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| author | Sergei Petrunia <psergey@askmonty.org> | 2019-09-10 23:51:42 +0300 |
|---|---|---|
| committer | Sergei Petrunia <psergey@askmonty.org> | 2019-09-11 17:06:50 +0300 |
| commit | c8dc866fdeee551993ef91fb321135f9106ea00e (patch) | |
| tree | d74301fbc473f28660e57b43bc836fc3b643f628 /sql/sql_select.h | |
| parent | 863a95173110e1528e7a47fe688fea8784eb67b6 (diff) | |
| download | mariadb-git-c8dc866fdeee551993ef91fb321135f9106ea00e.tar.gz | |
MDEV-20371: Invalid reads at plan refinement stage: join->positions...
best_access_path() is called from two optimization phases:
1. Plan choice phase, in choose_plan(). Here, the join prefix being
considered is in join->positions[]
2. Plan refinement stage, in fix_semijoin_strategies_for_picked_join_order
Here, the join prefix is in join->best_positions[]
It used to access join->positions[] from stage #2. This didnt cause any
valgrind or asan failures (as join->positions[] has been written-to before)
but the effect was similar to that of reading the random data:
The join prefix we've picked (in join->best_positions) could have
nothing in common with the join prefix that was last to be considered
(in join->positions).
Diffstat (limited to 'sql/sql_select.h')
| -rw-r--r-- | sql/sql_select.h | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/sql/sql_select.h b/sql/sql_select.h index 60c2ce55a16..fe44f448446 100644 --- a/sql/sql_select.h +++ b/sql/sql_select.h @@ -792,6 +792,7 @@ public: friend void best_access_path(JOIN *join, JOIN_TAB *s, table_map remaining_tables, + const struct st_position *join_positions, uint idx, bool disable_jbuf, double record_count, @@ -1960,6 +1961,11 @@ protected: } }; +void best_access_path(JOIN *join, JOIN_TAB *s, + table_map remaining_tables, + const POSITION *join_positions, uint idx, + bool disable_jbuf, double record_count, + POSITION *pos, POSITION *loose_scan_pos); bool cp_buffer_from_ref(THD *thd, TABLE *table, TABLE_REF *ref); bool error_if_full_join(JOIN *join); int report_error(TABLE *table, int error); @@ -2277,7 +2283,7 @@ bool instantiate_tmp_table(TABLE *table, KEY *keyinfo, ulonglong options); bool open_tmp_table(TABLE *table); void setup_tmp_table_column_bitmaps(TABLE *table, uchar *bitmaps); -double prev_record_reads(POSITION *positions, uint idx, table_map found_ref); +double prev_record_reads(const POSITION *positions, uint idx, table_map found_ref); void fix_list_after_tbl_changes(SELECT_LEX *new_parent, List<TABLE_LIST> *tlist); struct st_cond_statistic |