Document PERFORM limitation when using WITH queries.

Backpatch to 9.0 and 9.1.

Report from depstein@alliedtesting.com.
This commit is contained in:
Bruce Momjian 2011-09-06 13:41:32 -04:00
parent 0154332951
commit dcc728eef4

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@ -845,6 +845,9 @@ PERFORM <replaceable>query</replaceable>;
result. Write the <replaceable>query</replaceable> the same result. Write the <replaceable>query</replaceable> the same
way you would write an SQL <command>SELECT</> command, but replace the way you would write an SQL <command>SELECT</> command, but replace the
initial keyword <command>SELECT</> with <command>PERFORM</command>. initial keyword <command>SELECT</> with <command>PERFORM</command>.
For <keyword>WITH</> queries, use <keyword>PERFORM</> and then
place the query in parentheses. (In this case, the query can only
return one row.)
<application>PL/pgSQL</application> variables will be <application>PL/pgSQL</application> variables will be
substituted into the query just as for commands that return no result, substituted into the query just as for commands that return no result,
and the plan is cached in the same way. Also, the special variable and the plan is cached in the same way. Also, the special variable