database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-11-09 11:41:36 +03:00
Code Activity

MDEV-37345 sequences and prelocking

Browse Source 
if a bunch of tables are prelocked, when a table is actually
needed in the routine, open_tables picks one table out of the
prelocked list with a smallest "distance". Distance is simply
a difference between the actual table lock and the requested
table lock. Say, if the prelocked set contains both t1 write-locked
and t1 read-locked, than an UPDATE will prefer write-locked t1
and SELECT will prefer read-locked. if there's only write-locked
table in the set, both UPDATE and SELECT will use it.

this doesn't distingush between UPDATE and INSERT, but INSERT
marks tables with tables->for_insert_data=1, which causes
prelocking to invoke add_internal_tables() and prepare sequences
for execution.

in this bug there were two prelocked t1's, one for INSERT (with
for_insert_data=1) and one for UPDATE.
INSERT picks the second (they both are write-locked, so the distance is
the same), its sequence is not prepared and crashes.

Let's add for_insert_data as the lowest bit into the distance.
This commit is contained in:
Sergei Golubchik
2025-10-23 14:21:14 +02:00
parent 2bf1d089cf
commit 516f68af9e
3 changed files with 48 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
mysql-test/suite/sql_sequence/other.result
View File

@@ -394,4 +394,20 @@ create table t (id bigint default(nextval(s))) engine=myisam;
insert delayed into t () values();
drop table t;
drop sequence s;
#
# MDEV-37345 Item_func_nextval::val_int() crash on INSERT...SELECT with subqueries
#
create sequence s;
create table t1 (a int, b int default(nextval(s)));
insert into t1 () values ();
create table t2 (c int);
create procedure p() update t1 set a = 0;
create trigger tr after insert on t2 for each row
begin
insert into t1 () values ();
call p();
end $
insert into t2 values ();
drop table t1, t2, s;
drop procedure p;
# End of 10.11 tests

20
mysql-test/suite/sql_sequence/other.test
View File

@@ -428,4 +428,24 @@ insert delayed into t () values();
drop table t;
drop sequence s;
--echo #
--echo # MDEV-37345 Item_func_nextval::val_int() crash on INSERT...SELECT with subqueries
--echo #
# sequence and prelocking.
create sequence s;
create table t1 (a int, b int default(nextval(s)));
insert into t1 () values ();
create table t2 (c int);
create procedure p() update t1 set a = 0;
--delimiter $
create trigger tr after insert on t2 for each row
begin
insert into t1 () values ();
call p();
end $
--delimiter ;
insert into t2 values ();
drop table t1, t2, s;
drop procedure p;
--echo # End of 10.11 tests