Commit a9980ec3 authored by Tom Lane's avatar Tom Lane

Describe the behavior of the SQL_ASCII encoding more accurately.

parent 6f9cb4eb
<!-- $PostgreSQL: pgsql/doc/src/sgml/charset.sgml,v 2.73 2005/06/21 04:02:29 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/charset.sgml,v 2.74 2005/10/13 21:43:43 tgl Exp $ -->
<chapter id="charset">
<title>Localization</>
......@@ -517,8 +517,8 @@ initdb --locale=sv_SE
</row>
<row>
<entry><literal>SQL_ASCII</literal></entry>
<entry><acronym>ASCII</acronym></entry>
<entry>English</entry>
<entry>unspecified (see text)</entry>
<entry><emphasis>any</></entry>
<entry>1</entry>
<entry></entry>
</row>
......@@ -533,7 +533,7 @@ initdb --locale=sv_SE
<entry><literal>UTF8</literal></entry>
<entry>Unicode, 8-bit</entry>
<entry><emphasis>all</></entry>
<entry>1-3</entry>
<entry>1-4</entry>
<entry><literal>Unicode</></entry>
</row>
<row>
......@@ -595,6 +595,21 @@ initdb --locale=sv_SE
JDBC driver does not support <literal>MULE_INTERNAL</>, <literal>LATIN6</>,
<literal>LATIN8</>, and <literal>LATIN10</>.
</para>
<para>
The <literal>SQL_ASCII</> setting behaves considerably differently
from the other settings. When the server character set is
<literal>SQL_ASCII</>, the server interprets byte values 0-127
according to the ASCII standard, while byte values 128-255 are taken
as uninterpreted characters. No encoding conversion will be done when
the setting is <literal>SQL_ASCII</>. Thus, this setting is not so
much a declaration that a specific encoding is in use, as a declaration
of ignorance about the encoding. In most cases, if you are
working with any non-ASCII data, it is unwise to use the
<literal>SQL_ASCII</> setting, because
<productname>PostgreSQL</productname> will be unable to help you by
converting or validating non-ASCII characters.
</para>
</sect2>
<sect2>
......@@ -884,9 +899,7 @@ $ <userinput>psql -l</userinput>
</row>
<row>
<entry><literal>SQL_ASCII</literal></entry>
<entry><emphasis>SQL_ASCII</emphasis>,
<literal>MULE_INTERNAL</literal>,
<literal>UTF8</literal>
<entry><emphasis>any (no conversion will be performed)</emphasis>
</entry>
</row>
<row>
......@@ -956,7 +969,7 @@ $ <userinput>psql -l</userinput>
</table>
<para>
To enable the automatic character set conversion, you have to
To enable automatic character set conversion, you have to
tell <productname>PostgreSQL</productname> the character set
(encoding) you would like to use in the client. There are several
ways to accomplish this:
......@@ -1070,6 +1083,13 @@ RESET client_encoding;
hexadecimal byte values in parentheses, e.g.,
<literal>(826C)</literal>.
</para>
<para>
If the client character set is defined as <literal>SQL_ASCII</>,
encoding conversion is disabled, regardless of the server's character
set. Just as for the server, use of <literal>SQL_ASCII</> is unwise
unless you are working with all-ASCII data.
</para>
</sect2>
<sect2>
......
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