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| author | Noah Misch <noah@leadboat.com> | 2013-06-26 19:51:56 -0400 |
|---|---|---|
| committer | Noah Misch <noah@leadboat.com> | 2013-06-26 20:33:47 -0400 |
| commit | 8356d9498860cd377eb1edd8b64a840b6b411081 (patch) | |
| tree | abc2d6d27332359ad4ae32173c8c9ecec6123e46 | |
| parent | 1c6afc40f7f9e3fd823e415adbfa6b2ac6f9864d (diff) | |
Document effect of constant folding on CASE.
Back-patch to all supported versions.
Laurenz Albe
| -rw-r--r-- | doc/src/sgml/func.sgml | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index d295ec25210..bbd6605c993 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -9981,6 +9981,16 @@ SELECT a, SELECT ... WHERE CASE WHEN x <> 0 THEN y/x > 1.5 ELSE false END; </programlisting> </para> + + <note> + <para> + As described in <xref linkend="xfunc-volatility">, functions and + operators marked <literal>IMMUTABLE</literal> can be evaluated when + the query is planned rather than when it is executed. This means + that constant parts of a subexpression that is not evaluated during + query execution might still be evaluated during query planning. + </para> + </note> </sect2> <sect2 id="functions-coalesce-nvl-ifnull"> |