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Fix SPI cursor support to allow scanning the results of utility commands

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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.
This commit is contained in:
Tom Lane 2005-02-10 20:36:28 +00:00
parent 5cc8884a5d
commit 42599b322d
2 changed files with 54 additions and 15 deletions
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40
src/backend/executor/spi.c
View File

@ -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;

29
src/backend/tcop/pquery.c
View File

@ -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)
{