From 42599b322db75b1cfdf4ab518532ddffd15066ac Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 10 Feb 2005 20:36:28 +0000
Subject: [PATCH] Fix SPI cursor support to allow scanning the results of
utility commands that return tuples (such as EXPLAIN). Per gripe from
Michael Fuhr. Side effect: fix an old bug that unintentionally disabled
backward scans for all SPI-created cursors.
---
src/backend/executor/spi.c | 40 +++++++++++++++++++++++++-------------
src/backend/tcop/pquery.c | 29 +++++++++++++++++++++++++--
2 files changed, 54 insertions(+), 15 deletions(-)
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index a0bfdf12bc..fd860fcb55 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.133 2004/12/31 21:59:45 pgsql Exp $
+ * $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.134 2005/02/10 20:36:27 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -832,7 +832,7 @@ SPI_cursor_open(const char *name, void *plan,
Portal portal;
int k;
- /* Ensure that the plan contains only one regular SELECT query */
+ /* Ensure that the plan contains only one query */
if (list_length(ptlist) != 1 || list_length(qtlist) != 1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
@@ -840,14 +840,27 @@ SPI_cursor_open(const char *name, void *plan,
queryTree = (Query *) linitial((List *) linitial(qtlist));
planTree = (Plan *) linitial(ptlist);
- if (queryTree->commandType != CMD_SELECT)
- ereport(ERROR,
- (errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
- errmsg("cannot open non-SELECT query as cursor")));
- if (queryTree->into != NULL)
- ereport(ERROR,
- (errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
- errmsg("cannot open SELECT INTO query as cursor")));
+ /* Must be a query that returns tuples */
+ switch (queryTree->commandType)
+ {
+ case CMD_SELECT:
+ if (queryTree->into != NULL)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
+ errmsg("cannot open SELECT INTO query as cursor")));
+ break;
+ case CMD_UTILITY:
+ if (!UtilityReturnsTuples(queryTree->utilityStmt))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
+ errmsg("cannot open non-SELECT query as cursor")));
+ break;
+ default:
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
+ errmsg("cannot open non-SELECT query as cursor")));
+ break;
+ }
/* Reset SPI result */
SPI_processed = 0;
@@ -911,7 +924,7 @@ SPI_cursor_open(const char *name, void *plan,
*/
PortalDefineQuery(portal,
NULL, /* unfortunately don't have sourceText */
- "SELECT", /* cursor's query is always a SELECT */
+ "SELECT", /* nor the raw parse tree... */
list_make1(queryTree),
list_make1(planTree),
PortalGetHeapMemory(portal));
@@ -922,7 +935,7 @@ SPI_cursor_open(const char *name, void *plan,
* Set up options for portal.
*/
portal->cursorOptions &= ~(CURSOR_OPT_SCROLL | CURSOR_OPT_NO_SCROLL);
- if (ExecSupportsBackwardScan(plan))
+ if (planTree == NULL || ExecSupportsBackwardScan(planTree))
portal->cursorOptions |= CURSOR_OPT_SCROLL;
else
portal->cursorOptions |= CURSOR_OPT_NO_SCROLL;
@@ -944,7 +957,8 @@ SPI_cursor_open(const char *name, void *plan,
*/
PortalStart(portal, paramLI, snapshot);
- Assert(portal->strategy == PORTAL_ONE_SELECT);
+ Assert(portal->strategy == PORTAL_ONE_SELECT ||
+ portal->strategy == PORTAL_UTIL_SELECT);
/* Return the created portal */
return portal;
diff --git a/src/backend/tcop/pquery.c b/src/backend/tcop/pquery.c
index 496cbb43f8..d4d5b94594 100644
--- a/src/backend/tcop/pquery.c
+++ b/src/backend/tcop/pquery.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.90 2005/02/01 23:28:40 neilc Exp $
+ * $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.91 2005/02/10 20:36:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -1120,6 +1120,30 @@ PortalRunFetch(Portal portal,
result = DoPortalRunFetch(portal, fdirection, count, dest);
break;
+ case PORTAL_UTIL_SELECT:
+
+ /*
+ * If we have not yet run the utility statement, do so,
+ * storing its results in the portal's tuplestore.
+ */
+ if (!portal->portalUtilReady)
+ {
+ DestReceiver *treceiver;
+
+ PortalCreateHoldStore(portal);
+ treceiver = CreateDestReceiver(Tuplestore, portal);
+ PortalRunUtility(portal, linitial(portal->parseTrees),
+ treceiver, NULL);
+ (*treceiver->rDestroy) (treceiver);
+ portal->portalUtilReady = true;
+ }
+
+ /*
+ * Now fetch desired portion of results.
+ */
+ result = DoPortalRunFetch(portal, fdirection, count, dest);
+ break;
+
default:
elog(ERROR, "unsupported portal strategy");
result = 0; /* keep compiler quiet */
@@ -1170,7 +1194,8 @@ DoPortalRunFetch(Portal portal,
{
bool forward;
- Assert(portal->strategy == PORTAL_ONE_SELECT);
+ Assert(portal->strategy == PORTAL_ONE_SELECT ||
+ portal->strategy == PORTAL_UTIL_SELECT);
switch (fdirection)
{
--
2.49.0