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Rearrange the implementation of index-only scans.
This commit changes index-only scans so that data is read directly from the index tuple without first generating a faux heap tuple. The only immediate benefit is that indexes on system columns (such as OID) can be used in index-only scans, but this is necessary infrastructure if we are ever to support index-only scans on expression indexes. The executor is now ready for that, though the planner still needs substantial work to recognize the possibility. To do this, Vars in index-only plan nodes have to refer to index columns not heap columns. I introduced a new special varno, INDEX_VAR, to mark such Vars to avoid confusion. (In passing, this commit renames the two existing special varnos to OUTER_VAR and INNER_VAR.) This allows ruleutils.c to handle them with logic similar to what we use for subplan reference Vars. Since index-only scans are now fundamentally different from regular indexscans so far as their expression subtrees are concerned, I also chose to change them to have their own plan node type (and hence, their own executor source file).
1 parent fa351d5 commit a018546

34 files changed

+1313
-420
lines changed

‎src/backend/commands/explain.c

Lines changed: 79 additions & 40 deletions
Original file line numberDiff line numberDiff line change
@@ -79,6 +79,8 @@ static void show_instrumentation_count(const char *qlabel, int which,
7979
PlanState *planstate, ExplainState *es);
8080
static void show_foreignscan_info(ForeignScanState *fsstate, ExplainState *es);
8181
static const char *explain_get_index_name(Oid indexId);
82+
static void ExplainIndexScanDetails(Oid indexid, ScanDirection indexorderdir,
83+
ExplainState *es);
8284
static void ExplainScanTarget(Scan *plan, ExplainState *es);
8385
static void ExplainModifyTarget(ModifyTable *plan, ExplainState *es);
8486
static void ExplainTargetRel(Plan *plan, Index rti, ExplainState *es);
@@ -656,10 +658,10 @@ ExplainNode(PlanState *planstate, List *ancestors,
656658
pname = sname = "Seq Scan";
657659
break;
658660
case T_IndexScan:
659-
if (((IndexScan *) plan)->indexonly)
660-
pname = sname = "Index Only Scan";
661-
else
662-
pname = sname = "Index Scan";
661+
pname = sname = "Index Scan";
662+
break;
663+
case T_IndexOnlyScan:
664+
pname = sname = "Index Only Scan";
663665
break;
664666
case T_BitmapIndexScan:
665667
pname = sname = "Bitmap Index Scan";
@@ -793,42 +795,6 @@ ExplainNode(PlanState *planstate, List *ancestors,
793795

794796
switch (nodeTag(plan))
795797
{
796-
case T_IndexScan:
797-
{
798-
IndexScan *indexscan = (IndexScan *) plan;
799-
const char *indexname =
800-
explain_get_index_name(indexscan->indexid);
801-
802-
if (es->format == EXPLAIN_FORMAT_TEXT)
803-
{
804-
if (ScanDirectionIsBackward(indexscan->indexorderdir))
805-
appendStringInfoString(es->str, " Backward");
806-
appendStringInfo(es->str, " using %s", indexname);
807-
}
808-
else
809-
{
810-
const char *scandir;
811-
812-
switch (indexscan->indexorderdir)
813-
{
814-
case BackwardScanDirection:
815-
scandir = "Backward";
816-
break;
817-
case NoMovementScanDirection:
818-
scandir = "NoMovement";
819-
break;
820-
case ForwardScanDirection:
821-
scandir = "Forward";
822-
break;
823-
default:
824-
scandir = "???";
825-
break;
826-
}
827-
ExplainPropertyText("Scan Direction", scandir, es);
828-
ExplainPropertyText("Index Name", indexname, es);
829-
}
830-
}
831-
/* FALL THRU */
832798
case T_SeqScan:
833799
case T_BitmapHeapScan:
834800
case T_TidScan:
@@ -840,6 +806,26 @@ ExplainNode(PlanState *planstate, List *ancestors,
840806
case T_ForeignScan:
841807
ExplainScanTarget((Scan *) plan, es);
842808
break;
809+
case T_IndexScan:
810+
{
811+
IndexScan *indexscan = (IndexScan *) plan;
812+
813+
ExplainIndexScanDetails(indexscan->indexid,
814+
indexscan->indexorderdir,
815+
es);
816+
ExplainScanTarget((Scan *) indexscan, es);
817+
}
818+
break;
819+
case T_IndexOnlyScan:
820+
{
821+
IndexOnlyScan *indexonlyscan = (IndexOnlyScan *) plan;
822+
823+
ExplainIndexScanDetails(indexonlyscan->indexid,
824+
indexonlyscan->indexorderdir,
825+
es);
826+
ExplainScanTarget((Scan *) indexonlyscan, es);
827+
}
828+
break;
843829
case T_BitmapIndexScan:
844830
{
845831
BitmapIndexScan *bitmapindexscan = (BitmapIndexScan *) plan;
@@ -1014,6 +1000,19 @@ ExplainNode(PlanState *planstate, List *ancestors,
10141000
show_instrumentation_count("Rows Removed by Filter", 1,
10151001
planstate, es);
10161002
break;
1003+
case T_IndexOnlyScan:
1004+
show_scan_qual(((IndexOnlyScan *) plan)->indexqual,
1005+
"Index Cond", planstate, ancestors, es);
1006+
if (((IndexOnlyScan *) plan)->indexqual)
1007+
show_instrumentation_count("Rows Removed by Index Recheck", 2,
1008+
planstate, es);
1009+
show_scan_qual(((IndexOnlyScan *) plan)->indexorderby,
1010+
"Order By", planstate, ancestors, es);
1011+
show_scan_qual(plan->qual, "Filter", planstate, ancestors, es);
1012+
if (plan->qual)
1013+
show_instrumentation_count("Rows Removed by Filter", 1,
1014+
planstate, es);
1015+
break;
10171016
case T_BitmapIndexScan:
10181017
show_scan_qual(((BitmapIndexScan *) plan)->indexqualorig,
10191018
"Index Cond", planstate, ancestors, es);
@@ -1626,6 +1625,45 @@ explain_get_index_name(Oid indexId)
16261625
return result;
16271626
}
16281627

1628+
/*
1629+
* Add some additional details about an IndexScan or IndexOnlyScan
1630+
*/
1631+
static void
1632+
ExplainIndexScanDetails(Oid indexid, ScanDirection indexorderdir,
1633+
ExplainState *es)
1634+
{
1635+
const char *indexname = explain_get_index_name(indexid);
1636+
1637+
if (es->format == EXPLAIN_FORMAT_TEXT)
1638+
{
1639+
if (ScanDirectionIsBackward(indexorderdir))
1640+
appendStringInfoString(es->str, " Backward");
1641+
appendStringInfo(es->str, " using %s", indexname);
1642+
}
1643+
else
1644+
{
1645+
const char *scandir;
1646+
1647+
switch (indexorderdir)
1648+
{
1649+
case BackwardScanDirection:
1650+
scandir = "Backward";
1651+
break;
1652+
case NoMovementScanDirection:
1653+
scandir = "NoMovement";
1654+
break;
1655+
case ForwardScanDirection:
1656+
scandir = "Forward";
1657+
break;
1658+
default:
1659+
scandir = "???";
1660+
break;
1661+
}
1662+
ExplainPropertyText("Scan Direction", scandir, es);
1663+
ExplainPropertyText("Index Name", indexname, es);
1664+
}
1665+
}
1666+
16291667
/*
16301668
* Show the target of a Scan node
16311669
*/
@@ -1670,6 +1708,7 @@ ExplainTargetRel(Plan *plan, Index rti, ExplainState *es)
16701708
{
16711709
case T_SeqScan:
16721710
case T_IndexScan:
1711+
case T_IndexOnlyScan:
16731712
case T_BitmapHeapScan:
16741713
case T_TidScan:
16751714
case T_ForeignScan:

‎src/backend/commands/trigger.c

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -2734,9 +2734,9 @@ TriggerEnabled(EState *estate, ResultRelInfo *relinfo,
27342734

27352735
oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
27362736
tgqual = stringToNode(trigger->tgqual);
2737-
/* Change references to OLD and NEW to INNER and OUTER */
2738-
ChangeVarNodes(tgqual, PRS2_OLD_VARNO, INNER, 0);
2739-
ChangeVarNodes(tgqual, PRS2_NEW_VARNO, OUTER, 0);
2737+
/* Change references to OLD and NEW to INNER_VAR and OUTER_VAR */
2738+
ChangeVarNodes(tgqual, PRS2_OLD_VARNO, INNER_VAR, 0);
2739+
ChangeVarNodes(tgqual, PRS2_NEW_VARNO, OUTER_VAR, 0);
27402740
/* ExecQual wants implicit-AND form */
27412741
tgqual = (Node *) make_ands_implicit((Expr *) tgqual);
27422742
*predicate = (List *) ExecPrepareExpr((Expr *) tgqual, estate);
@@ -2783,7 +2783,7 @@ TriggerEnabled(EState *estate, ResultRelInfo *relinfo,
27832783

27842784
/*
27852785
* Finally evaluate the expression, making the old and/or new tuples
2786-
* available as INNER/OUTER respectively.
2786+
* available as INNER_VAR/OUTER_VAR respectively.
27872787
*/
27882788
econtext->ecxt_innertuple = oldslot;
27892789
econtext->ecxt_outertuple = newslot;

‎src/backend/executor/Makefile

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -17,7 +17,8 @@ OBJS = execAmi.o execCurrent.o execGrouping.o execJunk.o execMain.o \
1717
execUtils.o functions.o instrument.o nodeAppend.o nodeAgg.o \
1818
nodeBitmapAnd.o nodeBitmapOr.o \
1919
nodeBitmapHeapscan.o nodeBitmapIndexscan.o nodeHash.o \
20-
nodeHashjoin.o nodeIndexscan.o nodeLimit.o nodeLockRows.o \
20+
nodeHashjoin.o nodeIndexscan.o nodeIndexonlyscan.o \
21+
nodeLimit.o nodeLockRows.o \
2122
nodeMaterial.o nodeMergeAppend.o nodeMergejoin.o nodeModifyTable.o \
2223
nodeNestloop.o nodeFunctionscan.o nodeRecursiveunion.o nodeResult.o \
2324
nodeSeqscan.o nodeSetOp.o nodeSort.o nodeUnique.o \

‎src/backend/executor/execAmi.c

Lines changed: 20 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -26,6 +26,7 @@
2626
#include "executor/nodeGroup.h"
2727
#include "executor/nodeHash.h"
2828
#include "executor/nodeHashjoin.h"
29+
#include "executor/nodeIndexonlyscan.h"
2930
#include "executor/nodeIndexscan.h"
3031
#include "executor/nodeLimit.h"
3132
#include "executor/nodeLockRows.h"
@@ -155,6 +156,10 @@ ExecReScan(PlanState *node)
155156
ExecReScanIndexScan((IndexScanState *) node);
156157
break;
157158

159+
case T_IndexOnlyScanState:
160+
ExecReScanIndexOnlyScan((IndexOnlyScanState *) node);
161+
break;
162+
158163
case T_BitmapIndexScanState:
159164
ExecReScanBitmapIndexScan((BitmapIndexScanState *) node);
160165
break;
@@ -273,6 +278,10 @@ ExecMarkPos(PlanState *node)
273278
ExecIndexMarkPos((IndexScanState *) node);
274279
break;
275280

281+
case T_IndexOnlyScanState:
282+
ExecIndexOnlyMarkPos((IndexOnlyScanState *) node);
283+
break;
284+
276285
case T_TidScanState:
277286
ExecTidMarkPos((TidScanState *) node);
278287
break;
@@ -326,6 +335,10 @@ ExecRestrPos(PlanState *node)
326335
ExecIndexRestrPos((IndexScanState *) node);
327336
break;
328337

338+
case T_IndexOnlyScanState:
339+
ExecIndexOnlyRestrPos((IndexOnlyScanState *) node);
340+
break;
341+
329342
case T_TidScanState:
330343
ExecTidRestrPos((TidScanState *) node);
331344
break;
@@ -371,6 +384,7 @@ ExecSupportsMarkRestore(NodeTag plantype)
371384
{
372385
case T_SeqScan:
373386
case T_IndexScan:
387+
case T_IndexOnlyScan:
374388
case T_TidScan:
375389
case T_ValuesScan:
376390
case T_Material:
@@ -442,6 +456,10 @@ ExecSupportsBackwardScan(Plan *node)
442456
return IndexSupportsBackwardScan(((IndexScan *) node)->indexid) &&
443457
TargetListSupportsBackwardScan(node->targetlist);
444458

459+
case T_IndexOnlyScan:
460+
return IndexSupportsBackwardScan(((IndexOnlyScan *) node)->indexid) &&
461+
TargetListSupportsBackwardScan(node->targetlist);
462+
445463
case T_SubqueryScan:
446464
return ExecSupportsBackwardScan(((SubqueryScan *) node)->subplan) &&
447465
TargetListSupportsBackwardScan(node->targetlist);
@@ -474,7 +492,8 @@ TargetListSupportsBackwardScan(List *targetlist)
474492
}
475493

476494
/*
477-
* An IndexScan node supports backward scan only if the index's AM does.
495+
* An IndexScan or IndexOnlyScan node supports backward scan only if the
496+
* index's AM does.
478497
*/
479498
static bool
480499
IndexSupportsBackwardScan(Oid indexid)

‎src/backend/executor/execCurrent.c

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -262,6 +262,7 @@ search_plan_tree(PlanState *node, Oid table_oid)
262262
*/
263263
case T_SeqScanState:
264264
case T_IndexScanState:
265+
case T_IndexOnlyScanState:
265266
case T_BitmapHeapScanState:
266267
case T_TidScanState:
267268
{

‎src/backend/executor/execProcnode.c

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -89,6 +89,7 @@
8989
#include "executor/nodeGroup.h"
9090
#include "executor/nodeHash.h"
9191
#include "executor/nodeHashjoin.h"
92+
#include "executor/nodeIndexonlyscan.h"
9293
#include "executor/nodeIndexscan.h"
9394
#include "executor/nodeLimit.h"
9495
#include "executor/nodeLockRows.h"
@@ -192,6 +193,11 @@ ExecInitNode(Plan *node, EState *estate, int eflags)
192193
estate, eflags);
193194
break;
194195

196+
case T_IndexOnlyScan:
197+
result = (PlanState *) ExecInitIndexOnlyScan((IndexOnlyScan *) node,
198+
estate, eflags);
199+
break;
200+
195201
case T_BitmapIndexScan:
196202
result = (PlanState *) ExecInitBitmapIndexScan((BitmapIndexScan *) node,
197203
estate, eflags);
@@ -397,6 +403,10 @@ ExecProcNode(PlanState *node)
397403
result = ExecIndexScan((IndexScanState *) node);
398404
break;
399405

406+
case T_IndexOnlyScanState:
407+
result = ExecIndexOnlyScan((IndexOnlyScanState *) node);
408+
break;
409+
400410
/* BitmapIndexScanState does not yield tuples */
401411

402412
case T_BitmapHeapScanState:
@@ -627,6 +637,10 @@ ExecEndNode(PlanState *node)
627637
ExecEndIndexScan((IndexScanState *) node);
628638
break;
629639

640+
case T_IndexOnlyScanState:
641+
ExecEndIndexOnlyScan((IndexOnlyScanState *) node);
642+
break;
643+
630644
case T_BitmapIndexScanState:
631645
ExecEndBitmapIndexScan((BitmapIndexScanState *) node);
632646
break;

‎src/backend/executor/execQual.c

Lines changed: 16 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -578,14 +578,16 @@ ExecEvalVar(ExprState *exprstate, ExprContext *econtext,
578578
/* Get the input slot and attribute number we want */
579579
switch (variable->varno)
580580
{
581-
case INNER: /* get the tuple from the inner node */
581+
case INNER_VAR: /* get the tuple from the inner node */
582582
slot = econtext->ecxt_innertuple;
583583
break;
584584

585-
case OUTER: /* get the tuple from the outer node */
585+
case OUTER_VAR: /* get the tuple from the outer node */
586586
slot = econtext->ecxt_outertuple;
587587
break;
588588

589+
/* INDEX_VAR is handled by default case */
590+
589591
default: /* get the tuple from the relation being
590592
* scanned */
591593
slot = econtext->ecxt_scantuple;
@@ -761,14 +763,16 @@ ExecEvalScalarVar(ExprState *exprstate, ExprContext *econtext,
761763
/* Get the input slot and attribute number we want */
762764
switch (variable->varno)
763765
{
764-
case INNER: /* get the tuple from the inner node */
766+
case INNER_VAR: /* get the tuple from the inner node */
765767
slot = econtext->ecxt_innertuple;
766768
break;
767769

768-
case OUTER: /* get the tuple from the outer node */
770+
case OUTER_VAR: /* get the tuple from the outer node */
769771
slot = econtext->ecxt_outertuple;
770772
break;
771773

774+
/* INDEX_VAR is handled by default case */
775+
772776
default: /* get the tuple from the relation being
773777
* scanned */
774778
slot = econtext->ecxt_scantuple;
@@ -804,14 +808,16 @@ ExecEvalWholeRowVar(ExprState *exprstate, ExprContext *econtext,
804808
/* Get the input slot we want */
805809
switch (variable->varno)
806810
{
807-
case INNER: /* get the tuple from the inner node */
811+
case INNER_VAR: /* get the tuple from the inner node */
808812
slot = econtext->ecxt_innertuple;
809813
break;
810814

811-
case OUTER: /* get the tuple from the outer node */
815+
case OUTER_VAR: /* get the tuple from the outer node */
812816
slot = econtext->ecxt_outertuple;
813817
break;
814818

819+
/* INDEX_VAR is handled by default case */
820+
815821
default: /* get the tuple from the relation being
816822
* scanned */
817823
slot = econtext->ecxt_scantuple;
@@ -873,14 +879,16 @@ ExecEvalWholeRowSlow(ExprState *exprstate, ExprContext *econtext,
873879
/* Get the input slot we want */
874880
switch (variable->varno)
875881
{
876-
case INNER: /* get the tuple from the inner node */
882+
case INNER_VAR: /* get the tuple from the inner node */
877883
slot = econtext->ecxt_innertuple;
878884
break;
879885

880-
case OUTER: /* get the tuple from the outer node */
886+
case OUTER_VAR: /* get the tuple from the outer node */
881887
slot = econtext->ecxt_outertuple;
882888
break;
883889

890+
/* INDEX_VAR is handled by default case */
891+
884892
default: /* get the tuple from the relation being
885893
* scanned */
886894
slot = econtext->ecxt_scantuple;

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