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Change the division of labor between grouping_planner and query_planner

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so that the latter estimates the number of groups that grouping will
produce.  This is needed because it is primarily query_planner that
makes the decision between fast-start and fast-finish plans, and in the
original coding it was unable to make more than a crude rule-of-thumb
choice when the query involved grouping.  This revision helps us make
saner choices for queries like SELECT ... GROUP BY ... LIMIT, as in a
recent example from Mark Kirkwood.  Also move the responsibility for
canonicalizing sort_pathkeys and group_pathkeys into query_planner;
this information has to be available anyway to support the first change,
and doing it this way lets us get rid of compare_noncanonical_pathkeys
entirely.
This commit is contained in:
Tom Lane
2005-08-27 22:13:44 +00:00
parent 9e56c5a4cf
commit 4e5fbb34b3
7 changed files with 144 additions and 206 deletions
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5
src/backend/nodes/outfuncs.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.259 2005/08/01 20:31:08 tgl Exp $
* $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.260 2005/08/27 22:13:43 tgl Exp $
*
* NOTES
* Every node type that can appear in stored rules' parsetrees *must*
@ -1169,6 +1169,9 @@ _outPlannerInfo(StringInfo str, PlannerInfo *node)
WRITE_NODE_FIELD(full_join_clauses);
WRITE_NODE_FIELD(in_info_list);
WRITE_NODE_FIELD(query_pathkeys);
WRITE_NODE_FIELD(group_pathkeys);
WRITE_NODE_FIELD(sort_pathkeys);
WRITE_FLOAT_FIELD(tuple_fraction, "%.4f");
WRITE_BOOL_FIELD(hasJoinRTEs);
WRITE_BOOL_FIELD(hasOuterJoins);
WRITE_BOOL_FIELD(hasHavingQual);