Ensure that a cursor is scanned under the same scanCommandId it was
originally created with, so that the set of visible tuples does not change as a result of other activity. This essentially makes PG cursors INSENSITIVE per the SQL92 definition. See bug report of 13-Feb-02.
This commit is contained in:
Tom Lane
parent
1392042346
commit
3576820e78
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.152 2002/01/03 23:19:30 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.153 2002/02/14 15:24:06 tgl Exp $
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*
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* NOTES
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* The PerformAddAttribute() code, like most of the relation
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@ -103,6 +103,7 @@ PerformPortalFetch(char *name,
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QueryDesc *queryDesc;
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EState *estate;
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MemoryContext oldcontext;
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CommandId savedId;
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bool temp_desc = false;
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/*
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@ -156,7 +157,7 @@ PerformPortalFetch(char *name,
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}
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/*
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* tell the destination to prepare to receive some tuples.
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* Tell the destination to prepare to receive some tuples.
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*/
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BeginCommand(name,
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queryDesc->operation,
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@ -168,6 +169,14 @@ PerformPortalFetch(char *name,
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tag,
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queryDesc->dest);
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/*
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* Restore the scanCommandId that was current when the cursor was
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* opened. This ensures that we see the same tuples throughout the
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* execution of the cursor.
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*/
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savedId = GetScanCommandId();
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SetScanCommandId(PortalGetCommandId(portal));
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/*
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* Determine which direction to go in, and check to see if we're
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* already at the end of the available tuples in that direction. If
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@ -214,6 +223,11 @@ PerformPortalFetch(char *name,
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}
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}
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/*
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* Restore outer command ID.
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*/
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SetScanCommandId(savedId);
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/*
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* Clean up and switch back to old context.
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*/
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/executor/spi.c,v 1.64 2002/01/03 20:30:47 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/executor/spi.c,v 1.65 2002/02/14 15:24:08 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -740,9 +740,9 @@ SPI_cursor_open(char *name, void *plan, Datum *Values, char *Nulls)
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_SPI_current->processed = 0;
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_SPI_current->tuptable = NULL;
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/* Make up a portal name if none given */
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if (name == NULL)
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{
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/* Make up a portal name if none given */
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for (;;)
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{
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unnamed_portal_count++;
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@ -755,11 +755,13 @@ SPI_cursor_open(char *name, void *plan, Datum *Values, char *Nulls)
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name = portalname;
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}
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/* Ensure the portal doesn't exist already */
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portal = GetPortalByName(name);
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if (portal != NULL)
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elog(ERROR, "cursor \"%s\" already in use", name);
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else
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{
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/* Ensure the portal doesn't exist already */
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portal = GetPortalByName(name);
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if (portal != NULL)
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elog(ERROR, "cursor \"%s\" already in use", name);
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}
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/* Create the portal */
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portal = CreatePortal(name);
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@ -1228,6 +1230,7 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
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QueryDesc *querydesc;
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EState *estate;
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MemoryContext oldcontext;
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CommandId savedId;
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CommandDest olddest;
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/* Check that the portal is valid */
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@ -1245,6 +1248,7 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
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/* Switch to the portals memory context */
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oldcontext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
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querydesc = PortalGetQueryDesc(portal);
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estate = PortalGetState(portal);
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@ -1253,6 +1257,14 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
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olddest = querydesc->dest;
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querydesc->dest = dest;
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/*
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* Restore the scanCommandId that was current when the cursor was
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* opened. This ensures that we see the same tuples throughout the
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* execution of the cursor.
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*/
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savedId = GetScanCommandId();
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SetScanCommandId(PortalGetCommandId(portal));
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/* Run the executor like PerformPortalFetch and remember states */
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if (forward)
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{
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@ -1279,6 +1291,11 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
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}
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}
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/*
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* Restore outer command ID.
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*/
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SetScanCommandId(savedId);
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/* Restore the old command destination and switch back to callers */
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/* memory context */
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querydesc->dest = olddest;
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/utils/mmgr/portalmem.c,v 1.44 2001/10/25 05:49:51 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/utils/mmgr/portalmem.c,v 1.45 2002/02/14 15:24:09 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -168,6 +168,7 @@ PortalSetQuery(Portal portal,
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portal->queryDesc = queryDesc;
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portal->attinfo = attinfo;
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portal->commandId = GetScanCommandId();
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portal->state = state;
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portal->atStart = true; /* Allow fetch forward only */
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portal->atEnd = false;
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@ -213,6 +214,7 @@ CreatePortal(char *name)
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/* initialize portal query */
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portal->queryDesc = NULL;
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portal->attinfo = NULL;
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portal->commandId = 0;
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portal->state = NULL;
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portal->atStart = true; /* disallow fetches until query is set */
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portal->atEnd = true;
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: portal.h,v 1.31 2001/11/05 17:46:36 momjian Exp $
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* $Id: portal.h,v 1.32 2002/02/14 15:24:10 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -31,6 +31,7 @@ typedef struct PortalData
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MemoryContext heap; /* subsidiary memory */
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QueryDesc *queryDesc; /* Info about query associated with portal */
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TupleDesc attinfo;
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CommandId commandId; /* Command counter value for query */
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EState *state; /* Execution state of query */
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bool atStart; /* T => fetch backwards is not allowed */
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bool atEnd; /* T => fetch forwards is not allowed */
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@ -48,8 +49,9 @@ typedef struct PortalData
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*/
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#define PortalGetQueryDesc(portal) ((portal)->queryDesc)
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#define PortalGetTupleDesc(portal) ((portal)->attinfo)
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#define PortalGetState(portal) ((portal)->state)
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#define PortalGetHeapMemory(portal) ((portal)->heap)
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#define PortalGetCommandId(portal) ((portal)->commandId)
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#define PortalGetState(portal) ((portal)->state)
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#define PortalGetHeapMemory(portal) ((portal)->heap)
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/*
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* estimate of the maximum number of open portals a user would have,
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