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 437b7d1114ee9f700b2fa5739f1a1591cfdb5ae5..82f90a93126d22f175d82643118e89cc7f156fb6 100644 (file)
--- a/src/backend/utils/cache/plancache.c
+++ b/src/backend/utils/cache/plancache.c
@@ -35,7 +35,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/cache/plancache.c,v 1.27 2009/06/11 14:49:05 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/cache/plancache.c,v 1.28 2009/07/14 15:37:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -45,6 +45,7 @@
 #include "access/transam.h"
 #include "catalog/namespace.h"
 #include "executor/executor.h"
+#include "executor/spi.h"
 #include "nodes/nodeFuncs.h"
 #include "optimizer/planmain.h"
 #include "storage/lmgr.h"
@@ -502,8 +503,19 @@ RevalidateCachedPlan(CachedPlanSource *plansource, bool useResOwner)
                {
                        /*
                         * 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);
+
+                       SPI_pop_conditional(pushed);
                }
 
                /*