revision-id: 284269212d2c114f3f81b0e18a6eeeaa9247bf08 (mariadb-10.2.31-580-g2842692) parent(s): 984a06db2ce2b2e3c7c5028245905417f2141cd7 author: Igor Babaev committer: Igor Babaev timestamp: 2020-11-12 20:46:08 -0800 message: MDEV-19179 Regression: SELECT ... UNION ... with inconsistent column names fails A bogus error message was issued when a condition was pushed into the having clause of materialized derived table or view specified as union of selects when the corresponding columns of the selects had different names. This happened because the pushed expression was adjusted for the names of the first select of the union. The easiest solution was to rename the columns of the other selects to be name compatible with the columns of the first select. --- mysql-test/r/derived_cond_pushdown.result | 41 +++++++++++++++++++++++++++++++ mysql-test/t/derived_cond_pushdown.test | 28 +++++++++++++++++++++ sql/sql_derived.cc | 25 +++++++++++++++++-- 3 files changed, 92 insertions(+), 2 deletions(-) diff --git a/mysql-test/r/derived_cond_pushdown.result b/mysql-test/r/derived_cond_pushdown.result index d4e8fef..25237aa 100644 --- a/mysql-test/r/derived_cond_pushdown.result +++ b/mysql-test/r/derived_cond_pushdown.result @@ -10593,4 +10593,45 @@ a abc DROP VIEW v1; DROP TABLE t1; +# +# MDEV-19179: pushdown into UNION of aggregation selects whose +# corresponding columns have different names +# +create table t1 (a int); +insert into t1 values (3), (7), (1); +select * +from (select min(a) as x from t1 union all select max(a) as y from t1) t +where x>0; +x +1 +7 +explain extended select * +from (select min(a) as x from t1 union all select max(a) as y from t1) t +where x>0; +id select_type table type possible_keys key key_len ref rows filtered Extra +1 PRIMARY <derived2> ALL NULL NULL NULL NULL 6 100.00 Using where +2 DERIVED t1 ALL NULL NULL NULL NULL 3 100.00 +3 UNION t1 ALL NULL NULL NULL NULL 3 100.00 +Warnings: +Note 1003 select `t`.`x` AS `x` from (select min(`test`.`t1`.`a`) AS `x` from `test`.`t1` having `x` > 0 union all select max(`test`.`t1`.`a`) AS `x` from `test`.`t1` having `x` > 0) `t` where `t`.`x` > 0 +prepare stmt from "select * +from (select min(a) as x from t1 union all select max(a) as y from t1) t +where x>0"; +execute stmt; +x +1 +7 +execute stmt; +x +1 +7 +deallocate prepare stmt; +create view v1(m) as +select min(a) as x from t1 union all select max(a) as y from t1; +select * from v1 where m > 0; +m +1 +7 +drop view v1; +drop table t1; # End of 10.2 tests diff --git a/mysql-test/t/derived_cond_pushdown.test b/mysql-test/t/derived_cond_pushdown.test index a7df65f..31b4904 100644 --- a/mysql-test/t/derived_cond_pushdown.test +++ b/mysql-test/t/derived_cond_pushdown.test @@ -2184,4 +2184,32 @@ SELECT * FROM v1 WHERE IF( a REGEXP 'def', 'foo', a ) IN ('abc', 'foobar'); DROP VIEW v1; DROP TABLE t1; +--echo # +--echo # MDEV-19179: pushdown into UNION of aggregation selects whose +--echo # corresponding columns have different names +--echo # + +create table t1 (a int); +insert into t1 values (3), (7), (1); + +let $q= +select * +from (select min(a) as x from t1 union all select max(a) as y from t1) t +where x>0; + +eval $q; +eval explain extended $q; + +eval prepare stmt from "$q"; +execute stmt; +execute stmt; +deallocate prepare stmt; + +create view v1(m) as +select min(a) as x from t1 union all select max(a) as y from t1; +select * from v1 where m > 0; + +drop view v1; +drop table t1; + --echo # End of 10.2 tests diff --git a/sql/sql_derived.cc b/sql/sql_derived.cc index 39499e6..984044c 100644 --- a/sql/sql_derived.cc +++ b/sql/sql_derived.cc @@ -1199,7 +1199,8 @@ bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived) DBUG_RETURN(false); st_select_lex_unit *unit= derived->get_unit(); - st_select_lex *sl= unit->first_select(); + st_select_lex *first_sl= unit->first_select(); + st_select_lex *sl= first_sl; if (derived->prohibit_cond_pushdown) DBUG_RETURN(false); @@ -1311,7 +1312,27 @@ bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived) if (!extracted_cond_copy) continue; } - + + /* + Rename the columns of all non-first selects of a union to be compatible + by names with the columns of the first select. It will allow to use copies + of the same expression pushed into having clauses of different selects. + */ + if (sl != first_sl) + { + DBUG_ASSERT(sl->item_list.elements == first_sl->item_list.elements); + List_iterator_fast<Item> it(sl->item_list); + List_iterator_fast<Item> nm_it(first_sl->item_list); + Item * item; + char *name; + while((item= it++)) + { + name= (nm_it++)->name; + item->set_name(thd, name, (uint) strlen(name), system_charset_info); + item->is_autogenerated_name= FALSE; + } + } + /* Transform the references to the 'derived' columns from the condition pushed into the having clause of sl to make them usable in the new context