Postpone some more stuff out of ExecInitModifyTable.
authorTom Lane <tgl@sss.pgh.pa.us>
Tue, 6 Apr 2021 22:13:05 +0000 (18:13 -0400)
committerTom Lane <tgl@sss.pgh.pa.us>
Tue, 6 Apr 2021 22:13:17 +0000 (18:13 -0400)
Delay creation of the projections for INSERT and UPDATE tuples
until they're needed.  This saves a pretty fair amount of work
when only some of the partitions are actually touched.

The logic associated with identifying junk columns in UPDATE/DELETE
is moved to another loop, allowing removal of one loop over the
target relations; but it didn't actually change at all.

Extracted from a larger patch, which seemed to me to be too messy
to push in one commit.

Amit Langote, reviewed at different times by Heikki Linnakangas and
myself

Discussion: https://postgr.es/m/CA+HiwqG7ZruBmmih3wPsBZ4s0H2EhywrnXEduckY5Hr3fWzPWA@mail.gmail.com

src/backend/executor/execMain.c
src/backend/executor/nodeModifyTable.c
src/include/nodes/execnodes.h

index bf43e7d379ea8a3e5ad911e3b43da551182993fb..78ddbf95f6805574771694efd39f4fc648a79e1f 100644 (file)
@@ -1221,6 +1221,7 @@ InitResultRelInfo(ResultRelInfo *resultRelInfo,
        resultRelInfo->ri_projectNew = NULL;
        resultRelInfo->ri_newTupleSlot = NULL;
        resultRelInfo->ri_oldTupleSlot = NULL;
+       resultRelInfo->ri_projectNewInfoValid = false;
        resultRelInfo->ri_FdwState = NULL;
        resultRelInfo->ri_usesFdwDirectModify = false;
        resultRelInfo->ri_ConstraintExprs = NULL;
index 249555f234bc43a9033a622090225342125cfde6..6a16752c73a10713c421ff6b28a3ee4520d08e24 100644 (file)
@@ -371,6 +371,139 @@ ExecComputeStoredGenerated(ResultRelInfo *resultRelInfo,
        MemoryContextSwitchTo(oldContext);
 }
 
+/*
+ * ExecInitInsertProjection
+ *             Do one-time initialization of projection data for INSERT tuples.
+ *
+ * INSERT queries may need a projection to filter out junk attrs in the tlist.
+ *
+ * This is "one-time" for any given result rel, but we might touch
+ * more than one result rel in the course of a partitioned INSERT.
+ *
+ * This is also a convenient place to verify that the
+ * output of an INSERT matches the target table.
+ */
+static void
+ExecInitInsertProjection(ModifyTableState *mtstate,
+                                                ResultRelInfo *resultRelInfo)
+{
+       ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
+       Plan       *subplan = outerPlan(node);
+       EState     *estate = mtstate->ps.state;
+       List       *insertTargetList = NIL;
+       bool            need_projection = false;
+       ListCell   *l;
+
+       /* Extract non-junk columns of the subplan's result tlist. */
+       foreach(l, subplan->targetlist)
+       {
+               TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+               if (!tle->resjunk)
+                       insertTargetList = lappend(insertTargetList, tle);
+               else
+                       need_projection = true;
+       }
+
+       /*
+        * The junk-free list must produce a tuple suitable for the result
+        * relation.
+        */
+       ExecCheckPlanOutput(resultRelInfo->ri_RelationDesc, insertTargetList);
+
+       /* We'll need a slot matching the table's format. */
+       resultRelInfo->ri_newTupleSlot =
+               table_slot_create(resultRelInfo->ri_RelationDesc,
+                                                 &estate->es_tupleTable);
+
+       /* Build ProjectionInfo if needed (it probably isn't). */
+       if (need_projection)
+       {
+               TupleDesc       relDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);
+
+               /* need an expression context to do the projection */
+               if (mtstate->ps.ps_ExprContext == NULL)
+                       ExecAssignExprContext(estate, &mtstate->ps);
+
+               resultRelInfo->ri_projectNew =
+                       ExecBuildProjectionInfo(insertTargetList,
+                                                                       mtstate->ps.ps_ExprContext,
+                                                                       resultRelInfo->ri_newTupleSlot,
+                                                                       &mtstate->ps,
+                                                                       relDesc);
+       }
+
+       resultRelInfo->ri_projectNewInfoValid = true;
+}
+
+/*
+ * ExecInitUpdateProjection
+ *             Do one-time initialization of projection data for UPDATE tuples.
+ *
+ * UPDATE always needs a projection, because (1) there's always some junk
+ * attrs, and (2) we may need to merge values of not-updated columns from
+ * the old tuple into the final tuple.  In UPDATE, the tuple arriving from
+ * the subplan contains only new values for the changed columns, plus row
+ * identity info in the junk attrs.
+ *
+ * This is "one-time" for any given result rel, but we might touch more than
+ * one result rel in the course of a partitioned UPDATE, and each one needs
+ * its own projection due to possible column order variation.
+ *
+ * This is also a convenient place to verify that the output of an UPDATE
+ * matches the target table (ExecBuildUpdateProjection does that).
+ */
+static void
+ExecInitUpdateProjection(ModifyTableState *mtstate,
+                                                ResultRelInfo *resultRelInfo)
+{
+       ModifyTable *node = (ModifyTable *) mtstate->ps.plan;
+       Plan       *subplan = outerPlan(node);
+       EState     *estate = mtstate->ps.state;
+       TupleDesc       relDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);
+       int                     whichrel;
+       List       *updateColnos;
+
+       /*
+        * Usually, mt_lastResultIndex matches the target rel.  If it happens not
+        * to, we can get the index the hard way with an integer division.
+        */
+       whichrel = mtstate->mt_lastResultIndex;
+       if (resultRelInfo != mtstate->resultRelInfo + whichrel)
+       {
+               whichrel = resultRelInfo - mtstate->resultRelInfo;
+               Assert(whichrel >= 0 && whichrel < mtstate->mt_nrels);
+       }
+
+       updateColnos = (List *) list_nth(node->updateColnosLists, whichrel);
+
+       /*
+        * For UPDATE, we use the old tuple to fill up missing values in the tuple
+        * produced by the subplan to get the new tuple.  We need two slots, both
+        * matching the table's desired format.
+        */
+       resultRelInfo->ri_oldTupleSlot =
+               table_slot_create(resultRelInfo->ri_RelationDesc,
+                                                 &estate->es_tupleTable);
+       resultRelInfo->ri_newTupleSlot =
+               table_slot_create(resultRelInfo->ri_RelationDesc,
+                                                 &estate->es_tupleTable);
+
+       /* need an expression context to do the projection */
+       if (mtstate->ps.ps_ExprContext == NULL)
+               ExecAssignExprContext(estate, &mtstate->ps);
+
+       resultRelInfo->ri_projectNew =
+               ExecBuildUpdateProjection(subplan->targetlist,
+                                                                 updateColnos,
+                                                                 relDesc,
+                                                                 mtstate->ps.ps_ExprContext,
+                                                                 resultRelInfo->ri_newTupleSlot,
+                                                                 &mtstate->ps);
+
+       resultRelInfo->ri_projectNewInfoValid = true;
+}
+
 /*
  * ExecGetInsertNewTuple
  *             This prepares a "new" tuple ready to be inserted into given result
@@ -429,6 +562,8 @@ ExecGetUpdateNewTuple(ResultRelInfo *relinfo,
        ProjectionInfo *newProj = relinfo->ri_projectNew;
        ExprContext *econtext;
 
+       /* Use a few extra Asserts to protect against outside callers */
+       Assert(relinfo->ri_projectNewInfoValid);
        Assert(planSlot != NULL && !TTS_EMPTY(planSlot));
        Assert(oldSlot != NULL && !TTS_EMPTY(oldSlot));
 
@@ -1375,8 +1510,12 @@ ExecCrossPartitionUpdate(ModifyTableState *mtstate,
                else
                {
                        /* Fetch the most recent version of old tuple. */
-                       TupleTableSlot *oldSlot = resultRelInfo->ri_oldTupleSlot;
+                       TupleTableSlot *oldSlot;
 
+                       /* ... but first, make sure ri_oldTupleSlot is initialized. */
+                       if (unlikely(!resultRelInfo->ri_projectNewInfoValid))
+                               ExecInitUpdateProjection(mtstate, resultRelInfo);
+                       oldSlot = resultRelInfo->ri_oldTupleSlot;
                        if (!table_tuple_fetch_row_version(resultRelInfo->ri_RelationDesc,
                                                                                           tupleid,
                                                                                           SnapshotAny,
@@ -1706,6 +1845,10 @@ lreplace:;
                                                                /* Tuple not passing quals anymore, exiting... */
                                                                return NULL;
 
+                                                       /* Make sure ri_oldTupleSlot is initialized. */
+                                                       if (unlikely(!resultRelInfo->ri_projectNewInfoValid))
+                                                               ExecInitUpdateProjection(mtstate, resultRelInfo);
+
                                                        /* Fetch the most recent version of old tuple. */
                                                        oldSlot = resultRelInfo->ri_oldTupleSlot;
                                                        if (!table_tuple_fetch_row_version(resultRelationDesc,
@@ -2388,11 +2531,17 @@ ExecModifyTable(PlanState *pstate)
                switch (operation)
                {
                        case CMD_INSERT:
+                               /* Initialize projection info if first time for this table */
+                               if (unlikely(!resultRelInfo->ri_projectNewInfoValid))
+                                       ExecInitInsertProjection(node, resultRelInfo);
                                slot = ExecGetInsertNewTuple(resultRelInfo, planSlot);
                                slot = ExecInsert(node, resultRelInfo, slot, planSlot,
                                                                  estate, node->canSetTag);
                                break;
                        case CMD_UPDATE:
+                               /* Initialize projection info if first time for this table */
+                               if (unlikely(!resultRelInfo->ri_projectNewInfoValid))
+                                       ExecInitUpdateProjection(node, resultRelInfo);
 
                                /*
                                 * Make the new tuple by combining plan's output tuple with
@@ -2665,8 +2814,65 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
                                                                                                                         i,
                                                                                                                         eflags);
                }
+
+               /*
+                * For UPDATE/DELETE, find the appropriate junk attr now, either a
+                * 'ctid' or 'wholerow' attribute depending on relkind.  For foreign
+                * tables, the FDW might have created additional junk attr(s), but
+                * those are no concern of ours.
+                */
+               if (operation == CMD_UPDATE || operation == CMD_DELETE)
+               {
+                       char            relkind;
+
+                       relkind = resultRelInfo->ri_RelationDesc->rd_rel->relkind;
+                       if (relkind == RELKIND_RELATION ||
+                               relkind == RELKIND_MATVIEW ||
+                               relkind == RELKIND_PARTITIONED_TABLE)
+                       {
+                               resultRelInfo->ri_RowIdAttNo =
+                                       ExecFindJunkAttributeInTlist(subplan->targetlist, "ctid");
+                               if (!AttributeNumberIsValid(resultRelInfo->ri_RowIdAttNo))
+                                       elog(ERROR, "could not find junk ctid column");
+                       }
+                       else if (relkind == RELKIND_FOREIGN_TABLE)
+                       {
+                               /*
+                                * When there is a row-level trigger, there should be a
+                                * wholerow attribute.  We also require it to be present in
+                                * UPDATE, so we can get the values of unchanged columns.
+                                */
+                               resultRelInfo->ri_RowIdAttNo =
+                                       ExecFindJunkAttributeInTlist(subplan->targetlist,
+                                                                                                "wholerow");
+                               if (mtstate->operation == CMD_UPDATE &&
+                                       !AttributeNumberIsValid(resultRelInfo->ri_RowIdAttNo))
+                                       elog(ERROR, "could not find junk wholerow column");
+                       }
+                       else
+                       {
+                               /* Other valid target relkinds must provide wholerow */
+                               resultRelInfo->ri_RowIdAttNo =
+                                       ExecFindJunkAttributeInTlist(subplan->targetlist,
+                                                                                                "wholerow");
+                               if (!AttributeNumberIsValid(resultRelInfo->ri_RowIdAttNo))
+                                       elog(ERROR, "could not find junk wholerow column");
+                       }
+               }
        }
 
+       /*
+        * If this is an inherited update/delete, there will be a junk attribute
+        * named "tableoid" present in the subplan's targetlist.  It will be used
+        * to identify the result relation for a given tuple to be
+        * updated/deleted.
+        */
+       mtstate->mt_resultOidAttno =
+               ExecFindJunkAttributeInTlist(subplan->targetlist, "tableoid");
+       Assert(AttributeNumberIsValid(mtstate->mt_resultOidAttno) || nrels == 1);
+       mtstate->mt_lastResultOid = InvalidOid; /* force lookup at first tuple */
+       mtstate->mt_lastResultIndex = 0;        /* must be zero if no such attr */
+
        /* Get the root target relation */
        rel = mtstate->rootResultRelInfo->ri_RelationDesc;
 
@@ -2842,163 +3048,6 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 
        EvalPlanQualSetPlan(&mtstate->mt_epqstate, subplan, arowmarks);
 
-       /*
-        * Initialize projection(s) to create tuples suitable for result rel(s).
-        * INSERT queries may need a projection to filter out junk attrs in the
-        * tlist.  UPDATE always needs a projection, because (1) there's always
-        * some junk attrs, and (2) we may need to merge values of not-updated
-        * columns from the old tuple into the final tuple.  In UPDATE, the tuple
-        * arriving from the subplan contains only new values for the changed
-        * columns, plus row identity info in the junk attrs.
-        *
-        * If there are multiple result relations, each one needs its own
-        * projection.  Note multiple rels are only possible for UPDATE/DELETE, so
-        * we can't be fooled by some needing a projection and some not.
-        *
-        * This section of code is also a convenient place to verify that the
-        * output of an INSERT or UPDATE matches the target table(s).
-        */
-       for (i = 0; i < nrels; i++)
-       {
-               resultRelInfo = &mtstate->resultRelInfo[i];
-
-               /*
-                * Prepare to generate tuples suitable for the target relation.
-                */
-               if (operation == CMD_INSERT)
-               {
-                       List       *insertTargetList = NIL;
-                       bool            need_projection = false;
-
-                       foreach(l, subplan->targetlist)
-                       {
-                               TargetEntry *tle = (TargetEntry *) lfirst(l);
-
-                               if (!tle->resjunk)
-                                       insertTargetList = lappend(insertTargetList, tle);
-                               else
-                                       need_projection = true;
-                       }
-
-                       /*
-                        * The junk-free list must produce a tuple suitable for the result
-                        * relation.
-                        */
-                       ExecCheckPlanOutput(resultRelInfo->ri_RelationDesc,
-                                                               insertTargetList);
-
-                       /* We'll need a slot matching the table's format. */
-                       resultRelInfo->ri_newTupleSlot =
-                               table_slot_create(resultRelInfo->ri_RelationDesc,
-                                                                 &mtstate->ps.state->es_tupleTable);
-
-                       /* Build ProjectionInfo if needed (it probably isn't). */
-                       if (need_projection)
-                       {
-                               TupleDesc       relDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);
-
-                               /* need an expression context to do the projection */
-                               if (mtstate->ps.ps_ExprContext == NULL)
-                                       ExecAssignExprContext(estate, &mtstate->ps);
-
-                               resultRelInfo->ri_projectNew =
-                                       ExecBuildProjectionInfo(insertTargetList,
-                                                                                       mtstate->ps.ps_ExprContext,
-                                                                                       resultRelInfo->ri_newTupleSlot,
-                                                                                       &mtstate->ps,
-                                                                                       relDesc);
-                       }
-               }
-               else if (operation == CMD_UPDATE)
-               {
-                       List       *updateColnos;
-                       TupleDesc       relDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);
-
-                       updateColnos = (List *) list_nth(node->updateColnosLists, i);
-
-                       /*
-                        * For UPDATE, we use the old tuple to fill up missing values in
-                        * the tuple produced by the plan to get the new tuple.  We need
-                        * two slots, both matching the table's desired format.
-                        */
-                       resultRelInfo->ri_oldTupleSlot =
-                               table_slot_create(resultRelInfo->ri_RelationDesc,
-                                                                 &mtstate->ps.state->es_tupleTable);
-                       resultRelInfo->ri_newTupleSlot =
-                               table_slot_create(resultRelInfo->ri_RelationDesc,
-                                                                 &mtstate->ps.state->es_tupleTable);
-
-                       /* need an expression context to do the projection */
-                       if (mtstate->ps.ps_ExprContext == NULL)
-                               ExecAssignExprContext(estate, &mtstate->ps);
-
-                       resultRelInfo->ri_projectNew =
-                               ExecBuildUpdateProjection(subplan->targetlist,
-                                                                                 updateColnos,
-                                                                                 relDesc,
-                                                                                 mtstate->ps.ps_ExprContext,
-                                                                                 resultRelInfo->ri_newTupleSlot,
-                                                                                 &mtstate->ps);
-               }
-
-               /*
-                * For UPDATE/DELETE, find the appropriate junk attr now, either a
-                * 'ctid' or 'wholerow' attribute depending on relkind.  For foreign
-                * tables, the FDW might have created additional junk attr(s), but
-                * those are no concern of ours.
-                */
-               if (operation == CMD_UPDATE || operation == CMD_DELETE)
-               {
-                       char            relkind;
-
-                       relkind = resultRelInfo->ri_RelationDesc->rd_rel->relkind;
-                       if (relkind == RELKIND_RELATION ||
-                               relkind == RELKIND_MATVIEW ||
-                               relkind == RELKIND_PARTITIONED_TABLE)
-                       {
-                               resultRelInfo->ri_RowIdAttNo =
-                                       ExecFindJunkAttributeInTlist(subplan->targetlist, "ctid");
-                               if (!AttributeNumberIsValid(resultRelInfo->ri_RowIdAttNo))
-                                       elog(ERROR, "could not find junk ctid column");
-                       }
-                       else if (relkind == RELKIND_FOREIGN_TABLE)
-                       {
-                               /*
-                                * When there is a row-level trigger, there should be a
-                                * wholerow attribute.  We also require it to be present in
-                                * UPDATE, so we can get the values of unchanged columns.
-                                */
-                               resultRelInfo->ri_RowIdAttNo =
-                                       ExecFindJunkAttributeInTlist(subplan->targetlist,
-                                                                                                "wholerow");
-                               if (mtstate->operation == CMD_UPDATE &&
-                                       !AttributeNumberIsValid(resultRelInfo->ri_RowIdAttNo))
-                                       elog(ERROR, "could not find junk wholerow column");
-                       }
-                       else
-                       {
-                               /* Other valid target relkinds must provide wholerow */
-                               resultRelInfo->ri_RowIdAttNo =
-                                       ExecFindJunkAttributeInTlist(subplan->targetlist,
-                                                                                                "wholerow");
-                               if (!AttributeNumberIsValid(resultRelInfo->ri_RowIdAttNo))
-                                       elog(ERROR, "could not find junk wholerow column");
-                       }
-               }
-       }
-
-       /*
-        * If this is an inherited update/delete, there will be a junk attribute
-        * named "tableoid" present in the subplan's targetlist.  It will be used
-        * to identify the result relation for a given tuple to be
-        * updated/deleted.
-        */
-       mtstate->mt_resultOidAttno =
-               ExecFindJunkAttributeInTlist(subplan->targetlist, "tableoid");
-       Assert(AttributeNumberIsValid(mtstate->mt_resultOidAttno) || nrels == 1);
-       mtstate->mt_lastResultOid = InvalidOid; /* force lookup at first tuple */
-       mtstate->mt_lastResultIndex = 0;        /* must be zero if no such attr */
-
        /*
         * If there are a lot of result relations, use a hash table to speed the
         * lookups.  If there are not a lot, a simple linear search is faster.
index 8116d62e814d4e7a317120368082b6a6fd28e98f..e7ae21c023c95e29526f59597774b43f44e411b2 100644 (file)
@@ -431,6 +431,8 @@ typedef struct ResultRelInfo
        TupleTableSlot *ri_newTupleSlot;
        /* Slot to hold the old tuple being updated */
        TupleTableSlot *ri_oldTupleSlot;
+       /* Have the projection and the slots above been initialized? */
+       bool            ri_projectNewInfoValid;
 
        /* triggers to be fired, if any */
        TriggerDesc *ri_TrigDesc;