revision-id: c56a8839dbf3bfc1fe0df7903eaf67e06c38329c (mariadb-10.4.5-94-gc56a8839dbf) parent(s): bb702c2e4c24632678b548ee1515c6a5b8173808 author: Sergei Petrunia committer: Sergei Petrunia timestamp: 2019-06-28 11:55:53 +0300 message: MDEV-19834: Selectivity of an equality condition discounted twice When discounting selectivity of ref access, don't discount the selectivity we've already discounted for range access. --- mysql-test/main/rowid_filter_innodb.result | 4 ++-- sql/sql_select.cc | 15 +++++++++------ 2 files changed, 11 insertions(+), 8 deletions(-) diff --git a/mysql-test/main/rowid_filter_innodb.result b/mysql-test/main/rowid_filter_innodb.result index d83239eb25f..390c7834a0a 100644 --- a/mysql-test/main/rowid_filter_innodb.result +++ b/mysql-test/main/rowid_filter_innodb.result @@ -2179,7 +2179,7 @@ count(*) 6 explain extended select count(*) from t1 where a in (22,83,11) and b=2; id select_type table type possible_keys key key_len ref rows filtered Extra -1 SIMPLE t1 ref b,a b 5 const 59 55.93 Using where +1 SIMPLE t1 ref b,a b 5 const 59 3.30 Using where Warnings: Note 1003 select count(0) AS `count(*)` from `test`.`t1` where `test`.`t1`.`b` = 2 and `test`.`t1`.`a` in (22,83,11) select * from t1 where a in (22,83,11) and b=2; @@ -2196,7 +2196,7 @@ count(*) 6 explain extended select count(*) from t1 where a in (22,83,11) and b=2; id select_type table type possible_keys key key_len ref rows filtered Extra -1 SIMPLE t1 ref|filter b,a b|a 5|5 const 59 (3%) 55.93 Using where; Using rowid filter +1 SIMPLE t1 ref|filter b,a b|a 5|5 const 59 (3%) 3.30 Using where; Using rowid filter Warnings: Note 1003 select count(0) AS `count(*)` from `test`.`t1` where `test`.`t1`.`b` = 2 and `test`.`t1`.`a` in (22,83,11) select * from t1 where a in (22,83,11) and b=2; diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 23827898160..e11aa991812 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -9028,6 +9028,7 @@ double table_cond_selectivity(JOIN *join, uint idx, JOIN_TAB *s, KEYUSE *keyuse= pos->key; KEYUSE *prev_ref_keyuse= keyuse; uint key= keyuse->key; + bool used_range_selectivity= false; /* Check if we have a prefix of key=const that matches a quick select. @@ -9053,6 +9054,7 @@ double table_cond_selectivity(JOIN *join, uint idx, JOIN_TAB *s, keyparts++; } sel /= (double)table->quick_rows[key] / (double) table->stat_records(); + used_range_selectivity= true; } } @@ -9088,13 +9090,14 @@ double table_cond_selectivity(JOIN *join, uint idx, JOIN_TAB *s, if (keyparts > keyuse->keypart) { /* Ok this is the keyuse that will be used for ref access */ - uint fldno; - if (is_hash_join_key_no(key)) - fldno= keyuse->keypart; - else - fldno= table->key_info[key].key_part[keyparts-1].fieldnr - 1; - if (keyuse->val->const_item()) + if (!used_range_selectivity && keyuse->val->const_item()) { + uint fldno; + if (is_hash_join_key_no(key)) + fldno= keyuse->keypart; + else + fldno= table->key_info[key].key_part[keyparts-1].fieldnr - 1; + if (table->field[fldno]->cond_selectivity > 0) { sel /= table->field[fldno]->cond_selectivity;