Previous fix for temporary file management broke returning a set from

PL/pgSQL function within an exception handler. Make sure we use the right
resource owner when we create the tuplestore to hold returned tuples.

Simplify tuplestore API so that the caller doesn't need to be in the right
memory context when calling tuplestore_put* functions. tuplestore.c
automatically switches to the memory context used when the tuplestore was
created. Tuplesort was already modified like this earlier. This patch also
removes the now useless MemoryContextSwitch calls from callers.

Report by Aleksei on pgsql-bugs on Dec 22 2009. Backpatch to 8.1, like
the previous patch that broke this.

4 files changed, 7 insertions, 44 deletions

diff --git a/contrib/dblink/dblink.c b/contrib/dblink/dblink.c
index 61585644f92..d3875529fd0 100644
--- a/contrib/dblink/dblink.c
+++ b/contrib/dblink/dblink.c
@@ -8,7 +8,7 @@
  * Darko Prenosil <Darko.Prenosil@finteh.hr>
  * Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
  *
- * $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.84 2009/09/12 23:20:52 joe Exp $
+ * $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.85 2009/12/29 17:40:59 heikki Exp $
  * Copyright (c) 2001-2009, PostgreSQL Global Development Group
  * ALL RIGHTS RESERVED;
  *
@@ -1703,10 +1703,7 @@ dblink_get_notify(PG_FUNCTION_ARGS)
 		else
 			nulls[2] = true;
 
-		/* switch to appropriate context while storing the tuple */
-		MemoryContextSwitchTo(per_query_ctx);
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
-		MemoryContextSwitchTo(oldcontext);
 
 		PQfreemem(notify);
 		PQconsumeInput(conn);
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index e2b3afa4b6f..69125430230 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -14,7 +14,7 @@
  * Copyright (c) 2008-2009, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/contrib/pg_stat_statements/pg_stat_statements.c,v 1.9 2009/12/15 20:04:49 tgl Exp $
+ *	  $PostgreSQL: pgsql/contrib/pg_stat_statements/pg_stat_statements.c,v 1.10 2009/12/29 17:40:59 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -783,6 +783,8 @@ pg_stat_statements(PG_FUNCTION_ARGS)
 	rsinfo->setResult = tupstore;
 	rsinfo->setDesc = tupdesc;
 
+	MemoryContextSwitchTo(oldcontext);
+
 	LWLockAcquire(pgss->lock, LW_SHARED);
 
 	hash_seq_init(&hash_seq, pgss_hash);
@@ -793,9 +795,6 @@ pg_stat_statements(PG_FUNCTION_ARGS)
 		int			i = 0;
 		Counters	tmp;
 
-		/* generate junk in short-term context */
-		MemoryContextSwitchTo(oldcontext);
-
 		memset(values, 0, sizeof(values));
 		memset(nulls, 0, sizeof(nulls));
 
@@ -833,8 +832,6 @@ pg_stat_statements(PG_FUNCTION_ARGS)
 
 		Assert(i == PG_STAT_STATEMENTS_COLS);
 
-		/* switch to appropriate context while storing the tuple */
-		MemoryContextSwitchTo(per_query_ctx);
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
 	}
 
@@ -843,8 +840,6 @@ pg_stat_statements(PG_FUNCTION_ARGS)
 	/* clean up and return the tuplestore */
 	tuplestore_donestoring(tupstore);
 
-	MemoryContextSwitchTo(oldcontext);
-
 	return (Datum) 0;
 }
 
diff --git a/contrib/tablefunc/tablefunc.c b/contrib/tablefunc/tablefunc.c
index 48512bd9349..272b1b43777 100644
--- a/contrib/tablefunc/tablefunc.c
+++ b/contrib/tablefunc/tablefunc.c
@@ -1,5 +1,5 @@
 /*
- * $PostgreSQL: pgsql/contrib/tablefunc/tablefunc.c,v 1.60 2009/06/11 14:48:52 momjian Exp $
+ * $PostgreSQL: pgsql/contrib/tablefunc/tablefunc.c,v 1.61 2009/12/29 17:40:59 heikki Exp $
  *
  *
  * tablefunc
@@ -567,14 +567,9 @@ crosstab(PG_FUNCTION_ARGS)
 		{
 			HeapTuple	tuple;
 
-			/* build the tuple */
+			/* build the tuple and store it */
 			tuple = BuildTupleFromCStrings(attinmeta, values);
-
-			/* switch to appropriate context while storing the tuple */
-			oldcontext = MemoryContextSwitchTo(per_query_ctx);
 			tuplestore_puttuple(tupstore, tuple);
-			MemoryContextSwitchTo(oldcontext);
-
 			heap_freetuple(tuple);
 		}
 
@@ -807,7 +802,6 @@ get_crosstab_tuplestore(char *sql,
 	HeapTuple	tuple;
 	int			ret;
 	int			proc;
-	MemoryContext SPIcontext;
 
 	/* initialize our tuplestore (while still in query context!) */
 	tupstore = tuplestore_begin_heap(randomAccess, false, work_mem);
@@ -907,10 +901,7 @@ get_crosstab_tuplestore(char *sql,
 					/* rowid changed, flush the previous output row */
 					tuple = BuildTupleFromCStrings(attinmeta, values);
 
-					/* switch to appropriate context while storing the tuple */
-					SPIcontext = MemoryContextSwitchTo(per_query_ctx);
 					tuplestore_puttuple(tupstore, tuple);
-					MemoryContextSwitchTo(SPIcontext);
 
 					for (j = 0; j < result_ncols; j++)
 						xpfree(values[j]);
@@ -943,10 +934,7 @@ get_crosstab_tuplestore(char *sql,
 		/* flush the last output row */
 		tuple = BuildTupleFromCStrings(attinmeta, values);
 
-		/* switch to appropriate context while storing the tuple */
-		SPIcontext = MemoryContextSwitchTo(per_query_ctx);
 		tuplestore_puttuple(tupstore, tuple);
-		MemoryContextSwitchTo(SPIcontext);
 	}
 
 	if (SPI_finish() != SPI_OK_FINISH)
@@ -1232,7 +1220,6 @@ build_tuplestore_recursively(char *key_fld,
 							 Tuplestorestate *tupstore)
 {
 	TupleDesc	tupdesc = attinmeta->tupdesc;
-	MemoryContext oldcontext;
 	int			ret;
 	int			proc;
 	int			serial_column;
@@ -1310,15 +1297,9 @@ build_tuplestore_recursively(char *key_fld,
 		/* construct the tuple */
 		tuple = BuildTupleFromCStrings(attinmeta, values);
 
-		/* switch to long lived context while storing the tuple */
-		oldcontext = MemoryContextSwitchTo(per_query_ctx);
-
 		/* now store it */
 		tuplestore_puttuple(tupstore, tuple);
 
-		/* now reset the context */
-		MemoryContextSwitchTo(oldcontext);
-
 		/* increment level */
 		level++;
 	}
@@ -1404,15 +1385,9 @@ build_tuplestore_recursively(char *key_fld,
 			xpfree(current_key);
 			xpfree(current_key_parent);
 
-			/* switch to long lived context while storing the tuple */
-			oldcontext = MemoryContextSwitchTo(per_query_ctx);
-
 			/* store the tuple for later use */
 			tuplestore_puttuple(tupstore, tuple);
 
-			/* now reset the context */
-			MemoryContextSwitchTo(oldcontext);
-
 			heap_freetuple(tuple);
 
 			/* recurse using current_key_parent as the new start_with */
diff --git a/contrib/xml2/xpath.c b/contrib/xml2/xpath.c
index 203e53905be..a003dd00c82 100644
--- a/contrib/xml2/xpath.c
+++ b/contrib/xml2/xpath.c
@@ -1,5 +1,5 @@
 /*
- * $PostgreSQL: pgsql/contrib/xml2/xpath.c,v 1.23 2009/06/11 14:48:53 momjian Exp $
+ * $PostgreSQL: pgsql/contrib/xml2/xpath.c,v 1.24 2009/12/29 17:40:59 heikki Exp $
  *
  * Parser interface for DOM-based parser (libxml) rather than
  * stream-based SAX-type parser
@@ -821,9 +821,7 @@ xpath_table(PG_FUNCTION_ARGS)
 		{
 			/* not well-formed, so output all-NULL tuple */
 			ret_tuple = BuildTupleFromCStrings(attinmeta, values);
-			oldcontext = MemoryContextSwitchTo(per_query_ctx);
 			tuplestore_puttuple(tupstore, ret_tuple);
-			MemoryContextSwitchTo(oldcontext);
 			heap_freetuple(ret_tuple);
 		}
 		else
@@ -897,9 +895,7 @@ xpath_table(PG_FUNCTION_ARGS)
 				if (had_values)
 				{
 					ret_tuple = BuildTupleFromCStrings(attinmeta, values);
-					oldcontext = MemoryContextSwitchTo(per_query_ctx);
 					tuplestore_puttuple(tupstore, ret_tuple);
-					MemoryContextSwitchTo(oldcontext);
 					heap_freetuple(ret_tuple);
 				}