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Commitd25367e

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Add bms_get_singleton_member(), and use it where appropriate.
This patch adds a function that replaces a bms_membership() test followedby a bms_singleton_member() call, performing both the test and theextraction of a singleton set's member in one scan of the bitmapset.The performance advantage over the old way is probably minimal in currentusage, but it seems worthwhile on notational grounds anyway.David Rowley
1 parentf4e031c commitd25367e

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5 files changed

+52
-7
lines changed

5 files changed

+52
-7
lines changed

‎src/backend/nodes/bitmapset.c

Lines changed: 44 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -524,6 +524,50 @@ bms_singleton_member(const Bitmapset *a)
524524
returnresult;
525525
}
526526

527+
/*
528+
* bms_get_singleton_member
529+
*
530+
* Test whether the given set is a singleton.
531+
* If so, set *member to the value of its sole member, and return TRUE.
532+
* If not, return FALSE, without changing *member.
533+
*
534+
* This is more convenient and faster than calling bms_membership() and then
535+
* bms_singleton_member(), if we don't care about distinguishing empty sets
536+
* from multiple-member sets.
537+
*/
538+
bool
539+
bms_get_singleton_member(constBitmapset*a,int*member)
540+
{
541+
intresult=-1;
542+
intnwords;
543+
intwordnum;
544+
545+
if (a==NULL)
546+
return false;
547+
nwords=a->nwords;
548+
for (wordnum=0;wordnum<nwords;wordnum++)
549+
{
550+
bitmapwordw=a->words[wordnum];
551+
552+
if (w!=0)
553+
{
554+
if (result >=0||HAS_MULTIPLE_ONES(w))
555+
return false;
556+
result=wordnum*BITS_PER_BITMAPWORD;
557+
while ((w&255)==0)
558+
{
559+
w >>=8;
560+
result+=8;
561+
}
562+
result+=rightmost_one_pos[w&255];
563+
}
564+
}
565+
if (result<0)
566+
return false;
567+
*member=result;
568+
return true;
569+
}
570+
527571
/*
528572
* bms_num_members - count members of set
529573
*/

‎src/backend/optimizer/path/equivclass.c

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -867,9 +867,8 @@ generate_base_implied_equalities_no_const(PlannerInfo *root,
867867
intrelid;
868868

869869
Assert(!cur_em->em_is_child);/* no children yet */
870-
if (bms_membership(cur_em->em_relids)!=BMS_SINGLETON)
870+
if (!bms_get_singleton_member(cur_em->em_relids,&relid))
871871
continue;
872-
relid=bms_singleton_member(cur_em->em_relids);
873872
Assert(relid<root->simple_rel_array_size);
874873

875874
if (prev_ems[relid]!=NULL)

‎src/backend/optimizer/plan/analyzejoins.c

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -162,11 +162,12 @@ join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo)
162162
* going to be able to do anything with it.
163163
*/
164164
if (sjinfo->jointype!=JOIN_LEFT||
165-
sjinfo->delay_upper_joins||
166-
bms_membership(sjinfo->min_righthand)!=BMS_SINGLETON)
165+
sjinfo->delay_upper_joins)
166+
return false;
167+
168+
if (!bms_get_singleton_member(sjinfo->min_righthand,&innerrelid))
167169
return false;
168170

169-
innerrelid=bms_singleton_member(sjinfo->min_righthand);
170171
innerrel=find_base_rel(root,innerrelid);
171172

172173
if (innerrel->reloptkind!=RELOPT_BASEREL)

‎src/backend/optimizer/util/placeholder.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -383,10 +383,10 @@ add_placeholders_to_base_rels(PlannerInfo *root)
383383
{
384384
PlaceHolderInfo*phinfo= (PlaceHolderInfo*)lfirst(lc);
385385
Relidseval_at=phinfo->ph_eval_at;
386+
intvarno;
386387

387-
if (bms_membership(eval_at)==BMS_SINGLETON)
388+
if (bms_get_singleton_member(eval_at,&varno))
388389
{
389-
intvarno=bms_singleton_member(eval_at);
390390
RelOptInfo*rel=find_base_rel(root,varno);
391391

392392
/* add it to reltargetlist if needed above the rel scan level */

‎src/include/nodes/bitmapset.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -72,6 +72,7 @@ extern bool bms_is_member(int x, const Bitmapset *a);
7272
externboolbms_overlap(constBitmapset*a,constBitmapset*b);
7373
externboolbms_nonempty_difference(constBitmapset*a,constBitmapset*b);
7474
externintbms_singleton_member(constBitmapset*a);
75+
externboolbms_get_singleton_member(constBitmapset*a,int*member);
7576
externintbms_num_members(constBitmapset*a);
7677

7778
/* optimized tests when we don't need to know exact membership count: */

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