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MDEV-8989: ORDER BY optimizer ignores equality propagation

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Variant #4 of the fix.

Make ORDER BY optimization functions take into account multiple
equalities. This is done in several places:
- remove_const() checks whether we can sort the first table in the
  join, or we need to put rows into temp.table and then sort.
- test_if_order_by_key() checks whether there are indexes that
  can be used to produce the required ordering
- make_unireg_sortorder() constructs sort criteria for filesort.
This commit is contained in:
Sergei Petrunia
2016-05-23 21:15:01 +03:00
parent 9c9747fed3
commit 99cd5a962c
13 changed files with 414 additions and 21 deletions
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2
sql/sql_delete.cc
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@ -499,7 +499,7 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
Filesort_tracker *fs_tracker=
thd->lex->explain->get_upd_del_plan()->filesort_tracker;
if (!(sortorder= make_unireg_sortorder(thd, order, &length, NULL)) ||
if (!(sortorder= make_unireg_sortorder(thd, NULL, 0, order, &length, NULL)) ||
(table->sort.found_records= filesort(thd, table, sortorder, length,
select, HA_POS_ERROR,
true,