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author | Monty <monty@mariadb.org> | 2017-11-30 17:01:23 +0200 |
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committer | Monty <monty@mariadb.org> | 2017-12-02 12:04:54 +0200 |
commit | c65911ac46c4dc002cf0ea219df54ad086ededd8 (patch) | |
tree | ea94327fa28f6181fecc26407e1a43b97f20d7ae /sql/sql_select.h | |
parent | ddac2d7a1ef725361c7e83b819cb0bec72db024a (diff) | |
download | mariadb-git-c65911ac46c4dc002cf0ea219df54ad086ededd8.tar.gz |
Mark constant 'null_tables' with table->const_table=1
This was done to make thing consistent. It gives the additional benefit
that EXPLAIN EXTENDED now treat null_tables like constant's and replaces
columns with NULL, in a similar way that it replaces columns with constants
for constant tables.
- Null tables are tables where all columns are always NULL. The most common
NULL TABLE is a table used in a LEFT_JOIN that is never true.
- All result changes comes from replacing columns with NULL for null_tables.
- "Impossible where" is now also shows constants for const columns.
- Removed duplicated s->type= JT_CONST
- Reset found_const_table_map when JOIN is created (safety fix)
Diffstat (limited to 'sql/sql_select.h')
-rw-r--r-- | sql/sql_select.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/sql/sql_select.h b/sql/sql_select.h index c1e5a9f95ce..95e9e943c26 100644 --- a/sql/sql_select.h +++ b/sql/sql_select.h @@ -1436,7 +1436,7 @@ public: table_count= 0; top_join_tab_count= 0; const_tables= 0; - const_table_map= 0; + const_table_map= found_const_table_map= 0; aggr_tables= 0; eliminated_tables= 0; join_list= 0; |