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Commita9b05bd

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committed
Avoid O(N^2) overhead in repeated nocachegetattr calls when columns of
a tuple are being accessed via ExecEvalVar and the attcacheoff shortcutisn't usable (due to nulls and/or varlena columns). To do this, cacheDatums extracted from a tuple in the associated TupleTableSlot.Also some code cleanup in and around the TupleTable handling.Atsushi Ogawa with some kibitzing by Tom Lane.
1 parentd1022ce commita9b05bd

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8 files changed

+361
-283
lines changed

8 files changed

+361
-283
lines changed

‎src/backend/access/common/heaptuple.c‎

Lines changed: 184 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
*
1010
*
1111
* IDENTIFICATION
12-
* $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.96 2005/01/27 23:23:49 neilc Exp $
12+
* $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.97 2005/03/14 04:41:12 tgl Exp $
1313
*
1414
* NOTES
1515
* The old interface functions have been converted to macros
@@ -23,6 +23,7 @@
2323
#include"access/heapam.h"
2424
#include"access/tuptoaster.h"
2525
#include"catalog/pg_type.h"
26+
#include"executor/tuptable.h"
2627

2728

2829
/* ----------------------------------------------------------------
@@ -751,6 +752,7 @@ heap_deformtuple(HeapTuple tuple,
751752
char*nulls)
752753
{
753754
HeapTupleHeadertup=tuple->t_data;
755+
boolhasnulls=HeapTupleHasNulls(tuple);
754756
Form_pg_attribute*att=tupleDesc->attrs;
755757
inttdesc_natts=tupleDesc->natts;
756758
intnatts;/* number of atts to extract */
@@ -775,7 +777,9 @@ heap_deformtuple(HeapTuple tuple,
775777

776778
for (attnum=0;attnum<natts;attnum++)
777779
{
778-
if (HeapTupleHasNulls(tuple)&&att_isnull(attnum,bp))
780+
Form_pg_attributethisatt=att[attnum];
781+
782+
if (hasnulls&&att_isnull(attnum,bp))
779783
{
780784
values[attnum]= (Datum)0;
781785
nulls[attnum]='n';
@@ -785,21 +789,21 @@ heap_deformtuple(HeapTuple tuple,
785789

786790
nulls[attnum]=' ';
787791

788-
if (!slow&&att[attnum]->attcacheoff >=0)
789-
off=att[attnum]->attcacheoff;
792+
if (!slow&&thisatt->attcacheoff >=0)
793+
off=thisatt->attcacheoff;
790794
else
791795
{
792-
off=att_align(off,att[attnum]->attalign);
796+
off=att_align(off,thisatt->attalign);
793797

794798
if (!slow)
795-
att[attnum]->attcacheoff=off;
799+
thisatt->attcacheoff=off;
796800
}
797801

798-
values[attnum]=fetchatt(att[attnum],tp+off);
802+
values[attnum]=fetchatt(thisatt,tp+off);
799803

800-
off=att_addlength(off,att[attnum]->attlen,tp+off);
804+
off=att_addlength(off,thisatt->attlen,tp+off);
801805

802-
if (att[attnum]->attlen <=0)
806+
if (thisatt->attlen <=0)
803807
slow= true;/* can't use attcacheoff anymore */
804808
}
805809

@@ -814,6 +818,177 @@ heap_deformtuple(HeapTuple tuple,
814818
}
815819
}
816820

821+
/* ----------------
822+
*slot_deformtuple
823+
*
824+
*Given a TupleTableSlot, extract data into cache_values array
825+
*from the slot's tuple.
826+
*
827+
*This is essentially an incremental version of heap_deformtuple:
828+
*on each call we extract attributes up to the one needed, without
829+
*re-computing information about previously extracted attributes.
830+
*slot->cache_natts is the number of attributes already extracted.
831+
*
832+
*This only gets called from slot_getattr. Note that slot_getattr
833+
*must check for a null attribute since we don't create an array
834+
*of null indicators.
835+
* ----------------
836+
*/
837+
staticvoid
838+
slot_deformtuple(TupleTableSlot*slot,intnatts)
839+
{
840+
HeapTupletuple=slot->val;
841+
TupleDesctupleDesc=slot->ttc_tupleDescriptor;
842+
Datum*values=slot->cache_values;
843+
HeapTupleHeadertup=tuple->t_data;
844+
boolhasnulls=HeapTupleHasNulls(tuple);
845+
Form_pg_attribute*att=tupleDesc->attrs;
846+
intattnum;
847+
char*tp;/* ptr to tuple data */
848+
longoff;/* offset in tuple data */
849+
bits8*bp=tup->t_bits;/* ptr to null bitmask in tuple */
850+
boolslow;/* can we use/set attcacheoff? */
851+
852+
/*
853+
* Check whether the first call for this tuple, and initialize or
854+
* restore loop state.
855+
*/
856+
attnum=slot->cache_natts;
857+
if (attnum==0)
858+
{
859+
/* Start from the first attribute */
860+
off=0;
861+
slow= false;
862+
}
863+
else
864+
{
865+
/* Restore state from previous execution */
866+
off=slot->cache_off;
867+
slow=slot->cache_slow;
868+
}
869+
870+
tp= (char*)tup+tup->t_hoff;
871+
872+
for (;attnum<natts;attnum++)
873+
{
874+
Form_pg_attributethisatt=att[attnum];
875+
876+
if (hasnulls&&att_isnull(attnum,bp))
877+
{
878+
values[attnum]= (Datum)0;
879+
slow= true;/* can't use attcacheoff anymore */
880+
continue;
881+
}
882+
883+
if (!slow&&thisatt->attcacheoff >=0)
884+
off=thisatt->attcacheoff;
885+
else
886+
{
887+
off=att_align(off,thisatt->attalign);
888+
889+
if (!slow)
890+
thisatt->attcacheoff=off;
891+
}
892+
893+
values[attnum]=fetchatt(thisatt,tp+off);
894+
895+
off=att_addlength(off,thisatt->attlen,tp+off);
896+
897+
if (thisatt->attlen <=0)
898+
slow= true;/* can't use attcacheoff anymore */
899+
}
900+
901+
/*
902+
* Save state for next execution
903+
*/
904+
slot->cache_natts=attnum;
905+
slot->cache_off=off;
906+
slot->cache_slow=slow;
907+
}
908+
909+
/* --------------------------------
910+
*slot_getattr
911+
*
912+
*This function fetches an attribute of the slot's current tuple.
913+
*It is functionally equivalent to heap_getattr, but fetches of
914+
*multiple attributes of the same tuple will be optimized better,
915+
*because we avoid O(N^2) behavior from multiple calls of
916+
*nocachegetattr(), even when attcacheoff isn't usable.
917+
* --------------------------------
918+
*/
919+
Datum
920+
slot_getattr(TupleTableSlot*slot,intattnum,bool*isnull)
921+
{
922+
HeapTupletuple=slot->val;
923+
TupleDesctupleDesc=slot->ttc_tupleDescriptor;
924+
HeapTupleHeadertup;
925+
926+
/*
927+
* system attributes are handled by heap_getsysattr
928+
*/
929+
if (attnum <=0)
930+
returnheap_getsysattr(tuple,attnum,tupleDesc,isnull);
931+
932+
/*
933+
* check if attnum is out of range according to either the tupdesc
934+
* or the tuple itself; if so return NULL
935+
*/
936+
tup=tuple->t_data;
937+
938+
if (attnum>tup->t_natts||attnum>tupleDesc->natts)
939+
{
940+
*isnull= true;
941+
return (Datum)0;
942+
}
943+
944+
/*
945+
* check if target attribute is null
946+
*/
947+
if (HeapTupleHasNulls(tuple)&&att_isnull(attnum-1,tup->t_bits))
948+
{
949+
*isnull= true;
950+
return (Datum)0;
951+
}
952+
953+
/*
954+
* If the attribute's column has been dropped, we force a NULL
955+
* result. This case should not happen in normal use, but it could
956+
* happen if we are executing a plan cached before the column was
957+
* dropped.
958+
*/
959+
if (tupleDesc->attrs[attnum-1]->attisdropped)
960+
{
961+
*isnull= true;
962+
return (Datum)0;
963+
}
964+
965+
/*
966+
* If attribute wasn't already extracted, extract it and preceding
967+
* attributes.
968+
*/
969+
if (attnum>slot->cache_natts)
970+
{
971+
/*
972+
* If first time for this TupleTableSlot, allocate the cache
973+
* workspace. It must have the same lifetime as the slot, so allocate
974+
* it in the slot's own context. We size the array according to what
975+
* the tupdesc says, NOT the tuple.
976+
*/
977+
if (slot->cache_values==NULL)
978+
slot->cache_values= (Datum*)
979+
MemoryContextAlloc(slot->ttc_mcxt,
980+
tupleDesc->natts*sizeof(Datum));
981+
982+
slot_deformtuple(slot,attnum);
983+
}
984+
985+
/*
986+
* The result is acquired from cache_values array.
987+
*/
988+
*isnull= false;
989+
returnslot->cache_values[attnum-1];
990+
}
991+
817992
/* ----------------
818993
*heap_freetuple
819994
* ----------------

‎src/backend/access/heap/tuptoaster.c‎

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.47 2005/01/01 05:43:06 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.48 2005/03/14 04:41:12 tgl Exp $
1212
*
1313
*
1414
* INTERFACE ROUTINES
@@ -1197,9 +1197,9 @@ toast_fetch_datum(varattrib *attr)
11971197
/*
11981198
* Have a chunk, extract the sequence number and the data
11991199
*/
1200-
residx=DatumGetInt32(heap_getattr(ttup,2,toasttupDesc,&isnull));
1200+
residx=DatumGetInt32(fastgetattr(ttup,2,toasttupDesc,&isnull));
12011201
Assert(!isnull);
1202-
chunk=DatumGetPointer(heap_getattr(ttup,3,toasttupDesc,&isnull));
1202+
chunk=DatumGetPointer(fastgetattr(ttup,3,toasttupDesc,&isnull));
12031203
Assert(!isnull);
12041204
chunksize=VARATT_SIZE(chunk)-VARHDRSZ;
12051205

@@ -1372,9 +1372,9 @@ toast_fetch_datum_slice(varattrib *attr, int32 sliceoffset, int32 length)
13721372
/*
13731373
* Have a chunk, extract the sequence number and the data
13741374
*/
1375-
residx=DatumGetInt32(heap_getattr(ttup,2,toasttupDesc,&isnull));
1375+
residx=DatumGetInt32(fastgetattr(ttup,2,toasttupDesc,&isnull));
13761376
Assert(!isnull);
1377-
chunk=DatumGetPointer(heap_getattr(ttup,3,toasttupDesc,&isnull));
1377+
chunk=DatumGetPointer(fastgetattr(ttup,3,toasttupDesc,&isnull));
13781378
Assert(!isnull);
13791379
chunksize=VARATT_SIZE(chunk)-VARHDRSZ;
13801380

‎src/backend/executor/execJunk.c‎

Lines changed: 7 additions & 27 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/executor/execJunk.c,v 1.46 2004/12/31 21:59:45 pgsql Exp $
11+
* $PostgreSQL: pgsql/src/backend/executor/execJunk.c,v 1.47 2005/03/14 04:41:12 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -209,20 +209,13 @@ ExecGetJunkAttribute(JunkFilter *junkfilter,
209209
Datum*value,
210210
bool*isNull)
211211
{
212-
List*targetList;
213212
ListCell*t;
214-
AttrNumberresno;
215-
TupleDesctupType;
216-
HeapTupletuple;
217213

218214
/*
219-
*first look in the junkfilter's target list for an attribute with
215+
*Look in the junkfilter's target list for an attribute with
220216
* the given name
221217
*/
222-
resno=InvalidAttrNumber;
223-
targetList=junkfilter->jf_targetList;
224-
225-
foreach(t,targetList)
218+
foreach(t,junkfilter->jf_targetList)
226219
{
227220
TargetEntry*tle=lfirst(t);
228221
Resdom*resdom=tle->resdom;
@@ -231,26 +224,13 @@ ExecGetJunkAttribute(JunkFilter *junkfilter,
231224
(strcmp(resdom->resname,attrName)==0))
232225
{
233226
/* We found it ! */
234-
resno=resdom->resno;
235-
break;
227+
*value=slot_getattr(slot,resdom->resno,isNull);
228+
return true;
236229
}
237230
}
238231

239-
if (resno==InvalidAttrNumber)
240-
{
241-
/* Ooops! We couldn't find this attribute... */
242-
return false;
243-
}
244-
245-
/*
246-
* Now extract the attribute value from the tuple.
247-
*/
248-
tuple=slot->val;
249-
tupType=slot->ttc_tupleDescriptor;
250-
251-
*value=heap_getattr(tuple,resno,tupType,isNull);
252-
253-
return true;
232+
/* Ooops! We couldn't find this attribute... */
233+
return false;
254234
}
255235

256236
/*

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