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MDEV-24346 valgrind error in main.precedence

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in queries like

  create view v1 as select 2 like 1 escape (3 in (select 0 union select 1));
  select 2 union select * from v1;

Item_func_like::escape was left uninitialized, because
Item_in_optimizer is const_during_execution()
but not actually const_item() during execution.

It's not, because const subquery evaluation was disabled for derived.
Practically it only needs to be disabled for multi-update
that runs fix_fields() before all tables are locked.
This commit is contained in:
Sergei Golubchik 2020-12-14 18:25:08 +01:00
parent 5785de72ac
commit a587ded283
5 changed files with 14 additions and 3 deletions
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1
mysql-test/suite/innodb/r/innodb_multi_update.result
View file

@ -81,4 +81,5 @@ CREATE TABLE t1(f1 INT) ENGINE=INNODB;
INSERT INTO t1 VALUES(1);
UPDATE (SELECT ((SELECT 1 FROM t1), 1) FROM t1 WHERE (SELECT 1 FROM t1)) x, (SELECT 1) AS d SET d.f1 = 1;
ERROR 21000: Operand should contain 1 column(s)
UPDATE (SELECT ((SELECT 1 FROM t1),1) = (1,1) FROM t1 WHERE (SELECT 1 FROM t1)) x, t1 AS d SET d.f1 = 1;
DROP TABLE t1;

1
mysql-test/suite/innodb/t/innodb_multi_update.test
View file

@ -35,4 +35,5 @@ CREATE TABLE t1(f1 INT) ENGINE=INNODB;
INSERT INTO t1 VALUES(1);
--error ER_OPERAND_COLUMNS
UPDATE (SELECT ((SELECT 1 FROM t1), 1) FROM t1 WHERE (SELECT 1 FROM t1)) x, (SELECT 1) AS d SET d.f1 = 1;
UPDATE (SELECT ((SELECT 1 FROM t1),1) = (1,1) FROM t1 WHERE (SELECT 1 FROM t1)) x, t1 AS d SET d.f1 = 1;
DROP TABLE t1;

6
sql/item_cmpfunc.cc
View file

@ -5261,6 +5261,7 @@ void Item_func_like::print(String *str, enum_query_type query_type)
longlong Item_func_like::val_int()
{
DBUG_ASSERT(fixed == 1);
DBUG_ASSERT(escape != -1);
String* res= args[0]->val_str(&cmp_value1);
if (args[0]->null_value)
{
@ -5352,10 +5353,13 @@ bool fix_escape_item(THD *thd, Item *escape_item, String *tmp_str,
my_error(ER_WRONG_ARGUMENTS,MYF(0),"ESCAPE");
return TRUE;
}
IF_DBUG(*escape= -1,);
if (escape_item->const_item())
{
/* If we are on execution stage */
/* XXX is it safe to evaluate is_expensive() items here? */
String *escape_str= escape_item->val_str(tmp_str);
if (escape_str)
{

2
sql/sql_derived.cc
View file

@ -738,14 +738,12 @@ bool mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *derived)
!(derived->derived_result= new (thd->mem_root) select_union(thd)))
DBUG_RETURN(TRUE); // out of memory
lex->context_analysis_only|= CONTEXT_ANALYSIS_ONLY_DERIVED;
// st_select_lex_unit::prepare correctly work for single select
if ((res= unit->prepare(thd, derived->derived_result, 0)))
goto exit;
if (derived->with &&
(res= derived->with->rename_columns_of_derived_unit(thd, unit)))
goto exit;
lex->context_analysis_only&= ~CONTEXT_ANALYSIS_ONLY_DERIVED;
if ((res= check_duplicate_names(thd, unit->types, 0)))
goto exit;

7
sql/sql_update.cc
View file

@ -1534,7 +1534,11 @@ int mysql_multi_update_prepare(THD *thd)
During prepare phase acquire only S metadata locks instead of SW locks to
keep prepare of multi-UPDATE compatible with concurrent LOCK TABLES WRITE
and global read lock.
Don't evaluate any subqueries even if constant, because
tables aren't locked yet.
*/
lex->context_analysis_only|= CONTEXT_ANALYSIS_ONLY_DERIVED;
if (thd->lex->sql_command == SQLCOM_UPDATE_MULTI)
{
if (open_tables(thd, &table_list, &table_count,
@ -1557,6 +1561,9 @@ int mysql_multi_update_prepare(THD *thd)
{
DBUG_RETURN(TRUE);
}
lex->context_analysis_only&= ~CONTEXT_ANALYSIS_ONLY_DERIVED;
(void) read_statistics_for_tables_if_needed(thd, table_list);
/* @todo: downgrade the metadata locks here. */