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Make 'col IS NULL' clauses be indexable conditions.

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Teodor Sigaev, with some kibitzing from Tom Lane.
This commit is contained in:
Tom Lane
2007-04-06 22:33:43 +00:00
parent 146c83c045
commit f02a82b6ad
19 changed files with 432 additions and 110 deletions
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9
src/include/access/skey.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/skey.h,v 1.34 2007/01/05 22:19:51 momjian Exp $
* $PostgreSQL: pgsql/src/include/access/skey.h,v 1.35 2007/04/06 22:33:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -52,6 +52,12 @@ typedef uint16 StrategyNumber;
* the operator. When using a ScanKey in a heap scan, these fields are not
* used and may be set to InvalidStrategy/InvalidOid.
*
* A ScanKey can also represent a condition "column IS NULL"; this is signaled
* by the SK_SEARCHNULL flag bit. In this case the argument is always NULL,
* and the sk_strategy, sk_subtype, and sk_func fields are not used (unless
* set by the index AM). Currently, SK_SEARCHNULL is supported only for
* index scans, not heap scans; and not all index AMs support it.
*
* Note: in some places, ScanKeys are used as a convenient representation
* for the invocation of an access method support procedure. In this case
* sk_strategy/sk_subtype are not meaningful, and sk_func may refer to a
@ -111,6 +117,7 @@ typedef ScanKeyData *ScanKey;
#define SK_ROW_HEADER 0x0004 /* row comparison header (see above) */
#define SK_ROW_MEMBER 0x0008 /* row comparison member (see above) */
#define SK_ROW_END 0x0010 /* last row comparison member (see above) */
#define SK_SEARCHNULL 0x0020 /* scankey represents a "col IS NULL" qual */
/*