Re: Identity projection - Mailing list pgsql-hackers

Hello, This is new version of identity projection patch.

Reverted projectionInfo and ExecBuildProjectionInfo. Identity
projection is recognized directly in ExecGroup, ExecResult, and
ExecWindowAgg. nodeAgg is reverted because I couldn't make it
sane..

The following is the result of performance test posted before in
order to show the source of the gain.

regards,

-- 
-- 
Kyotaro Horiguchi
NTT Open Source Software Center



At Fri, 05 Oct 2012 16:04:16 +0900, Kyotaro HORIGUCHI wrote in
<20121005.160416.256387378.horiguchi.kyotaro@lab.ntt.co.jp>
> > Although I said as following, the gain seems a bit larger... I'll
> > recheck the testing conditions...
> 
> I had inspected more precisely on two aspects maginifying the
> effect of this patch by putting 300 columns into table.
> 
> 
> First, explain analyze says the difference caused by this patch
> is only in the actual time of Result node.
> 
> orig$ psql -c 'explain analyze select * from parenta'
>                           QUERY PLAN
> --------------------------------------------------------------------------
>  Result  (cost=0.00..176667.00 rows=1000001 width=1202)
>          (actual time=0.013.. *2406.792* rows=1000000 loops=1)
>    ->  Append  (cost=0.00..176667.00 rows=1000001 width=1202)
>                (actual time=0.011..412.749 rows=1000000 loops=1)
>          ->  Seq Scan on parenta  (cost=0.00..0.00 rows=1 width=1228)
>                                   (actual time=0.001..0.001 rows=0 loops=1)
>          ->  Seq Scan on childa000 parenta
>                             (cost=0.00..176667.00 rows=1000000 width=1202)
>                             (actual time=0.009..334.633 rows=1000000 loops=1)
>  Total runtime: 2446.474 ms
> (5 rows)
> 
> patched$ psql -c 'explain analyze select * from parenta'
>                           QUERY PLAN
> --------------------------------------------------------------------------
>  Result  (cost=0.00..176667.00 rows=1000001 width=1202)
>          (actual time=0.011.. *507.239* rows=1000000 loops=1)
>    ->  Append  (cost=0.00..176667.00 rows=1000001 width=1202)
>                (actual time=0.011..419.420 rows=1000000 loops=1)
>          ->  Seq Scan on parenta  (cost=0.00..0.00 rows=1 width=1228)
>                                   (actual time=0.000..0.000 rows=0 loops=1)
>          ->  Seq Scan on childa000 parenta
>                             (cost=0.00..176667.00 rows=1000000 width=1202)
>                             (actual time=0.010..335.721 rows=1000000 loops=1)
>  Total runtime: 545.879 ms
> (5 rows)
> 
> 
>  Second, the results of configure --enable-profiling shows that
> the exectime of ExecProject chages greately. This is consistent
> with what explain showed.
> 
> orig:
>  >  %   cumulative   self              self     total           
>  > time   seconds   seconds    calls   s/call   s/call  name    
>  > 60.29      1.26     1.26  1000005     0.00     0.00  slot_deform_tuple
> !> 30.14      1.89     0.63  1000000     0.00     0.00  ExecProject
>  >  3.35      1.96     0.07  3000004     0.00     0.00  ExecProcNode
>  >  0.96      1.98     0.02  1000002     0.00     0.00  ExecScan
>  >  0.96      2.00     0.02   166379     0.00     0.00  TerminateBufferIO
>  >  0.48      2.01     0.01  3000004     0.00     0.00  InstrStartNode
>  >  0.48      2.02     0.01  3000004     0.00     0.00  InstrStopNode
> !>  0.48      2.03     0.01  1000001     0.00     0.00  ExecResult
>  >  0.48      2.04     0.01   830718     0.00     0.00  LWLockAcquire
>  >  0.48      2.05     0.01   506834     0.00     0.00  hash_search_with_hash_value
>  >  0.48      2.06     0.01   341656     0.00     0.00  LockBuffer
>  >  0.48      2.07     0.01   168383     0.00     0.00  ReadBuffer_common
>  >  0.48      2.08     0.01        4     0.00     0.00  InstrEndLoop
>  >  0.48      2.09     0.01                             ExecCleanTargetListLength
>  >  0.00      2.09     0.00  2000005     0.00     0.00  MemoryContextReset
> 
> patched:
>  >   %   cumulative   self              self     total           
>  >  time   seconds   seconds    calls  ms/call  ms/call  name    
>  >  23.08      0.03     0.03  3000004     0.00     0.00  ExecProcNode
>  >  15.38      0.05     0.02  1000002     0.00     0.00  heapgettup_pagemode
>  >  15.38      0.07     0.02   830718     0.00     0.00  LWLockAcquire
>  >   7.69      0.08     0.01  2000005     0.00     0.00  MemoryContextReset
>  >   7.69      0.09     0.01  1000002     0.00     0.00  ExecScan
>  >   7.69      0.10     0.01  1000000     0.00     0.00  ExecStoreTuple
>  >   7.69      0.11     0.01   841135     0.00     0.00  LWLockRelease
>  >   7.69      0.12     0.01   168383     0.00     0.00  ReadBuffer_common
>  >   7.69      0.13     0.01   168383     0.00     0.00  UnpinBuffer
>  >   0.00      0.13     0.00  3000004     0.00     0.00  InstrStartNode
>  ...
> !>   0.00      0.13     0.00  1000001     0.00     0.00  ExecResult
> !>   0.00      0.13     0.00  1000000     0.00     0.00  ExecProject
==============================
diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index a8a1fe6..38037f9 100644
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -110,7 +110,10 @@ ExecGroup(GroupState *node)            TupleTableSlot *result;            ExprDoneCond isDone;
-            result = ExecProject(node->ss.ps.ps_ProjInfo, &isDone);
+            if (node->ss.ps.ps_ProjInfo)
+                result = ExecProject(node->ss.ps.ps_ProjInfo, &isDone);
+            else  /* Assign outertuple for identity projection */
+                result = econtext->ecxt_outertuple;            if (isDone != ExprEndResult)            {
@@ -173,7 +176,10 @@ ExecGroup(GroupState *node)            TupleTableSlot *result;            ExprDoneCond isDone;
-            result = ExecProject(node->ss.ps.ps_ProjInfo, &isDone);
+            if (node->ss.ps.ps_ProjInfo)
+                result = ExecProject(node->ss.ps.ps_ProjInfo, &isDone);
+            else  /* Assign outertuple for identity projection */
+                result = econtext->ecxt_outertuple;            if (isDone != ExprEndResult)            {
@@ -244,7 +250,10 @@ ExecInitGroup(Group *node, EState *estate, int eflags)     * Initialize result tuple type and
projectioninfo.     */    ExecAssignResultTypeFromTL(&grpstate->ss.ps);
 
-    ExecAssignProjectionInfo(&grpstate->ss.ps, NULL);
+    if (node->plan.tlist_lower_congruent)
+        grpstate->ss.ps.ps_ProjInfo = NULL;
+    else
+        ExecAssignProjectionInfo(&grpstate->ss.ps, NULL);    grpstate->ss.ps.ps_TupFromTlist = false;
diff --git a/src/backend/executor/nodeResult.c b/src/backend/executor/nodeResult.c
index b51efd8..4a129d6 100644
--- a/src/backend/executor/nodeResult.c
+++ b/src/backend/executor/nodeResult.c
@@ -152,7 +152,10 @@ ExecResult(ResultState *node)         * the projection produces an empty set, in which case we
mustloop         * back to see if there are more outerPlan tuples.         */
 
-        resultSlot = ExecProject(node->ps.ps_ProjInfo, &isDone);
+        if (node->ps.ps_ProjInfo)
+            resultSlot = ExecProject(node->ps.ps_ProjInfo, &isDone);
+        else  /* Assign outertuple for identity projection */
+            resultSlot = econtext->ecxt_outertuple;        if (isDone != ExprEndResult)        {
@@ -261,7 +264,10 @@ ExecInitResult(Result *node, EState *estate, int eflags)     * initialize tuple type and
projectioninfo     */    ExecAssignResultTypeFromTL(&resstate->ps);
 
-    ExecAssignProjectionInfo(&resstate->ps, NULL);
+    if (node->plan.tlist_lower_congruent)
+        resstate->ps.ps_ProjInfo = NULL;
+    else
+        ExecAssignProjectionInfo(&resstate->ps, NULL);    return resstate;}
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index ade9b57..d34c45a 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -1373,7 +1373,10 @@ restart:     * evaluated with respect to that row.     */    econtext->ecxt_outertuple =
winstate->ss.ss_ScanTupleSlot;
-    result = ExecProject(winstate->ss.ps.ps_ProjInfo, &isDone);
+    if (winstate->ss.ps.ps_ProjInfo)
+        result = ExecProject(winstate->ss.ps.ps_ProjInfo, &isDone);
+    else  /* Assign outertuple for identity projection */
+        result = econtext->ecxt_outertuple;    if (isDone == ExprEndResult)    {
@@ -1490,7 +1493,10 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)     * Initialize result tuple
typeand projection info.     */    ExecAssignResultTypeFromTL(&winstate->ss.ps);
 
-    ExecAssignProjectionInfo(&winstate->ss.ps, NULL);
+    if (node->plan.tlist_lower_congruent)
+        winstate->ss.ps.ps_ProjInfo = NULL;
+    else
+        ExecAssignProjectionInfo(&winstate->ss.ps, NULL);    winstate->ss.ps.ps_TupFromTlist = false;
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index ccd69fc..39d54ce 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -1184,6 +1184,7 @@ set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset)    indexed_tlist
*subplan_itlist;   List       *output_targetlist;    ListCell   *l;
 
+    int         nmatch = 0;    subplan_itlist = build_tlist_index(subplan->targetlist);
@@ -1214,12 +1215,25 @@ set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset)
     subplan_itlist,                                     OUTER_VAR,                                     rtoffset);
 
+        
+        if (IsA(newexpr, Var) && ((Var*)newexpr)->varattno == nmatch + 1)
+            nmatch++;
+        tle = flatCopyTargetEntry(tle);        tle->expr = (Expr *) newexpr;        output_targetlist =
lappend(output_targetlist,tle);    }
 
-    plan->targetlist = output_targetlist;
+    /*
+     * Directly refer to the lower tuple slot on projection if the all elements
+     * in target list exactly correspond to the ones in the lower tlist.
+     */
+    plan->tlist_lower_congruent  =
+        (nmatch == list_length(plan->targetlist) &&
+         nmatch == list_length(subplan->targetlist));
+
+    plan->targetlist = output_targetlist;
+     plan->qual = (List *)        fix_upper_expr(root,                       (Node *) plan->qual,
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index fb9a863..9e7729c 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -106,6 +106,7 @@ typedef struct Plan     * Common structural data for all Plan types.     */    List
*targetlist;       /* target list to be computed at this node */
 
+    bool        tlist_lower_congruent; /* target list is lower-congruent */    List       *qual;            /*
implicitly-ANDedqual conditions */    struct Plan *lefttree;        /* input plan tree(s) */    struct Plan *righttree;