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Describe the behavior of the SQL_ASCII encoding more accurately.

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This commit is contained in:
Tom Lane 2005-10-13 21:43:43 +00:00
parent 6f9cb4eb43
commit a9980ec37b
1 changed files with 28 additions and 8 deletions
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36
doc/src/sgml/charset.sgml
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@ -1,4 +1,4 @@
<!-- $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"> <chapter id="charset">
<title>Localization</> <title>Localization</>
@ -517,8 +517,8 @@ initdb --locale=sv_SE
</row> </row>
<row> <row>
<entry><literal>SQL_ASCII</literal></entry> <entry><literal>SQL_ASCII</literal></entry>
<entry><acronym>ASCII</acronym></entry> <entry>unspecified (see text)</entry>
<entry>English</entry> <entry><emphasis>any</></entry>
<entry>1</entry> <entry>1</entry>
<entry></entry> <entry></entry>
</row> </row>
@ -533,7 +533,7 @@ initdb --locale=sv_SE
<entry><literal>UTF8</literal></entry> <entry><literal>UTF8</literal></entry>
<entry>Unicode, 8-bit</entry> <entry>Unicode, 8-bit</entry>
<entry><emphasis>all</></entry> <entry><emphasis>all</></entry>
<entry>1-3</entry> <entry>1-4</entry>
<entry><literal>Unicode</></entry> <entry><literal>Unicode</></entry>
</row> </row>
<row> <row>
@ -595,6 +595,21 @@ initdb --locale=sv_SE
JDBC driver does not support <literal>MULE_INTERNAL</>, <literal>LATIN6</>, JDBC driver does not support <literal>MULE_INTERNAL</>, <literal>LATIN6</>,
<literal>LATIN8</>, and <literal>LATIN10</>. <literal>LATIN8</>, and <literal>LATIN10</>.
</para> </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>
<sect2> <sect2>
@ -884,9 +899,7 @@ $ <userinput>psql -l</userinput>
</row> </row>
<row> <row>
<entry><literal>SQL_ASCII</literal></entry> <entry><literal>SQL_ASCII</literal></entry>
<entry><emphasis>SQL_ASCII</emphasis>, <entry><emphasis>any (no conversion will be performed)</emphasis>
<literal>MULE_INTERNAL</literal>,
<literal>UTF8</literal>
</entry> </entry>
</row> </row>
<row> <row>
@ -956,7 +969,7 @@ $ <userinput>psql -l</userinput>
</table> </table>
<para> <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 tell <productname>PostgreSQL</productname> the character set
(encoding) you would like to use in the client. There are several (encoding) you would like to use in the client. There are several
ways to accomplish this: ways to accomplish this:
@ -1070,6 +1083,13 @@ RESET client_encoding;
hexadecimal byte values in parentheses, e.g., hexadecimal byte values in parentheses, e.g.,
<literal>(826C)</literal>. <literal>(826C)</literal>.
</para> </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>
<sect2> <sect2>