firebird/firebird-mirror
firebird/firebird-mirror
8
0
Fork 1
mirror of https://github.com/FirebirdSQL/firebird.git synced 2025-01-22 22:43:03 +01:00
Code Issues

Minor adjustments to the join order selection.

Browse Source
This commit is contained in:
dimitr 2015-03-06 10:24:29 +00:00
parent 3c1c24364a
commit 12da25ce6d
1 changed files with 12 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
src/jrd/Optimizer.cpp
View File

@ -2615,9 +2615,17 @@ bool OptimizerInnerJoin::cheaperRelationship(IndexRelationship* checkRelationshi
const double compareValue = checkRelationship->cost / withRelationship->cost;
if (compareValue >= 0.98 && compareValue <= 1.02)
{
// cost is nearly the same, now check on cardinality
if (checkRelationship->cardinality < withRelationship->cardinality)
// cost is nearly the same, now check uniqueness and cardinality
if (checkRelationship->unique == withRelationship->unique)
{
if (checkRelationship->cardinality < withRelationship->cardinality)
return true;
}
else if (checkRelationship->unique)
return true;
else if (withRelationship->unique)
return false;
}
else if (checkRelationship->cost < withRelationship->cost)
return true;
@ -2932,7 +2940,8 @@ void OptimizerInnerJoin::getIndexedRelationship(InnerJoinStreamInfo* baseStream,
indexRelationship->stream = testStream->stream;
indexRelationship->unique = candidate->unique;
indexRelationship->cost = candidate->cost;
indexRelationship->cardinality = csb_tail->csb_cardinality * candidate->selectivity;
indexRelationship->cardinality = candidate->unique ?
csb_tail->csb_cardinality : csb_tail->csb_cardinality * candidate->selectivity;
// indexRelationship are kept sorted on cost and unique in the indexRelations array.
// The unique and cheapest indexed relatioships are on the first position.