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Support ORDER BY ... NULLS FIRST/LAST, and add ASC/DESC/NULLS FIRST/NULLS LAST

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per-column options for btree indexes.  The planner's support for this is still
pretty rudimentary; it does not yet know how to plan mergejoins with
nondefault ordering options.  The documentation is pretty rudimentary, too.
I'll work on improving that stuff later.

Note incompatible change from prior behavior: ORDER BY ... USING will now be
rejected if the operator is not a less-than or greater-than member of some
btree opclass.  This prevents less-than-sane behavior if an operator that
doesn't actually define a proper sort ordering is selected.
This commit is contained in:
Tom Lane
2007-01-09 02:14:16 +00:00
parent 3a32ba2f3f
commit 4431758229
65 changed files with 1476 additions and 593 deletions
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21
src/backend/utils/adt/selfuncs.c
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@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.218 2007/01/05 22:19:42 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.219 2007/01/09 02:14:14 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -5101,7 +5101,7 @@ btcostestimate(PG_FUNCTION_ARGS)
if (get_attstatsslot(tuple, InvalidOid, 0,
STATISTIC_KIND_CORRELATION,
index->ordering[0],
index->fwdsortop[0],
NULL, NULL, &numbers, &nnumbers))
{
double varCorrelation;
@ -5116,6 +5116,23 @@ btcostestimate(PG_FUNCTION_ARGS)
free_attstatsslot(InvalidOid, NULL, 0, numbers, nnumbers);
}
else if (get_attstatsslot(tuple, InvalidOid, 0,
STATISTIC_KIND_CORRELATION,
index->revsortop[0],
NULL, NULL, &numbers, &nnumbers))
{
double varCorrelation;
Assert(nnumbers == 1);
varCorrelation = numbers[0];
if (index->ncolumns > 1)
*indexCorrelation = - varCorrelation * 0.75;
else
*indexCorrelation = - varCorrelation;
free_attstatsslot(InvalidOid, NULL, 0, numbers, nnumbers);
}
ReleaseSysCache(tuple);
}