database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-30 16:24:05 +03:00
Code Activity

MDEV-20515 multi-update tries to position updated table by null reference

Browse Source 
Cause

Join tmp table inserts null row because of OUTER JOIN, that's
expected. Since `multi_update::prepare2()` converted
`Item_temptable_rowid` into `Item_field` (28dbdf3)
`multi_update::send_data()` accesses join tmp record directly and
treats it as a normal row ignoring null status of ref field. NULL ref
field is then treated as normal in `multi_update::do_updates()` which
tries to position updated table by reference 0.

Note that reference 0 may be valid reference and the first row of
table can be wrongly updated (see multi_update.test).

Fix

Do not add row into multi-update tmp table in case of null ref
field. Join tmp table does not have null_row status at this time (as
well as `STATUS_NULL_ROW`) and cannot be skipped by these properties
(see first comment in multi_update::send_data()). But it has all null
fields (including the ref field).
This commit is contained in:
Aleksey Midenkov
2020-04-02 20:48:38 +03:00
parent ba34f409ad
commit 0932c5804d
5 changed files with 63 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
sql/sql_update.cc
View File

@ -2467,6 +2467,9 @@ int multi_update::send_data(List<Item> &not_used_values)
TABLE *tmp_table= tmp_tables[offset];
if (copy_funcs(tmp_table_param[offset].items_to_copy, thd))
DBUG_RETURN(1);
/* rowid field is NULL if join tmp table has null row from outer join */
if (tmp_table->field[0]->is_null())
continue;
/* Store regular updated fields in the row. */
DBUG_ASSERT(1 + unupdated_check_opt_tables.elements ==
tmp_table_param[offset].func_count);
@ -2671,6 +2674,7 @@ int multi_update::do_updates()
uint field_num= 0;
do
{
DBUG_ASSERT(!tmp_table->field[field_num]->is_null());
if (unlikely((local_error=
tbl->file->ha_rnd_pos(tbl->record[0],
(uchar *) tmp_table->