Re: 7.2 crash... - Mailing list pgsql-bugs

Here is a patch with a fix outlined by Tom:

    test=> CREATE OR REPLACE FUNCTION runMaintenance()
    test-> RETURNS BOOL AS '
    test'>   VACUUM;
    test'>   SELECT TRUE;
    test'> ' LANGUAGE sql;
    CREATE
    test=>
    test=> select runMaintenance();
    ERROR:  VACUUM cannot be executed from a function

Looks good.  Will commit after typical delay.

---------------------------------------------------------------------------

Tom Lane wrote:
> "Rod Taylor" <rbt@zort.ca> writes:
> > 7.2 crashes with the below function:
> > CREATE OR REPLACE FUNCTION runMaintenance()
> > RETURNS BOOL AS '
> >   VACUUM;
> >   SELECT TRUE;
> > ' LANGUAGE sql;
>
> AFAICS there is no way that we can support VACUUM inside a function;
> the forced transaction commits that VACUUM performs will recycle any
> memory allocated by the function executor, leading to death and
> destruction upon return from VACUUM.
>
> Accordingly, what we really need is a way of preventing VACUUM from
> executing in the above scenario.  The IsTransactionBlock() test it
> already has isn't sufficient.
>
> I have thought of something that probably would be sufficient:
>
>     if (!MemoryContextContains(QueryContext, vacstmt))
>         elog(ERROR, "VACUUM cannot be executed from a function");
>
> This is truly, horribly ugly ... but it'd get the job done, because only
> interactive queries will generate parsetrees in QueryContext.
>
> Can someone think of a better way?
>
>             regards, tom lane
>
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Index: src/backend/commands/vacuum.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/commands/vacuum.c,v
retrieving revision 1.223
diff -c -r1.223 vacuum.c
*** src/backend/commands/vacuum.c    12 Apr 2002 20:38:25 -0000    1.223
--- src/backend/commands/vacuum.c    14 Apr 2002 16:41:37 -0000
***************
*** 181,186 ****
--- 181,189 ----
      if (IsTransactionBlock())
          elog(ERROR, "%s cannot run inside a BEGIN/END block", stmttype);

+     if (!MemoryContextContains(QueryContext, vacstmt))
+         elog(ERROR, "VACUUM cannot be executed from a function");
+
      /*
       * Send info about dead objects to the statistics collector
       */