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Clean up description of 9.0's incompatible changes in SIMILAR TO and

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SQL-style substring().
This commit is contained in:
Tom Lane 2010-04-05 02:46:42 +00:00
parent ce36151ac7
commit 87d5c22925
1 changed files with 24 additions and 37 deletions
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doc/src/sgml/release-9.0.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/release-9.0.sgml,v 2.14 2010/04/03 07:22:55 petere Exp $ --> <!-- $PostgreSQL: pgsql/doc/src/sgml/release-9.0.sgml,v 2.15 2010/04/05 02:46:42 tgl Exp $ -->
<sect1 id="release-9-0"> <sect1 id="release-9-0">
@ -97,43 +97,30 @@
<listitem> <listitem>
<para> <para>
Fix <link linkend="functions-similarto-regexp"><literal>SIMILAR Improve standards compliance of <link
TO</></link> to match the SQL standard-specified behavior linkend="functions-similarto-regexp"><literal>SIMILAR TO</></link>
by processing <literal>?</> and <literal>{}</> the same way patterns and SQL-style <function>substring()</> patterns (Tom Lane)
they are processed in regular expressions (Tom Lane) </para>
<para>
This includes treating <literal>?</> and <literal>{...}</> as
pattern metacharacters, while they were simple literal characters
before; that corresponds to new features added in SQL:2008.
Also, <literal>^</> and <literal>$</> are now treated as simple
literal characters; formerly they were treated as metacharacters,
as if the pattern were following POSIX rather than SQL rules.
Also, in SQL-standard <function>substring()</>, use of parentheses
for nesting no longer interferes with capturing of a substring.
Also, processing of bracket expressions (character classes) is
now more standards-compliant.
</para> </para>
</listitem> </listitem>
<listitem> <listitem>
<para> <para>
Properly treat <literal>^</> and <literal>$</> as literals in Reject negative length values in 3-parameter <link
<literal>SIMILAR TO</> patterns, to match the SQL standard (Tom Lane) linkend="functions-string-sql"><function>substring()</></link>
</para> for bit strings, per the SQL standard (Tom Lane)
<para>
Previously these were treated using regular expression syntax. This
change breaks backward compatibility. This also affects
<function>substring()</>'s interpretation of regular expressions.
</para>
</listitem>
<listitem>
<para>
Process parentheses as literals in <literal>SIMILAR TO</> expressions;
also make character class handling more standards-compliant (Tom Lane)
</para>
<para>
This also affects <function>substring()</>'s handling of regular
expressions.
</para>
</listitem>
<listitem>
<para>
Do not allow <link
linkend="functions-string-sql"><function>substring()</></link>
to have a negative third length, per the SQL standard (Tom Lane)
</para> </para>
</listitem> </listitem>