diff options
| author | Varun Gupta <varunraiko1803@gmail.com> | 2018-06-09 11:26:52 +0530 |
|---|---|---|
| committer | Varun Gupta <varunraiko1803@gmail.com> | 2018-06-09 11:40:28 +0530 |
| commit | cd33280b682692f0517a26178d7b5337db648751 (patch) | |
| tree | c1f44cf1e5ba5f52809a84e39c353a4fe2035428 /sql/table.cc | |
| parent | 15155ecd3483c47d8f2c05727184f6bf47bbf0b0 (diff) | |
| download | mariadb-git-cd33280b682692f0517a26178d7b5337db648751.tar.gz | |
MDEV-16374: Filtered shows 0 for materilization scan for a semi join, which makes optimizer always picks
materialization scan over materialization lookup
For non-mergeable semi-joins we don't store the estimates of the IN subquery in table->file->stats.records.
In the function TABLE_LIST::fetch_number_of_rows, we store the number of rows in the tables
(estimates in case of derived table/views).
Currently we don't store the estimates for non-mergeable semi-joins, which leads to a problem of selecting
materialization scan over materialization lookup.
Fixed this by storing these estimated appropriately
Diffstat (limited to 'sql/table.cc')
| -rw-r--r-- | sql/table.cc | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/sql/table.cc b/sql/table.cc index bc6e1e754ee..b5082df7076 100644 --- a/sql/table.cc +++ b/sql/table.cc @@ -7099,7 +7099,15 @@ int TABLE_LIST::fetch_number_of_rows() { int error= 0; if (jtbm_subselect) + { + if (jtbm_subselect->is_jtbm_merged) + { + table->file->stats.records= jtbm_subselect->jtbm_record_count; + set_if_bigger(table->file->stats.records, 2); + table->used_stat_records= table->file->stats.records; + } return 0; + } if (is_materialized_derived() && !fill_me) { |