Fix improper matching of resjunk column names for FOR UPDATE in subselect.

Flattening of subquery range tables during setrefs.c could lead to the
rangetable indexes in PlanRowMark nodes not matching up with the column
names previously assigned to the corresponding resjunk ctid (resp. tableoid
or wholerow) columns.  Typical symptom would be either a "cannot extract
system attribute from virtual tuple" error or an Assert failure.  This
wasn't a problem before 9.0 because we didn't support FOR UPDATE below the
top query level, and so the final flattening could never renumber an RTE
that was relevant to FOR UPDATE.  Fix by using a plan-tree-wide unique
number for each PlanRowMark to label the associated resjunk columns, so
that the number need not change during flattening.

Per report from David Johnston (though I'm darned if I can see how this got
past initial testing of the relevant code).  Back-patch to 9.0.

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 6d4a773..c477314 100644 (file)
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -726,6 +726,7 @@ InitPlan(QueryDesc *queryDesc, int eflags)
                erm->relation = relation;
                erm->rti = rc->rti;
                erm->prti = rc->prti;
+               erm->rowmarkId = rc->rowmarkId;
                erm->markType = rc->markType;
                erm->noWait = rc->noWait;
                ItemPointerSetInvalid(&(erm->curCtid));
@@ -1373,23 +1374,29 @@ ExecBuildAuxRowMark(ExecRowMark *erm, List *targetlist)
                /* if child rel, need tableoid */
                if (erm->rti != erm->prti)
                {
-                       snprintf(resname, sizeof(resname), "tableoid%u", erm->prti);
+                       snprintf(resname, sizeof(resname), "tableoid%u", erm->rowmarkId);
                        aerm->toidAttNo = ExecFindJunkAttributeInTlist(targetlist,
                                                                                                                   resname);
+                       if (!AttributeNumberIsValid(aerm->toidAttNo))
+                               elog(ERROR, "could not find junk %s column", resname);
                }
 
                /* always need ctid for real relations */
-               snprintf(resname, sizeof(resname), "ctid%u", erm->prti);
+               snprintf(resname, sizeof(resname), "ctid%u", erm->rowmarkId);
                aerm->ctidAttNo = ExecFindJunkAttributeInTlist(targetlist,
                                                                                                           resname);
+               if (!AttributeNumberIsValid(aerm->ctidAttNo))
+                       elog(ERROR, "could not find junk %s column", resname);
        }
        else
        {
                Assert(erm->markType == ROW_MARK_COPY);
 
-               snprintf(resname, sizeof(resname), "wholerow%u", erm->prti);
+               snprintf(resname, sizeof(resname), "wholerow%u", erm->rowmarkId);
                aerm->wholeAttNo = ExecFindJunkAttributeInTlist(targetlist,
                                                                                                                resname);
+               if (!AttributeNumberIsValid(aerm->wholeAttNo))
+                       elog(ERROR, "could not find junk %s column", resname);
        }
 
        return aerm;

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 0b2aa3d..778c530 100644 (file)
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -856,6 +856,7 @@ _copyPlanRowMark(PlanRowMark *from)
 
        COPY_SCALAR_FIELD(rti);
        COPY_SCALAR_FIELD(prti);
+       COPY_SCALAR_FIELD(rowmarkId);
        COPY_SCALAR_FIELD(markType);
        COPY_SCALAR_FIELD(noWait);
        COPY_SCALAR_FIELD(isParent);

diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 032150e..15a9aa2 100644 (file)
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -756,6 +756,7 @@ _outPlanRowMark(StringInfo str, PlanRowMark *node)
 
        WRITE_UINT_FIELD(rti);
        WRITE_UINT_FIELD(prti);
+       WRITE_UINT_FIELD(rowmarkId);
        WRITE_ENUM_FIELD(markType, RowMarkType);
        WRITE_BOOL_FIELD(noWait);
        WRITE_BOOL_FIELD(isParent);
@@ -1524,6 +1525,7 @@ _outPlannerGlobal(StringInfo str, PlannerGlobal *node)
        WRITE_NODE_FIELD(relationOids);
        WRITE_NODE_FIELD(invalItems);
        WRITE_UINT_FIELD(lastPHId);
+       WRITE_UINT_FIELD(lastRowMarkId);
        WRITE_BOOL_FIELD(transientPlan);
 }
 

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 45ba902..5520657 100644 (file)
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -165,6 +165,7 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
        glob->relationOids = NIL;
        glob->invalItems = NIL;
        glob->lastPHId = 0;
+       glob->lastRowMarkId = 0;
        glob->transientPlan = false;
 
        /* Determine what fraction of the plan is likely to be scanned */
@@ -1852,6 +1853,7 @@ preprocess_rowmarks(PlannerInfo *root)
 
                newrc = makeNode(PlanRowMark);
                newrc->rti = newrc->prti = rc->rti;
+               newrc->rowmarkId = ++(root->glob->lastRowMarkId);
                if (rc->forUpdate)
                        newrc->markType = ROW_MARK_EXCLUSIVE;
                else
@@ -1877,6 +1879,7 @@ preprocess_rowmarks(PlannerInfo *root)
 
                newrc = makeNode(PlanRowMark);
                newrc->rti = newrc->prti = i;
+               newrc->rowmarkId = ++(root->glob->lastRowMarkId);
                /* real tables support REFERENCE, anything else needs COPY */
                if (rte->rtekind == RTE_RELATION)
                        newrc->markType = ROW_MARK_REFERENCE;

diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 70be2e6..2618ef1 100644 (file)
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -252,7 +252,7 @@ set_plan_references(PlannerGlobal *glob, Plan *plan,
                newrc = (PlanRowMark *) palloc(sizeof(PlanRowMark));
                memcpy(newrc, rc, sizeof(PlanRowMark));
 
-               /* adjust indexes */
+               /* adjust indexes ... but *not* the rowmarkId */
                newrc->rti += rtoffset;
                newrc->prti += rtoffset;
 

diff --git a/src/backend/optimizer/prep/preptlist.c b/src/backend/optimizer/prep/preptlist.c
index 7a09d1f..425d80c 100644 (file)
--- a/src/backend/optimizer/prep/preptlist.c
+++ b/src/backend/optimizer/prep/preptlist.c
@@ -132,7 +132,7 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
                                                  TIDOID,
                                                  -1,
                                                  0);
-                       snprintf(resname, sizeof(resname), "ctid%u", rc->rti);
+                       snprintf(resname, sizeof(resname), "ctid%u", rc->rowmarkId);
                        tle = makeTargetEntry((Expr *) var,
                                                                  list_length(tlist) + 1,
                                                                  pstrdup(resname),
@@ -147,7 +147,7 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
                                                          OIDOID,
                                                          -1,
                                                          0);
-                               snprintf(resname, sizeof(resname), "tableoid%u", rc->rti);
+                               snprintf(resname, sizeof(resname), "tableoid%u", rc->rowmarkId);
                                tle = makeTargetEntry((Expr *) var,
                                                                          list_length(tlist) + 1,
                                                                          pstrdup(resname),
@@ -161,7 +161,7 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
                        var = makeWholeRowVar(rt_fetch(rc->rti, range_table),
                                                                  rc->rti,
                                                                  0);
-                       snprintf(resname, sizeof(resname), "wholerow%u", rc->rti);
+                       snprintf(resname, sizeof(resname), "wholerow%u", rc->rowmarkId);
                        tle = makeTargetEntry((Expr *) var,
                                                                  list_length(tlist) + 1,
                                                                  pstrdup(resname),

diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 35f9f98..cabc93d 100644 (file)
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -1288,6 +1288,7 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
 
                        newrc->rti = childRTindex;
                        newrc->prti = rti;
+                       newrc->rowmarkId = oldrc->rowmarkId;
                        newrc->markType = oldrc->markType;
                        newrc->noWait = oldrc->noWait;
                        newrc->isParent = false;

diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index fda4425..ac0de09 100644 (file)
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -417,6 +417,7 @@ typedef struct ExecRowMark
        Relation        relation;               /* opened and suitably locked relation */
        Index           rti;                    /* its range table index */
        Index           prti;                   /* parent range table index, if child */
+       Index           rowmarkId;              /* unique identifier for resjunk columns */
        RowMarkType markType;           /* see enum in nodes/plannodes.h */
        bool            noWait;                 /* NOWAIT option */
        ItemPointerData curCtid;        /* ctid of currently locked tuple, if any */

diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index e142579..729e355 100644 (file)
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -701,7 +701,11 @@ typedef enum RowMarkType
  * The tableoid column is only present for an inheritance hierarchy.
  * When markType == ROW_MARK_COPY, there is instead a single column named
  *             wholerow%u                      whole-row value of relation
- * In all three cases, %u represents the parent rangetable index (prti).
+ * In all three cases, %u represents the rowmark ID number (rowmarkId).
+ * This number is unique within a plan tree, except that child relation
+ * entries copy their parent's rowmarkId.  (Assigning unique numbers
+ * means we needn't renumber rowmarkIds when flattening subqueries, which
+ * would require finding and renaming the resjunk columns as well.)
  * Note this means that all tables in an inheritance hierarchy share the
  * same resjunk column names.  However, in an inherited UPDATE/DELETE the
  * columns could have different physical column numbers in each subplan.
@@ -711,6 +715,7 @@ typedef struct PlanRowMark
        NodeTag         type;
        Index           rti;                    /* range table index of markable relation */
        Index           prti;                   /* range table index of parent relation */
+       Index           rowmarkId;              /* unique identifier for resjunk columns */
        RowMarkType markType;           /* see enum above */
        bool            noWait;                 /* NOWAIT option */
        bool            isParent;               /* true if this is a "dummy" parent entry */

diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index a3678a5..f109a1d 100644 (file)
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -82,6 +82,8 @@ typedef struct PlannerGlobal
 
        Index           lastPHId;               /* highest PlaceHolderVar ID assigned */
 
+       Index           lastRowMarkId;  /* highest PlanRowMark ID assigned */
+
        bool            transientPlan;  /* redo plan when TransactionXmin changes? */
 } PlannerGlobal;