Fix things so that array_agg_finalfn does not modify or free its input

ArrayBuildState, per trouble report from Merlin Moncure.  By adopting
this fix, we are essentially deciding that aggregate final-functions
should not modify their inputs ever.  Adjust documentation and comments
to match that conclusion.

1 files changed, 6 insertions, 3 deletions

diff --git a/src/backend/utils/adt/array_userfuncs.c b/src/backend/utils/adt/array_userfuncs.c
index c30d6b42b07..a1f48d8784c 100644
--- a/src/backend/utils/adt/array_userfuncs.c
+++ b/src/backend/utils/adt/array_userfuncs.c
@@ -6,7 +6,7 @@
  * Copyright (c) 2003-2009, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/array_userfuncs.c,v 1.30 2009/06/11 14:49:03 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/array_userfuncs.c,v 1.31 2009/06/20 18:45:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -537,10 +537,13 @@ array_agg_finalfn(PG_FUNCTION_ARGS)
 	dims[0] = state->nelems;
 	lbs[0] = 1;
 
-	/* Release working state if regular aggregate, but not if window agg */
+	/*
+	 * Make the result.  We cannot release the ArrayBuildState because
+	 * sometimes aggregate final functions are re-executed.
+	 */
 	result = makeMdArrayResult(state, 1, dims, lbs,
 							   CurrentMemoryContext,
-							   IsA(fcinfo->context, AggState));
+							   false);
 
 	PG_RETURN_DATUM(result);
 }