Do a conditional SPI_push/SPI_pop when replanning a query in

RevalidateCachedPlan.  This is to avoid a "SPI_ERROR_CONNECT" failure when
the planner calls a SPI-using function and we are already inside one.
The alternative fix is to expect callers of RevalidateCachedPlan to do this,
which seems likely to result in additional hard-to-detect bugs of omission.
Per reports from Frank van Vugt and Marek Lewczuk.

Back-patch to 8.3. It's much harder to trigger the bug in 8.3, due to a
smaller set of cases in which plans can be invalidated, but it could happen.
(I think perhaps only a SI reset event could make 8.3 fail here, but that's
certainly within the realm of possibility.)

diff --git a/src/backend/utils/cache/plancache.c b/src/backend/utils/cache/plancache.c
index 5019df6f86a91472b9ec117b47ff6926a77a6a0d..1742fa618c3e6c9cb55a193a1c0511cc2fa5b339 100644 (file)
--- a/src/backend/utils/cache/plancache.c
+++ b/src/backend/utils/cache/plancache.c
@@ -33,7 +33,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/cache/plancache.c,v 1.15.2.2 2008/12/13 02:00:29 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/cache/plancache.c,v 1.15.2.3 2009/07/14 15:38:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -43,6 +43,7 @@
 #include "access/transam.h"
 #include "catalog/namespace.h"
 #include "executor/executor.h"
+#include "executor/spi.h"
 #include "optimizer/clauses.h"
 #include "storage/lmgr.h"
 #include "tcop/pquery.h"
@@ -500,9 +501,22 @@ RevalidateCachedPlan(CachedPlanSource *plansource, bool useResOwner)
 
                        if (plansource->fully_planned)
                        {
-                               /* Generate plans for queries */
+                               /*
+                                * Generate plans for queries.
+                                *
+                                * The planner may try to call SPI-using functions, which
+                                * causes a problem if we're already inside one.  Rather than
+                                * expect all SPI-using code to do SPI_push whenever a replan
+                                * could happen, it seems best to take care of the case here.
+                                */
+                               bool    pushed;
+
+                               pushed = SPI_push_conditional();
+
                                slist = pg_plan_queries(slist, plansource->cursor_options,
                                                                                NULL, false);
+
+                               SPI_pop_conditional(pushed);
                        }
 
                        /*