>createlang</filename> may be used instead
program <command>createlang</command> may be used to install the
of carrying out the details by hand. For example, to install <application>PL/pgSQL</application>
language instead of carrying out the details by hand. For
into the template1 database, use
example, to install the language
<application>PL/pgSQL</application> into the database
<literal>template1</>, use
<programlisting>
<programlisting>
createlang plpgsql template1
createlang plpgsql template1
</programlisting>
</programlisting>
The manual procedure described below is only recommended for
The manual procedure described below is only recommended for
installing custom languages that <
filename>createlang</filename
>
installing custom languages that <
command>createlang</command
>
does not know about.
does not know about.
</para>
</para>
...
@@ -64,8 +62,11 @@ createlang plpgsql template1
...
@@ -64,8 +62,11 @@ createlang plpgsql template1
</title>
</title>
<para>
<para>
A procedural language is installed in the database in three
A procedural language is installed in a database in three steps,
steps, which must be carried out by a database superuser.
which must be carried out by a database superuser. The
<command>createlang</command> programm automates <xref
linkend="xplang-install-cr1"> and <xref
linkend="xplang-install-cr2">.
</para>
</para>
<step performance="required">
<step performance="required">
...
@@ -81,12 +82,13 @@ createlang plpgsql template1
...
@@ -81,12 +82,13 @@ createlang plpgsql template1
<para>
<para>
The handler must be declared with the command
The handler must be declared with the command
<synopsis>
<synopsis>
CREATE FUNCTION <replaceable>handler_function_name</replaceable> ()
CREATE FUNCTION <replaceable>handler_function_name</replaceable>()
RETURNS LANGUAGE_HANDLER AS
RETURNS language_handler
'<replaceable>path-to-shared-object</replaceable>' LANGUAGE C;
AS '<replaceable>path-to-shared-object</replaceable>'
LANGUAGE C;
</synopsis>
</synopsis>
The special return type of <type>
LANGUAGE_HANDLER
</type> tells
The special return type of <type>
language_handler
</type> tells
the database that this function does not return one of
the database
system
that this function does not return one of
the defined <acronym>SQL</acronym> data types and is not directly usable
the defined <acronym>SQL</acronym> data types and is not directly usable
in <acronym>SQL</acronym> statements.
in <acronym>SQL</acronym> statements.
</para>
</para>
...
@@ -99,7 +101,7 @@ CREATE FUNCTION <replaceable>handler_function_name</replaceable> ()
...
@@ -99,7 +101,7 @@ CREATE FUNCTION <replaceable>handler_function_name</replaceable> ()
CREATE <optional>TRUSTED</optional> <optional>PROCEDURAL</optional> LANGUAGE <replaceable>language-name</replaceable>
CREATE <optional>TRUSTED</optional> <optional>PROCEDURAL</optional> LANGUAGE <replaceable>language-name</replaceable>
HANDLER <replaceable>handler_function_name</replaceable>;
HANDLER <replaceable>handler_function_name</replaceable>;
</synopsis>
</synopsis>
The optional key word <literal>TRUSTED</literal>
tells whether
The optional key word <literal>TRUSTED</literal>
specifies that
ordinary database users that have no superuser privileges should
ordinary database users that have no superuser privileges should
be allowed to use this language to create functions and trigger
be allowed to use this language to create functions and trigger
procedures. Since PL functions are executed inside the database
procedures. Since PL functions are executed inside the database
...
@@ -119,20 +121,12 @@ CREATE <optional>TRUSTED</optional> <optional>PROCEDURAL</optional> LANGUAGE <re
...
@@ -119,20 +121,12 @@ CREATE <optional>TRUSTED</optional> <optional>PROCEDURAL</optional> LANGUAGE <re
</procedure>
</procedure>
<para>
<para>
In a default <productname>PostgreSQL</productname> installation,
<xref linkend="xplang-install-example"> shows how the manual
the handler for the <application>PL/pgSQL</application> language
installation procedure would work with the language
is built and installed into the <quote>library</quote>
<application>PL/pgSQL</application>.
directory. If <application>Tcl/Tk</> support is configured in, the handlers for
<application>PL/Tcl</> and <application>PL/TclU</> are also built and installed in the same
location. Likewise, the <application>PL/Perl</> and <application>PL/PerlU</> handlers are built
and installed if Perl support is configured, and <application>PL/Python</> is
installed if Python support is configured. The
<filename>createlang</filename> script automates <xref
linkend="xplang-install-cr1"> and <xref
linkend="xplang-install-cr2"> described above.
</para>
</para>
<example>
<example
id="xplang-install-example"
>
<title>Manual Installation of <application>PL/pgSQL</application></title>
<title>Manual Installation of <application>PL/pgSQL</application></title>
<para>
<para>
...
@@ -140,7 +134,7 @@ CREATE <optional>TRUSTED</optional> <optional>PROCEDURAL</optional> LANGUAGE <re
...
@@ -140,7 +134,7 @@ CREATE <optional>TRUSTED</optional> <optional>PROCEDURAL</optional> LANGUAGE <re
shared object for the <application>PL/pgSQL</application> language's call handler function.
shared object for the <application>PL/pgSQL</application> language's call handler function.
<programlisting>
<programlisting>
CREATE FUNCTION plpgsql_call_handler
() RETURNS LANGUAGE_HANDLER
AS
CREATE FUNCTION plpgsql_call_handler
() RETURNS language_handler
AS
'$libdir/plpgsql' LANGUAGE C;
'$libdir/plpgsql' LANGUAGE C;
</programlisting>
</programlisting>
</para>
</para>
...
@@ -157,6 +151,17 @@ CREATE TRUSTED PROCEDURAL LANGUAGE plpgsql
...
@@ -157,6 +151,17 @@ CREATE TRUSTED PROCEDURAL LANGUAGE plpgsql
</para>
</para>
</example>
</example>
<para>
In a default <productname>PostgreSQL</productname> installation,
the handler for the <application>PL/pgSQL</application> language
is built and installed into the <quote>library</quote>
directory. If <application>Tcl/Tk</> support is configured in, the handlers for
<application>PL/Tcl</> and <application>PL/TclU</> are also built and installed in the same
location. Likewise, the <application>PL/Perl</> and <application>PL/PerlU</> handlers are built
and installed if Perl support is configured, and <application>PL/Python</> is
installed if Python support is configured.
</para>
</sect1>
</sect1>
</chapter>
</chapter>
...
...
Write
Preview
Markdown
is supported
0%
Try again
or
attach a new file
Attach a file
Cancel
You are about to add
0
people
to the discussion. Proceed with caution.
Finish editing this message first!
Cancel
Please
register
or
sign in
to comment