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Support "x IS NOT NULL" clauses as indexscan conditions. This turns out

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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 possible
usefulness in its own right, this is an important improvement for
index-optimized MAX/MIN aggregates: it is now reliably possible to get
a column's min or max value cheaply, even when there are a lot of nulls
cluttering the interesting end of the index.
This commit is contained in:
Tom Lane
2010-01-01 21:53:49 +00:00
parent 15faca2596
commit 29c4ad9829
18 changed files with 295 additions and 120 deletions
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13
src/backend/access/gist/gistscan.c
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@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.76 2009/06/11 14:48:53 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.77 2010/01/01 21:53:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -92,15 +92,18 @@ gistrescan(PG_FUNCTION_ARGS)
* field.
*
* Next, if any of keys is a NULL and that key is not marked with
* SK_SEARCHNULL then nothing can be found.
* SK_SEARCHNULL/SK_SEARCHNOTNULL then nothing can be found (ie,
* we assume all indexable operators are strict).
*/
for (i = 0; i < scan->numberOfKeys; i++)
{
scan->keyData[i].sk_func = so->giststate->consistentFn[scan->keyData[i].sk_attno - 1];
ScanKey skey = &(scan->keyData[i]);
if (scan->keyData[i].sk_flags & SK_ISNULL)
skey->sk_func = so->giststate->consistentFn[skey->sk_attno - 1];
if (skey->sk_flags & SK_ISNULL)
{
if ((scan->keyData[i].sk_flags & SK_SEARCHNULL) == 0)
if (!(skey->sk_flags & (SK_SEARCHNULL | SK_SEARCHNOTNULL)))
so->qual_ok = false;
}
}