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.

diff --git a/src/backend/commands/command.c b/src/backend/commands/command.c
index 646511eb18da7e2817c21a6f546a622f845cc644..9b1a33673c737eb2b7012f92ee8018bed7ef136c 100644 (file)
--- a/src/backend/commands/command.c
+++ b/src/backend/commands/command.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.152 2002/01/03 23:19:30 tgl Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.153 2002/02/14 15:24:06 tgl Exp $
  *
  * NOTES
  *   The PerformAddAttribute() code, like most of the relation
@@ -103,6 +103,7 @@ PerformPortalFetch(char *name,
    QueryDesc  *queryDesc;
    EState     *estate;
    MemoryContext oldcontext;
+   CommandId   savedId;
    bool        temp_desc = false;
 
    /*
@@ -156,7 +157,7 @@ PerformPortalFetch(char *name,
    }
 
    /*
-    * tell the destination to prepare to receive some tuples.
+    * Tell the destination to prepare to receive some tuples.
     */
    BeginCommand(name,
                 queryDesc->operation,
@@ -168,6 +169,14 @@ PerformPortalFetch(char *name,
                 tag,
                 queryDesc->dest);
 
+   /*
+    * Restore the scanCommandId that was current when the cursor was
+    * opened.  This ensures that we see the same tuples throughout the
+    * execution of the cursor.
+    */
+   savedId = GetScanCommandId();
+   SetScanCommandId(PortalGetCommandId(portal));
+
    /*
     * Determine which direction to go in, and check to see if we're
     * already at the end of the available tuples in that direction.  If
@@ -214,6 +223,11 @@ PerformPortalFetch(char *name,
        }
    }
 
+   /*
+    * Restore outer command ID.
+    */
+   SetScanCommandId(savedId);
+
    /*
     * Clean up and switch back to old context.
     */

diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index 064b0255222ef86a9a52e99f1a1221eec5bd70fd..b9ab64226585e7f3a2ca5c48602cf6d4eeac1ec7 100644 (file)
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/executor/spi.c,v 1.64 2002/01/03 20:30:47 tgl Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/executor/spi.c,v 1.65 2002/02/14 15:24:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -740,9 +740,9 @@ SPI_cursor_open(char *name, void *plan, Datum *Values, char *Nulls)
    _SPI_current->processed = 0;
    _SPI_current->tuptable = NULL;
 
-   /* Make up a portal name if none given */
    if (name == NULL)
    {
+       /* Make up a portal name if none given */
        for (;;)
        {
            unnamed_portal_count++;
@@ -755,11 +755,13 @@ SPI_cursor_open(char *name, void *plan, Datum *Values, char *Nulls)
 
        name = portalname;
    }
-
-   /* Ensure the portal doesn't exist already */
-   portal = GetPortalByName(name);
-   if (portal != NULL)
-       elog(ERROR, "cursor \"%s\" already in use", name);
+   else
+   {
+       /* Ensure the portal doesn't exist already */
+       portal = GetPortalByName(name);
+       if (portal != NULL)
+           elog(ERROR, "cursor \"%s\" already in use", name);
+   }
 
    /* Create the portal */
    portal = CreatePortal(name);
@@ -1228,6 +1230,7 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
    QueryDesc  *querydesc;
    EState     *estate;
    MemoryContext oldcontext;
+   CommandId   savedId;
    CommandDest olddest;
 
    /* Check that the portal is valid */
@@ -1245,6 +1248,7 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
 
    /* Switch to the portals memory context */
    oldcontext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
+
    querydesc = PortalGetQueryDesc(portal);
    estate = PortalGetState(portal);
 
@@ -1253,6 +1257,14 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
    olddest = querydesc->dest;
    querydesc->dest = dest;
 
+   /*
+    * Restore the scanCommandId that was current when the cursor was
+    * opened.  This ensures that we see the same tuples throughout the
+    * execution of the cursor.
+    */
+   savedId = GetScanCommandId();
+   SetScanCommandId(PortalGetCommandId(portal));
+
    /* Run the executor like PerformPortalFetch and remember states */
    if (forward)
    {
@@ -1279,6 +1291,11 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
        }
    }
 
+   /*
+    * Restore outer command ID.
+    */
+   SetScanCommandId(savedId);
+
    /* Restore the old command destination and switch back to callers */
    /* memory context */
    querydesc->dest = olddest;

diff --git a/src/backend/utils/mmgr/portalmem.c b/src/backend/utils/mmgr/portalmem.c
index 25171ea7bee94a03ba0c5b3bc1330fee120abe80..7682752922440ddcc85d4351ffdfe795c7024f72 100644 (file)
--- a/src/backend/utils/mmgr/portalmem.c
+++ b/src/backend/utils/mmgr/portalmem.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/utils/mmgr/portalmem.c,v 1.44 2001/10/25 05:49:51 momjian Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/utils/mmgr/portalmem.c,v 1.45 2002/02/14 15:24:09 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -168,6 +168,7 @@ PortalSetQuery(Portal portal,
 
    portal->queryDesc = queryDesc;
    portal->attinfo = attinfo;
+   portal->commandId = GetScanCommandId();
    portal->state = state;
    portal->atStart = true;     /* Allow fetch forward only */
    portal->atEnd = false;
@@ -213,6 +214,7 @@ CreatePortal(char *name)
    /* initialize portal query */
    portal->queryDesc = NULL;
    portal->attinfo = NULL;
+   portal->commandId = 0;
    portal->state = NULL;
    portal->atStart = true;     /* disallow fetches until query is set */
    portal->atEnd = true;

diff --git a/src/include/utils/portal.h b/src/include/utils/portal.h
index 395409ad205d9e3538480bd9c5a683accbf6fccd..9198b21feb9f53194aa779e474931519cd8ee67c 100644 (file)
--- a/src/include/utils/portal.h
+++ b/src/include/utils/portal.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: portal.h,v 1.31 2001/11/05 17:46:36 momjian Exp $
+ * $Id: portal.h,v 1.32 2002/02/14 15:24:10 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -31,6 +31,7 @@ typedef struct PortalData
    MemoryContext heap;         /* subsidiary memory */
    QueryDesc  *queryDesc;      /* Info about query associated with portal */
    TupleDesc   attinfo;
+   CommandId   commandId;      /* Command counter value for query */
    EState     *state;          /* Execution state of query */
    bool        atStart;        /* T => fetch backwards is not allowed */
    bool        atEnd;          /* T => fetch forwards is not allowed */
@@ -48,8 +49,9 @@ typedef struct PortalData
  */
 #define PortalGetQueryDesc(portal) ((portal)->queryDesc)
 #define PortalGetTupleDesc(portal) ((portal)->attinfo)
-#define PortalGetState(portal) ((portal)->state)
-#define PortalGetHeapMemory(portal)  ((portal)->heap)
+#define PortalGetCommandId(portal) ((portal)->commandId)
+#define PortalGetState(portal)     ((portal)->state)
+#define PortalGetHeapMemory(portal)    ((portal)->heap)
 
 /*
  * estimate of the maximum number of open portals a user would have,