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Commit29c4ad9

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Support "x IS NOT NULL" clauses as indexscan conditions. This turns out
to be just a minor extension of the previous patch that made "x IS NULL"indexable, because we can treat the IS NOT NULL condition as if it were"x < NULL" or "x > NULL" (depending on the index's NULLS FIRST/LAST option),just like IS NULL is treated like "x = NULL". Aside from any possibleusefulness in its own right, this is an important improvement forindex-optimized MAX/MIN aggregates: it is now reliably possible to geta column's min or max value cheaply, even when there are a lot of nullscluttering the interesting end of the index.
1 parent15faca2 commit29c4ad9

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18 files changed

+295
-120
lines changed

18 files changed

+295
-120
lines changed

‎doc/src/sgml/catalogs.sgml

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.215 2009/12/29 20:11:42 tgl Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.216 2010/01/01 21:53:48 tgl Exp $ -->
22
<!--
33
Documentation of the system catalogs, directed toward PostgreSQL developers
44
-->
@@ -466,7 +466,7 @@
466466
<entry><structfield>amsearchnulls</structfield></entry>
467467
<entry><type>bool</type></entry>
468468
<entry></entry>
469-
<entry>Does the access method support IS NULL searches?</entry>
469+
<entry>Does the access method support IS NULL/NOT NULL searches?</entry>
470470
</row>
471471

472472
<row>

‎doc/src/sgml/indexam.sgml

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.31 2009/07/29 20:56:17 tgl Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.32 2010/01/01 21:53:49 tgl Exp $ -->
22

33
<chapter id="indexam">
44
<title>Index Access Method Interface Definition</title>
@@ -134,7 +134,8 @@
134134
null values. An index access method that sets
135135
<structfield>amindexnulls</structfield> may also set
136136
<structfield>amsearchnulls</structfield>, indicating that it supports
137-
<literal>IS NULL</> clauses as search conditions.
137+
<literal>IS NULL</> and <literal>IS NOT NULL</> clauses as search
138+
conditions.
138139
</para>
139140

140141
</sect1>

‎doc/src/sgml/indices.sgml

Lines changed: 5 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/indices.sgml,v 1.79 2009/08/07 20:54:31 alvherre Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/indices.sgml,v 1.80 2010/01/01 21:53:49 tgl Exp $ -->
22

33
<chapter id="indexes">
44
<title id="indexes-title">Indexes</title>
@@ -147,8 +147,8 @@ CREATE INDEX test1_id_index ON test1 (id);
147147

148148
Constructs equivalent to combinations of these operators, such as
149149
<literal>BETWEEN</> and <literal>IN</>, can also be implemented with
150-
a B-tree index search. Also, an <literal>IS NULL</>condition on
151-
an index column can be used with a B-tree index.
150+
a B-tree index search. Also, an <literal>IS NULL</>or <literal>IS NOT
151+
NULL</> condition onan index column can be used with a B-tree index.
152152
</para>
153153

154154
<para>
@@ -180,8 +180,7 @@ CREATE INDEX test1_id_index ON test1 (id);
180180
Hash indexes can only handle simple equality comparisons.
181181
The query planner will consider using a hash index whenever an
182182
indexed column is involved in a comparison using the
183-
<literal>=</literal> operator. (Hash indexes do not support
184-
<literal>IS NULL</> searches.)
183+
<literal>=</literal> operator.
185184
The following command is used to create a hash index:
186185
<synopsis>
187186
CREATE INDEX <replaceable>name</replaceable> ON <replaceable>table</replaceable> USING hash (<replaceable>column</replaceable>);
@@ -1025,7 +1024,7 @@ SELECT am.amname AS index_method,
10251024
real statistics, some default values are assumed, which are
10261025
almost certain to be inaccurate. Examining an application's
10271026
index usage without having run <command>ANALYZE</command> is
1028-
therefore a lost cause.
1027+
therefore a lost cause.
10291028
See <xref linkend="vacuum-for-statistics" endterm="vacuum-for-statistics-title">
10301029
and <xref linkend="autovacuum" endterm="autovacuum-title"> for more information.
10311030
</para>

‎src/backend/access/common/scankey.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/common/scankey.c,v 1.32 2009/01/0117:23:34 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/common/scankey.c,v 1.33 2010/01/0121:53:49 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -21,7 +21,7 @@
2121
* ScanKeyEntryInitialize
2222
*Initializes a scan key entry given all the field values.
2323
*The target procedure is specified by OID (but can be invalid
24-
*if SK_SEARCHNULL is set).
24+
*if SK_SEARCHNULLor SK_SEARCHNOTNULLis set).
2525
*
2626
* Note: CurrentMemoryContext at call should be as long-lived as the ScanKey
2727
* itself, because that's what will be used for any subsidiary info attached
@@ -45,7 +45,7 @@ ScanKeyEntryInitialize(ScanKey entry,
4545
fmgr_info(procedure,&entry->sk_func);
4646
else
4747
{
48-
Assert(flags&SK_SEARCHNULL);
48+
Assert(flags&(SK_SEARCHNULL |SK_SEARCHNOTNULL));
4949
MemSet(&entry->sk_func,0,sizeof(entry->sk_func));
5050
}
5151
}

‎src/backend/access/gist/gistget.c

Lines changed: 14 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.82 2009/10/08 22:34:57 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.83 2010/01/01 21:53:49 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -413,14 +413,20 @@ gistindex_keytest(IndexTuple tuple,
413413
{
414414
/*
415415
* On non-leaf page we can't conclude that child hasn't NULL
416-
* values because of assumption in GiST:uinon (VAL, NULL) is VAL
417-
* But if on non-leaf page key ISNULL then allchilds has NULL.
416+
* values because of assumption in GiST:union (VAL, NULL) is VAL.
417+
* But if on non-leaf page key IS NULL, then allchildren are NULL.
418418
*/
419-
420-
Assert(key->sk_flags&SK_SEARCHNULL);
421-
422-
if (GistPageIsLeaf(p)&& !isNull)
423-
return false;
419+
if (key->sk_flags&SK_SEARCHNULL)
420+
{
421+
if (GistPageIsLeaf(p)&& !isNull)
422+
return false;
423+
}
424+
else
425+
{
426+
Assert(key->sk_flags&SK_SEARCHNOTNULL);
427+
if (isNull)
428+
return false;
429+
}
424430
}
425431
elseif (isNull)
426432
{

‎src/backend/access/gist/gistscan.c

Lines changed: 8 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.76 2009/06/11 14:48:53 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.77 2010/01/01 21:53:49 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -92,15 +92,18 @@ gistrescan(PG_FUNCTION_ARGS)
9292
* field.
9393
*
9494
* Next, if any of keys is a NULL and that key is not marked with
95-
* SK_SEARCHNULL then nothing can be found.
95+
* SK_SEARCHNULL/SK_SEARCHNOTNULL then nothing can be found (ie,
96+
* we assume all indexable operators are strict).
9697
*/
9798
for (i=0;i<scan->numberOfKeys;i++)
9899
{
99-
scan->keyData[i].sk_func=so->giststate->consistentFn[scan->keyData[i].sk_attno-1];
100+
ScanKeyskey=&(scan->keyData[i]);
100101

101-
if (scan->keyData[i].sk_flags&SK_ISNULL)
102+
skey->sk_func=so->giststate->consistentFn[skey->sk_attno-1];
103+
104+
if (skey->sk_flags&SK_ISNULL)
102105
{
103-
if ((scan->keyData[i].sk_flags&SK_SEARCHNULL)==0)
106+
if (!(skey->sk_flags&(SK_SEARCHNULL |SK_SEARCHNOTNULL)))
104107
so->qual_ok= false;
105108
}
106109
}

‎src/backend/access/nbtree/nbtutils.c

Lines changed: 109 additions & 35 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtutils.c,v 1.94 2009/10/08 22:34:57 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtutils.c,v 1.95 2010/01/01 21:53:49 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -276,6 +276,11 @@ _bt_preprocess_keys(IndexScanDesc scan)
276276
* in any particular strategy in this case, so set it to
277277
* BTEqualStrategyNumber --- we can treat IS NULL as an equality
278278
* operator for purposes of search strategy.
279+
*
280+
* Likewise, "x IS NOT NULL" is supported. We treat that as either
281+
* "less than NULL" in a NULLS LAST index, or "greater than NULL"
282+
* in a NULLS FIRST index. However, we have to flip those around in
283+
* a DESC index, to allow for the re-flipping that occurs elsewhere.
279284
*/
280285
if (cur->sk_flags&SK_ISNULL)
281286
{
@@ -284,6 +289,21 @@ _bt_preprocess_keys(IndexScanDesc scan)
284289
cur->sk_strategy=BTEqualStrategyNumber;
285290
cur->sk_subtype=InvalidOid;
286291
}
292+
elseif (cur->sk_flags&SK_SEARCHNOTNULL)
293+
{
294+
switch (indoption[cur->sk_attno-1]&
295+
(INDOPTION_DESC |INDOPTION_NULLS_FIRST))
296+
{
297+
case0:/* ASC / NULLS LAST */
298+
caseINDOPTION_DESC |INDOPTION_NULLS_FIRST:
299+
cur->sk_strategy=BTLessStrategyNumber;
300+
break;
301+
default:
302+
cur->sk_strategy=BTGreaterStrategyNumber;
303+
break;
304+
}
305+
cur->sk_subtype=InvalidOid;
306+
}
287307
else
288308
so->qual_ok= false;
289309
}
@@ -320,7 +340,7 @@ _bt_preprocess_keys(IndexScanDesc scan)
320340
{
321341
if (i<numberOfKeys)
322342
{
323-
/* See comments above about NULLs and IS NULLhandling. */
343+
/* See comments above about NULLs and IS NULL/NOT NULLhandling */
324344
/* Note: we assume SK_ISNULL is never set in a row header key */
325345
if (cur->sk_flags&SK_ISNULL)
326346
{
@@ -329,6 +349,21 @@ _bt_preprocess_keys(IndexScanDesc scan)
329349
cur->sk_strategy=BTEqualStrategyNumber;
330350
cur->sk_subtype=InvalidOid;
331351
}
352+
elseif (cur->sk_flags&SK_SEARCHNOTNULL)
353+
{
354+
switch (indoption[cur->sk_attno-1]&
355+
(INDOPTION_DESC |INDOPTION_NULLS_FIRST))
356+
{
357+
case0:/* ASC / NULLS LAST */
358+
caseINDOPTION_DESC |INDOPTION_NULLS_FIRST:
359+
cur->sk_strategy=BTLessStrategyNumber;
360+
break;
361+
default:
362+
cur->sk_strategy=BTGreaterStrategyNumber;
363+
break;
364+
}
365+
cur->sk_subtype=InvalidOid;
366+
}
332367
else
333368
{
334369
so->qual_ok= false;
@@ -365,13 +400,6 @@ _bt_preprocess_keys(IndexScanDesc scan)
365400
if (!chk||j== (BTEqualStrategyNumber-1))
366401
continue;
367402

368-
/* IS NULL together with any other predicate must fail */
369-
if (eq->sk_flags&SK_SEARCHNULL)
370-
{
371-
so->qual_ok= false;
372-
return;
373-
}
374-
375403
if (_bt_compare_scankey_args(scan,chk,eq,chk,
376404
&test_result))
377405
{
@@ -484,23 +512,6 @@ _bt_preprocess_keys(IndexScanDesc scan)
484512
else
485513
{
486514
/* yup, keep only the more restrictive key */
487-
488-
/* if either arg is NULL, don't try to compare */
489-
if ((cur->sk_flags |xform[j]->sk_flags)&SK_ISNULL)
490-
{
491-
/* at least one of them must be an IS NULL clause */
492-
Assert(j== (BTEqualStrategyNumber-1));
493-
Assert((cur->sk_flags |xform[j]->sk_flags)&SK_SEARCHNULL);
494-
/* if one is and one isn't, the search must fail */
495-
if ((cur->sk_flags ^xform[j]->sk_flags)&SK_SEARCHNULL)
496-
{
497-
so->qual_ok= false;
498-
return;
499-
}
500-
/* we have duplicate IS NULL clauses, ignore the newer one */
501-
continue;
502-
}
503-
504515
if (_bt_compare_scankey_args(scan,cur,cur,xform[j],
505516
&test_result))
506517
{
@@ -534,8 +545,7 @@ _bt_preprocess_keys(IndexScanDesc scan)
534545
}
535546

536547
/*
537-
* Compare two scankey values using a specified operator. Both values
538-
* must be already known non-NULL.
548+
* Compare two scankey values using a specified operator.
539549
*
540550
* The test we want to perform is logically "leftarg op rightarg", where
541551
* leftarg and rightarg are the sk_argument values in those ScanKeys, and
@@ -555,8 +565,7 @@ _bt_preprocess_keys(IndexScanDesc scan)
555565
*
556566
* Note: this routine needs to be insensitive to any DESC option applied
557567
* to the index column. For example, "x < 4" is a tighter constraint than
558-
* "x < 5" regardless of which way the index is sorted. We don't worry about
559-
* NULLS FIRST/LAST either, since the given values are never nulls.
568+
* "x < 5" regardless of which way the index is sorted.
560569
*/
561570
staticbool
562571
_bt_compare_scankey_args(IndexScanDescscan,ScanKeyop,
@@ -571,6 +580,64 @@ _bt_compare_scankey_args(IndexScanDesc scan, ScanKey op,
571580
cmp_op;
572581
StrategyNumberstrat;
573582

583+
/*
584+
* First, deal with cases where one or both args are NULL. This should
585+
* only happen when the scankeys represent IS NULL/NOT NULL conditions.
586+
*/
587+
if ((leftarg->sk_flags |rightarg->sk_flags)&SK_ISNULL)
588+
{
589+
boolleftnull,
590+
rightnull;
591+
592+
if (leftarg->sk_flags&SK_ISNULL)
593+
{
594+
Assert(leftarg->sk_flags& (SK_SEARCHNULL |SK_SEARCHNOTNULL));
595+
leftnull= true;
596+
}
597+
else
598+
leftnull= false;
599+
if (rightarg->sk_flags&SK_ISNULL)
600+
{
601+
Assert(rightarg->sk_flags& (SK_SEARCHNULL |SK_SEARCHNOTNULL));
602+
rightnull= true;
603+
}
604+
else
605+
rightnull= false;
606+
607+
/*
608+
* We treat NULL as either greater than or less than all other values.
609+
* Since true > false, the tests below work correctly for NULLS LAST
610+
* logic. If the index is NULLS FIRST, we need to flip the strategy.
611+
*/
612+
strat=op->sk_strategy;
613+
if (op->sk_flags&SK_BT_NULLS_FIRST)
614+
strat=BTCommuteStrategyNumber(strat);
615+
616+
switch (strat)
617+
{
618+
caseBTLessStrategyNumber:
619+
*result= (leftnull<rightnull);
620+
break;
621+
caseBTLessEqualStrategyNumber:
622+
*result= (leftnull <=rightnull);
623+
break;
624+
caseBTEqualStrategyNumber:
625+
*result= (leftnull==rightnull);
626+
break;
627+
caseBTGreaterEqualStrategyNumber:
628+
*result= (leftnull >=rightnull);
629+
break;
630+
caseBTGreaterStrategyNumber:
631+
*result= (leftnull>rightnull);
632+
break;
633+
default:
634+
elog(ERROR,"unrecognized StrategyNumber: %d", (int)strat);
635+
*result= false;/* keep compiler quiet */
636+
break;
637+
}
638+
return true;
639+
}
640+
574641
/*
575642
* The opfamily we need to worry about is identified by the index column.
576643
*/
@@ -844,11 +911,18 @@ _bt_checkkeys(IndexScanDesc scan,
844911

845912
if (key->sk_flags&SK_ISNULL)
846913
{
847-
/* Handle IS NULL tests */
848-
Assert(key->sk_flags&SK_SEARCHNULL);
849-
850-
if (isNull)
851-
continue;/* tuple satisfies this qual */
914+
/* Handle IS NULL/NOT NULL tests */
915+
if (key->sk_flags&SK_SEARCHNULL)
916+
{
917+
if (isNull)
918+
continue;/* tuple satisfies this qual */
919+
}
920+
else
921+
{
922+
Assert(key->sk_flags&SK_SEARCHNOTNULL);
923+
if (!isNull)
924+
continue;/* tuple satisfies this qual */
925+
}
852926

853927
/*
854928
* Tuple fails this qual. If it's a required qual for the current

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