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First cut at implementing IN (and NOT IN) via hashtables. There is

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more to be done yet, but this is a good start.
This commit is contained in:
Tom Lane
2003-01-12 04:03:34 +00:00
parent 3e54e26bcf
commit 19b886332a
7 changed files with 712 additions and 132 deletions
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26
src/backend/optimizer/plan/subselect.c
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.63 2003/01/10 21:08:11 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.64 2003/01/12 04:03:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -197,9 +197,9 @@ make_subplan(SubLink *slink, List *lefthand)
* NOTE: if you change these numbers, also change cost_qual_eval_walker()
* in path/costsize.c.
*
* XXX If an ALL/ANY subplan is uncorrelated, we may decide to
* materialize its result below. In that case it would've been better
* to specify full retrieval. At present, however, we can only detect
* XXX If an ALL/ANY subplan is uncorrelated, we may decide to hash or
* materialize its result below. In that case it would've been better to
* specify full retrieval. At present, however, we can only detect
* correlation or lack of it after we've made the subplan :-(. Perhaps
* detection of correlation should be done as a separate step.
* Meanwhile, we don't want to be too optimistic about the percentage
@@ -525,10 +525,17 @@ subplan_is_hashable(SubLink *slink, SubPlan *node)
if (subquery_size > SortMem * 1024L)
return false;
/*
* The combining operators must be hashable and strict. (Without
* strictness, behavior in the presence of nulls is too unpredictable.
* We actually must assume even more than plain strictness, see
* nodeSubplan.c for details.)
* The combining operators must be hashable, strict, and self-commutative.
* The need for hashability is obvious, since we want to use hashing.
* Without strictness, behavior in the presence of nulls is too
* unpredictable. (We actually must assume even more than plain
* strictness, see nodeSubplan.c for details.) And commutativity ensures
* that the left and right datatypes are the same; this allows us to
* assume that the combining operators are equality for the righthand
* datatype, so that they can be used to compare righthand tuples as
* well as comparing lefthand to righthand tuples. (This last restriction
* could be relaxed by using two different sets of operators with the
* hash table, but there is no obvious usefulness to that at present.)
*/
foreach(opids, slink->operOids)
{
@@ -542,7 +549,8 @@ subplan_is_hashable(SubLink *slink, SubPlan *node)
if (!HeapTupleIsValid(tup))
elog(ERROR, "cache lookup failed for operator %u", opid);
optup = (Form_pg_operator) GETSTRUCT(tup);
if (!optup->oprcanhash || !func_strict(optup->oprcode))
if (!optup->oprcanhash || optup->oprcom != opid ||
!func_strict(optup->oprcode))
{
ReleaseSysCache(tup);
return false;