Commit b8052309 authored by Thomas G. Lockhart's avatar Thomas G. Lockhart

Markup fixes.

Update for v6.5 release.
parent 7d831b53
<Sect1> <sect1 id="about">
<Title>About This Release</Title> <title>About This Release</title>
<Para> <para>
<ProductName>PostgreSQL</ProductName> is available without cost. This manual <productname>PostgreSQL</productname> is available without cost. This manual
describes version 6.4 of <ProductName>PostgreSQL</ProductName>. describes version 6.5 of <productname>PostgreSQL</productname>.
</Para> </para>
<Para>
We will use <ProductName>Postgres</ProductName> <para>
to mean the version distributed as <ProductName>PostgreSQL</ProductName>. We will use <productname>Postgres</productname>
</Para> to mean the version distributed as <productname>PostgreSQL</productname>.
<Para> </para>
Check the Administrator's Guide for a list of currently supported machines.
In general, <para>
<ProductName>Postgres</ProductName> is portable to any Unix/Posix-compatible system Check the Administrator's Guide for a list of currently supported machines.
with full libc library support. In general,
</Para> <productname>Postgres</productname> is portable to any Unix/Posix-compatible system
</Sect1> with full libc library support.
</para>
</sect1>
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...@@ -19,10 +19,10 @@ ...@@ -19,10 +19,10 @@
Unlike most other database systems which use locks for concurrency control, Unlike most other database systems which use locks for concurrency control,
<productname>Postgres</productname> <productname>Postgres</productname>
maintains data consistency by using a multiversion model. maintains data consistency by using a multiversion model.
This means that while querying database each transaction sees This means that while querying a database each transaction sees
a snapshot of data (a <firstterm>database version</firstterm>) a snapshot of data (a <firstterm>database version</firstterm>)
as it was some as it was some
time ago, regardless of the current state of data queried. time ago, regardless of the current state of the underlying data.
This protects the transaction from viewing inconsistent data that This protects the transaction from viewing inconsistent data that
could be caused by (other) concurrent transaction updates on the same could be caused by (other) concurrent transaction updates on the same
data rows, providing <firstterm>transaction isolation</firstterm> data rows, providing <firstterm>transaction isolation</firstterm>
...@@ -87,81 +87,88 @@ ...@@ -87,81 +87,88 @@
</para> </para>
<para> <para>
Accordingly, the four isolation levels are defined to be: The four isolation levels and the corresponding behaviors are described below.
<segmentedlist> <table tocentry="1">
<segtitle> <title><productname>Postgres</productname> Isolation Levels</title>
Isolation Level <titleabbrev>Isolation Levels</titleabbrev>
</segtitle> <tgroup cols="4">
<segtitle> <thead>
Dirty Read <row>
</segtitle> <entry>
<segtitle> Dirty Read
Non-Repeatable Read </entry>
</segtitle> <entry>
<segtitle> Non-Repeatable Read
Phantom Read </entry>
</segtitle> <entry>
<seglistitem> Phantom Read
<seg> </entry>
Read uncommitted </row>
</seg> </thead>
<seg> <tbody>
Possible <row>
</seg> <entry>
<seg> Read uncommitted
Possible </entry>
</seg> <entry>
<seg> Possible
Possible </entry>
</seg> <entry>
</seglistitem> Possible
</entry>
<seglistitem> <entry>
<seg> Possible
Read committed </entry>
</seg> </row>
<seg>
Not possible <row>
</seg> <entry>
<seg> Read committed
Possible </entry>
</seg> <entry>
<seg> Not possible
Possible </entry>
</seg> <entry>
</seglistitem> Possible
</entry>
<seglistitem> <entry>
<seg> Possible
Repeatable read </entry>
</seg> </row>
<seg>
Not possible <row>
</seg> <entry>
<seg> Repeatable read
Not possible </entry>
</seg> <entry>
<seg> Not possible
Possible </entry>
</seg> <entry>
</seglistitem> Not possible
</entry>
<seglistitem> <entry>
<seg> Possible
Serializable </entry>
</seg> </row>
<seg>
Not possible <row>
</seg> <entry>
<seg> Serializable
Not possible </entry>
</seg> <entry>
<seg> Not possible
Not possible </entry>
</seg> <entry>
</seglistitem> Not possible
</segmentedlist> </entry>
<entry>
Not possible
</entry>
</row>
</tbody>
</tgroup>
</table>
<productname>Postgres</productname> <productname>Postgres</productname>
offers the read committed and serializable isolation levels. offers the read committed and serializable isolation levels.
...@@ -172,7 +179,8 @@ ...@@ -172,7 +179,8 @@
<title>Read Committed Isolation Level</title> <title>Read Committed Isolation Level</title>
<para> <para>
This is the default isolation level in <productname>Postgres</productname>. <firstterm>Read Committed</firstterm>
is the default isolation level in <productname>Postgres</productname>.
When a transaction runs on this isolation level, a query sees only When a transaction runs on this isolation level, a query sees only
data committed before the query began and never sees either dirty data or data committed before the query began and never sees either dirty data or
concurrent transaction changes committed during query execution. concurrent transaction changes committed during query execution.
...@@ -196,7 +204,8 @@ ...@@ -196,7 +204,8 @@
</para> </para>
<para> <para>
Note that the results of execution of SELECT or INSERT (with a query) Note that the results of execution of <command>SELECT</command>
or <command>INSERT</command> (with a query)
statements will not be affected by concurrent transactions. statements will not be affected by concurrent transactions.
</para> </para>
</sect1> </sect1>
...@@ -205,8 +214,9 @@ ...@@ -205,8 +214,9 @@
<title>Serializable Isolation Level</title> <title>Serializable Isolation Level</title>
<para> <para>
This level provides the highest transaction isolation. When a <firstterm>Serializable</firstterm> provides the highest transaction isolation.
transaction is on the <firstterm>serializable</firstterm> level, When a
transaction is on the serializable level,
a query sees only data a query sees only data
committed before the transaction began and never see either dirty data committed before the transaction began and never see either dirty data
or concurrent transaction changes committed during transaction or concurrent transaction changes committed during transaction
...@@ -216,8 +226,9 @@ ...@@ -216,8 +226,9 @@
</para> </para>
<para> <para>
If a row returned by query while executing If a row returned by query while executing a
<command>UPDATE</command>/<command>DELETE</command>/<command>SELECT FOR UPDATE</command> <command>UPDATE</command>
(or <command>DELETE</command> or <command>SELECT FOR UPDATE</command>)
statement is being updated by statement is being updated by
a concurrent uncommitted transaction then the second transaction a concurrent uncommitted transaction then the second transaction
that tries to update this row will wait for the other transaction to that tries to update this row will wait for the other transaction to
...@@ -394,8 +405,8 @@ ERROR: Can't serialize access due to concurrent update ...@@ -394,8 +405,8 @@ ERROR: Can't serialize access due to concurrent update
<note> <note>
<para> <para>
Note that only AccessExclusiveLock blocks <command>SELECT</command> (without FOR Only AccessExclusiveLock blocks <command>SELECT</command> (without
UPDATE) statement. <option>FOR UPDATE</option>) statement.
</para> </para>
</note> </note>
</para> </para>
...@@ -409,11 +420,11 @@ ERROR: Can't serialize access due to concurrent update ...@@ -409,11 +420,11 @@ ERROR: Can't serialize access due to concurrent update
<title>Row-level locks</title> <title>Row-level locks</title>
<para> <para>
These locks are acquired by means of modification of internal These locks are acquired when internal
fields of row being updated/deleted/marked for update. fields of a row are being updated (or deleted or marked for update).
<productname>Postgres</productname> <productname>Postgres</productname>
doesn't remember any information about modified rows in memory and doesn't remember any information about modified rows in memory and
so hasn't limit for locked rows without lock escalation. so has no limit to the number of rows locked without lock escalation.
</para> </para>
<para> <para>
...@@ -434,7 +445,8 @@ ERROR: Can't serialize access due to concurrent update ...@@ -434,7 +445,8 @@ ERROR: Can't serialize access due to concurrent update
<para> <para>
Though <productname>Postgres</productname> Though <productname>Postgres</productname>
provides unblocking read/write access to table provides unblocking read/write access to table
data, it is not the case for all index access methods implemented data, unblocked read/write access is not provided for every
index access methods implemented
in <productname>Postgres</productname>. in <productname>Postgres</productname>.
</para> </para>
...@@ -448,7 +460,7 @@ ERROR: Can't serialize access due to concurrent update ...@@ -448,7 +460,7 @@ ERROR: Can't serialize access due to concurrent update
</term> </term>
<listitem> <listitem>
<para> <para>
Share/exclusive INDEX-level locks are used for read/write access. Share/exclusive index-level locks are used for read/write access.
Locks are released after statement is done. Locks are released after statement is done.
</para> </para>
</listitem> </listitem>
...@@ -460,7 +472,7 @@ ERROR: Can't serialize access due to concurrent update ...@@ -460,7 +472,7 @@ ERROR: Can't serialize access due to concurrent update
</term> </term>
<listitem> <listitem>
<para> <para>
Share/exclusive PAGE-level locks are used for read/write access. Share/exclusive page-level locks are used for read/write access.
Locks are released after page is processed. Locks are released after page is processed.
</para> </para>
...@@ -477,13 +489,13 @@ ERROR: Can't serialize access due to concurrent update ...@@ -477,13 +489,13 @@ ERROR: Can't serialize access due to concurrent update
</term> </term>
<listitem> <listitem>
<para> <para>
Short-term share/exclusive PAGE-level latches are used for Short-term share/exclusive page-level latches are used for
read/write access. Latches are released immediately after the index read/write access. Latches are released immediately after the index
tuple is inserted/fetched. tuple is inserted/fetched.
</para> </para>
<para> <para>
Btree indices provide highest concurrency without deadlock Btree indices provide the highest concurrency without deadlock
conditions. conditions.
</para> </para>
</listitem> </listitem>
...@@ -503,8 +515,8 @@ ERROR: Can't serialize access due to concurrent update ...@@ -503,8 +515,8 @@ ERROR: Can't serialize access due to concurrent update
by <command>SELECT</command> it doesn't mean that this row really by <command>SELECT</command> it doesn't mean that this row really
exists at the time it is returned (i.e. sometime after the exists at the time it is returned (i.e. sometime after the
statement or transaction began) nor statement or transaction began) nor
that the row is protected from deletion/updation by concurrent that the row is protected from deletion or update by concurrent
transactions before the current transaction commit or rollback. transactions before the current transaction does a commit or rollback.
</para> </para>
<para> <para>
......
<sect1> <sect1>
<title>Terminology</title> <title>Terminology</title>
<para> <para>
In the following documentation, In the following documentation,
<firstterm>site</firstterm> <firstterm>site</firstterm>
may be interpreted as the host machine on which may be interpreted as the host machine on which
<Productname>Postgres</Productname> is installed. <Productname>Postgres</Productname> is installed.
Since it is possible to install more than one set of Since it is possible to install more than one set of
<Productname>Postgres</Productname> <Productname>Postgres</Productname>
databases on a single host, this term more precisely denotes any databases on a single host, this term more precisely denotes any
particular set of installed particular set of installed
<Productname>Postgres</Productname> binaries and databases. <Productname>Postgres</Productname> binaries and databases.
</para> </para>
<para> <para>
The The
<Productname>Postgres</Productname> <firstterm>superuser</firstterm> <Productname>Postgres</Productname> <firstterm>superuser</firstterm>
is the user named <replaceable>postgres</replaceable> is the user named <replaceable>postgres</replaceable>
who owns the <Productname>Postgres</Productname> who owns the <Productname>Postgres</Productname>
binaries and database files. As the database superuser, all binaries and database files. As the database superuser, all
protection mechanisms may be bypassed and any data accessed protection mechanisms may be bypassed and any data accessed
arbitrarily. arbitrarily.
In addition, the <Productname>Postgres</Productname> superuser is allowed to execute In addition, the <Productname>Postgres</Productname> superuser is allowed to execute
some support programs which are generally not available to all users. some support programs which are generally not available to all users.
Note that the <Productname>Postgres</Productname> superuser is Note that the <Productname>Postgres</Productname> superuser is
<emphasis>not</emphasis> <emphasis>not</emphasis>
the same as the Unix superuser (which will be referred to as <firstterm>root</firstterm>). the same as the Unix superuser (which will be referred to as <firstterm>root</firstterm>).
The superuser should have a non-zero user identifier (<firstterm>UID</firstterm>) The superuser should have a non-zero user identifier (<firstterm>UID</firstterm>)
for security reasons. for security reasons.
</para> </para>
<para> <para>
The The
<firstterm>database administrator</firstterm> <firstterm>database administrator</firstterm>
or <acronym>DBA</acronym>, is the person who is responsible for installing or <acronym>DBA</acronym>, is the person who is responsible for installing
<Productname>Postgres</Productname> with mechanisms to <Productname>Postgres</Productname> with mechanisms to
enforce a security policy for a site. The DBA can add new users by enforce a security policy for a site. The DBA can add new users by
the method described below the method described below
and maintain a set of template databases for use by and maintain a set of template databases for use by
<application>createdb</application>. <application>createdb</application>.
</para> </para>
<para> <para>
The <application>postmaster</application> The <application>postmaster</application>
is the process that acts as a clearing-house for requests is the process that acts as a clearing-house for requests
to the <Productname>Postgres</Productname> system. to the <Productname>Postgres</Productname> system.
Frontend applications connect to the <application>postmaster</application>, Frontend applications connect to the <application>postmaster</application>,
which keeps tracks of any system errors and communication between the which keeps tracks of any system errors and communication between the
backend processes. The <application>postmaster</application> backend processes. The <application>postmaster</application>
can take several command-line arguments to tune its behavior. can take several command-line arguments to tune its behavior.
However, supplying arguments is necessary only if you intend to run multiple However, supplying arguments is necessary only if you intend to run multiple
sites or a non-default site. sites or a non-default site.
</para> </para>
<para> <para>
The <Productname>Postgres</Productname> backend The <Productname>Postgres</Productname> backend
(the actual executable program <application>postgres</application>) may be executed (the actual executable program <application>postgres</application>) may be executed
directly from the user shell by the directly from the user shell by the
<Productname>Postgres</Productname> super-user <Productname>Postgres</Productname> super-user
(with the database name as an argument). However, (with the database name as an argument). However,
doing this bypasses the shared buffer pool and lock table associated doing this bypasses the shared buffer pool and lock table associated
with a postmaster/site, therefore this is not recommended in a multiuser with a postmaster/site, therefore this is not recommended in a multiuser
site. site.
</para> </para>
</sect1> </sect1>
<sect1> <sect1>
<title>Notation</title> <title>Notation</title>
<para> <para>
<quote>...</quote> or <filename>/usr/local/pgsql/</filename> <quote>...</quote> or <filename>/usr/local/pgsql/</filename>
at the front of a file name is used to represent the at the front of a file name is used to represent the
path to the <Productname>Postgres</Productname> superuser's home directory. path to the <Productname>Postgres</Productname> superuser's home directory.
</para> </para>
<para> <para>
In a command synopsis, brackets In a command synopsis, brackets
(<quote>[</quote> and <quote>]</quote>) indicate an optional phrase or keyword. (<quote>[</quote> and <quote>]</quote>) indicate an optional phrase or keyword.
Anything in braces Anything in braces
(<quote>{</quote> and <quote>}</quote>) and containing vertical bars (<quote>|</quote>) (<quote>{</quote> and <quote>}</quote>) and containing vertical bars (<quote>|</quote>)
indicates that you must choose one. indicates that you must choose one.
</para> </para>
<para> <para>
In examples, parentheses (<quote>(</quote> and <quote>)</quote>) are used to group boolean In examples, parentheses (<quote>(</quote> and <quote>)</quote>) are used to group boolean
expressions. <quote>|</quote> is the boolean operator OR. expressions. <quote>|</quote> is the boolean operator OR.
</para> </para>
<para> <para>
Examples will show commands executed from various accounts and programs. Examples will show commands executed from various accounts and programs.
Commands executed from the root account will be preceeded with <quote>&gt;</quote>. Commands executed from the root account will be preceeded with <quote>&gt;</quote>.
Commands executed from the <Productname>Postgres</Productname> Commands executed from the <Productname>Postgres</Productname>
superuser account will be preceeded with <quote>%</quote>, while commands superuser account will be preceeded with <quote>%</quote>, while commands
executed from an unprivileged user's account will be preceeded with executed from an unprivileged user's account will be preceeded with
<quote>$</quote>. <quote>$</quote>.
<acronym>SQL</acronym> commands will be preceeded with <quote>=&gt;</quote> <acronym>SQL</acronym> commands will be preceeded with <quote>=&gt;</quote>
or will have no leading prompt, depending on the context. or will have no leading prompt, depending on the context.
</para> </para>
<note> <note>
<para> <para>
At the time of writing (<Productname>Postgres</Productname> v6.4) the notation for At the time of writing (<Productname>Postgres</Productname> v6.5) the notation for
flagging commands is not universally consistant throughout the documentation set. flagging commands is not universally consistant throughout the documentation set.
Please report problems to Please report problems to
<ulink url="mailto:docs@postgresql.org">the Documentation Mailing List</ulink>. <ulink url="mailto:docs@postgresql.org">the Documentation Mailing List</ulink>.
</para> </para>
</note> </note>
</sect1> </sect1>
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$Header: /cvsroot/pgsql/doc/src/sgml/postgres.sgml,v 1.24 1999/05/26 17:30:29 thomas Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/postgres.sgml,v 1.25 1999/05/27 15:49:08 thomas Exp $
Postgres integrated documentation. Postgres integrated documentation.
Other subset docs should be copied and shrunk from here. Other subset docs should be copied and shrunk from here.
thomas 1998-02-23 thomas 1998-02-23
$Log: postgres.sgml,v $ $Log: postgres.sgml,v $
Revision 1.25 1999/05/27 15:49:08 thomas
Markup fixes.
Update for v6.5 release.
Revision 1.24 1999/05/26 17:30:29 thomas Revision 1.24 1999/05/26 17:30:29 thomas
Add chapters on CVS access, MVCC, SQL theory to the docs. Add chapters on CVS access, MVCC, SQL theory to the docs.
Add an appendix with more details on date/time attributes and handling. Add an appendix with more details on date/time attributes and handling.
...@@ -126,6 +130,7 @@ Move SQL reference pages up into the User's Guide. ...@@ -126,6 +130,7 @@ Move SQL reference pages up into the User's Guide.
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...@@ -291,6 +296,7 @@ Your name here... ...@@ -291,6 +296,7 @@ Your name here...
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<sect1> <sect1 id="y2k">
<title>Y2K Statement</title> <title>Y2K Statement</title>
<note> <note>
<title>Author</title> <title>Author</title>
<para> <para>
Written by Written by
<ulink url="mailto:lockhart@alumni.caltech.edu">Thomas Lockhart</ulink> <ulink url="mailto:lockhart@alumni.caltech.edu">Thomas Lockhart</ulink>
on 1998-10-22. on 1998-10-22.
</para> </para>
</note> </note>
<para> <para>
The <productname>PostgreSQL</productname> Global Development Team provides The <productname>PostgreSQL</productname> Global Development Team provides
the <productname>Postgres</productname> software code tree as a public service, the <productname>Postgres</productname> software code tree as a public service,
without warranty and without liability for it's behavior or performance. without warranty and without liability for it's behavior or performance.
However, at the time of writing: However, at the time of writing:
</para> </para>
<itemizedlist> <itemizedlist>
<listitem> <listitem>
<para> <para>
The author of this statement, a volunteer on the <productname>Postgres</productname> The author of this statement, a volunteer on the <productname>Postgres</productname>
support team since November, 1996, is not aware of support team since November, 1996, is not aware of
any problems in the <productname>Postgres</productname> code base related any problems in the <productname>Postgres</productname> code base related
to time transitions around Jan 1, 2000 (Y2K). to time transitions around Jan 1, 2000 (Y2K).
</para> </para>
</listitem> </listitem>
<listitem> <listitem>
<para> <para>
The author of this statement is not aware of any reports of Y2K problems The author of this statement is not aware of any reports of Y2K problems
uncovered in regression testing uncovered in regression testing
or in other field use of recent or current versions or in other field use of recent or current versions
of <productname>Postgres</productname>. We might have expected of <productname>Postgres</productname>. We might have expected
to hear about problems if they existed, given the installed base and to hear about problems if they existed, given the installed base and
the active participation of users on the support mailing lists. the active participation of users on the support mailing lists.
</para> </para>
</listitem> </listitem>
<listitem> <listitem>
<para> <para>
To the best of the author's knowledge, the To the best of the author's knowledge, the
assumptions Postgres makes about dates specified with a two-digit year assumptions Postgres makes about dates specified with a two-digit year
are documented in the current are documented in the current
<ulink url="http://www.postgresql.org/docs/user/datatype.htm">User's Guide</ulink> <ulink url="http://www.postgresql.org/docs/user/datatype.htm">User's Guide</ulink>
in the chapter on data types. in the chapter on data types.
For two-digit years, the significant transition year is 1970, not 2000; For two-digit years, the significant transition year is 1970, not 2000;
e.g. <quote>70-01-01</quote> is interpreted as <quote>1970-01-01</quote>, e.g. <quote>70-01-01</quote> is interpreted as <quote>1970-01-01</quote>,
whereas <quote>69-01-01</quote> is interpreted as <quote>2069-01-01</quote>. whereas <quote>69-01-01</quote> is interpreted as <quote>2069-01-01</quote>.
</para> </para>
</listitem> </listitem>
<listitem> <listitem>
<para> <para>
Any Y2K problems in the underlying OS related to obtaining "the Any Y2K problems in the underlying OS related to obtaining "the
current time" may propagate into apparent Y2K problems in current time" may propagate into apparent Y2K problems in
<productname>Postgres</productname>. <productname>Postgres</productname>.
</para> </para>
</listitem> </listitem>
</itemizedlist>
</itemizedlist> <para>
Refer to
<para> <ulink url="http://www.gnu.org/software/year2000.html">The Gnu Project</ulink>
Refer to and
<ulink url="http://www.gnu.org/software/year2000.html">The Gnu Project</ulink> <ulink url="http://language.perl.com/news/y2k.html">The Perl Institute</ulink>
and for further discussion of Y2K issues, particularly
<ulink url="http://language.perl.com/news/y2k.html">The Perl Institute</ulink> as it relates to open source, no fee software.
for further discussion of Y2K issues, particularly </para>
as it relates to open source, no fee software.
</para>
</sect1> </sect1>
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