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MDEV-9500 Bug after upgrade to 10.1.10 (and 10.1.11)

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Case: table with a NOT NULL field, BEFORE UPDATE trigger,
and UPDATE with a subquery that uses GROUP BY on that
NOT NULL field, and needs a temporary table for it.

Because of the BEFORE trigger, the field becomes nullable
temporarily. But its Item_field (used in GROUP BY) doesn't.
When working with the temptable some code looked at
item->maybe_null, some - at field->null_ptr.
The fix: make Item_field nullable when its field is.

This triggers an assert. The group key size is calculated
before the item is made nullable, so the group key doesn't
have a null byte. The fix: make fields/items nullable
before the group key size is calculated.
This commit is contained in:
Sergei Golubchik
2016-02-20 21:06:20 +01:00
parent a38b705fe0
commit 0fcd0ee34e
4 changed files with 26 additions and 2 deletions
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5
sql/sql_update.cc
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@@ -368,6 +368,9 @@ int mysql_update(THD *thd,
if (check_unique_table(thd, table_list))
DBUG_RETURN(TRUE);
switch_to_nullable_trigger_fields(fields, table);
switch_to_nullable_trigger_fields(values, table);
/* Apply the IN=>EXISTS transformation to all subqueries and optimize them. */
if (select_lex->optimize_unflattened_subqueries(false))
DBUG_RETURN(TRUE);
@@ -455,8 +458,6 @@ int mysql_update(THD *thd,
}
init_ftfuncs(thd, select_lex, 1);
switch_to_nullable_trigger_fields(fields, table);
switch_to_nullable_trigger_fields(values, table);
table->mark_columns_needed_for_update();
table->update_const_key_parts(conds);