mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-10-07 04:16:53 +02:00
Document effect of constant folding on CASE.
Back-patch to all supported versions. Laurenz Albe
This commit is contained in:
parent
dc22b34f86
commit
40265e3446
@ -10563,6 +10563,16 @@ 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">
|
||||
|
Loading…
Reference in New Issue
Block a user