mirror of
https://github.com/MariaDB/server.git
synced 2025-12-07 17:42:39 +03:00
14685b10df
The motivation of introducing the parameter innodb_purge_rseg_truncate_frequency in mysql/mysql-server@28bbd66ea5 and mysql/mysql-server@8fc2120fed seems to have been to avoid stalls due to freeing undo log pages or truncating undo log tablespaces. In MariaDB Server, innodb_undo_log_truncate=ON should be a much lighter operation than in MySQL, because it will not involve any log checkpoint. Another source of performance stalls should be trx_purge_truncate_rseg_history(), which is shrinking the history list by freeing the undo log pages whose undo records have been purged. To alleviate that, we will introduce a purge_truncation_task that will offload this from the purge_coordinator_task. In that way, the next innodb_purge_batch_size pages may be parsed and purged while the pages from the previous batch are being freed and the history list being shrunk. The processing of innodb_undo_log_truncate=ON will still remain the responsibility of the purge_coordinator_task. purge_coordinator_state::count: Remove. We will ignore innodb_purge_rseg_truncate_frequency, and act as if it had been set to 1 (the maximum shrinking frequency). purge_coordinator_state::do_purge(): Invoke an asynchronous task purge_truncation_callback() to free the undo log pages. purge_sys_t::iterator::free_history(): Free those undo log pages that have been processed. This used to be a part of trx_purge_truncate_history(). purge_sys_t::clone_end_view(): Take a new value of purge_sys.head as a parameter, so that it will be updated while holding exclusive purge_sys.latch. This is needed for race-free access to the field in purge_truncation_callback(). Reviewed by: Vladislav Lesin
106 lines
3.6 KiB
Plaintext
106 lines
3.6 KiB
Plaintext
SET @saved_include_delete_marked = @@GLOBAL.innodb_stats_include_delete_marked;
|
|
SET GLOBAL innodb_stats_include_delete_marked = ON;
|
|
SET @saved_traditional = @@GLOBAL.innodb_stats_traditional;
|
|
SET GLOBAL innodb_stats_traditional=false;
|
|
SET @saved_modified_counter = @@GLOBAL.innodb_stats_modified_counter;
|
|
SET GLOBAL innodb_stats_modified_counter=1;
|
|
CREATE TABLE t1 (id SERIAL, val INT UNSIGNED NOT NULL, KEY(val))
|
|
ENGINE=INNODB STATS_PERSISTENT=1,STATS_AUTO_RECALC=1;
|
|
CREATE TABLE t2 LIKE t1;
|
|
INSERT INTO t1 (val) SELECT 4 FROM seq_1_to_16;
|
|
ANALYZE TABLE t1;
|
|
Table Op Msg_type Msg_text
|
|
test.t1 analyze status Engine-independent statistics collected
|
|
test.t1 analyze status OK
|
|
connect con1, localhost, root,,;
|
|
START TRANSACTION;
|
|
DELETE FROM t1;
|
|
SELECT COUNT(*) FROM t1;
|
|
connection default;
|
|
# With innodb_stats_include_delete_marked=ON,
|
|
# DELETE must not affect statistics before COMMIT.
|
|
EXPLAIN SELECT * FROM t1 WHERE val=4;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t1 ref val val 4 const 1 Using index
|
|
connection con1;
|
|
COUNT(*)
|
|
0
|
|
ROLLBACK;
|
|
SELECT COUNT(*) FROM t1;
|
|
COUNT(*)
|
|
16
|
|
EXPLAIN SELECT * FROM t1 WHERE val=4;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t1 ref val val 4 const 16 Using index
|
|
BEGIN;
|
|
DELETE FROM t1;
|
|
COMMIT;
|
|
SELECT COUNT(*) FROM t1;
|
|
COUNT(*)
|
|
0
|
|
connection default;
|
|
BEGIN;
|
|
INSERT INTO t2 (val) SELECT 4 FROM seq_1_to_16;
|
|
# The INSERT will show up before COMMIT.
|
|
EXPLAIN SELECT * FROM t2 WHERE val=4;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t2 ref val val 4 const 16 Using index
|
|
SELECT COUNT(*) FROM t2;
|
|
COUNT(*)
|
|
16
|
|
# The ROLLBACK of the INSERT must affect the statistics.
|
|
ROLLBACK;
|
|
SELECT COUNT(*) FROM t2;
|
|
COUNT(*)
|
|
0
|
|
connection con1;
|
|
EXPLAIN SELECT * FROM t2 WHERE val=4;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t2 ref val val 4 const 1 Using index
|
|
InnoDB 0 transactions not purged
|
|
# After COMMIT and purge, the DELETE must show up.
|
|
EXPLAIN SELECT * FROM t1 WHERE val=4;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t1 ref val val 4 const 1 Using index
|
|
SET GLOBAL innodb_stats_include_delete_marked = OFF;
|
|
BEGIN;
|
|
INSERT INTO t1 (val) SELECT 4 FROM seq_1_to_16;
|
|
EXPLAIN SELECT * FROM t1 WHERE val=4;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t1 ref val val 4 const 16 Using index
|
|
ROLLBACK;
|
|
EXPLAIN SELECT * FROM t1 WHERE val=4;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t1 ref val val 4 const 1 Using index
|
|
BEGIN;
|
|
INSERT INTO t1 (val) SELECT 4 FROM seq_1_to_16;
|
|
COMMIT;
|
|
EXPLAIN SELECT * FROM t1 WHERE val=4;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t1 ref val val 4 const 16 Using index
|
|
BEGIN;
|
|
DELETE FROM t1;
|
|
SELECT COUNT(*) FROM t1;
|
|
COUNT(*)
|
|
0
|
|
# With innodb_stats_include_delete_marked=OFF,
|
|
# DELETE must affect statistics even before COMMIT.
|
|
# However, if there was a WHERE condition,
|
|
# ha_innobase::records_in_range() would count the delete-marked records.
|
|
EXPLAIN SELECT * FROM t1;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t1 index NULL val 4 NULL 16 Using index
|
|
ROLLBACK;
|
|
EXPLAIN SELECT * FROM t1;
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|
1 SIMPLE t1 index NULL val 4 NULL 16 Using index
|
|
SELECT COUNT(*) FROM t1;
|
|
COUNT(*)
|
|
16
|
|
disconnect con1;
|
|
connection default;
|
|
DROP TABLE t1,t2;
|
|
SET GLOBAL innodb_stats_include_delete_marked = @saved_include_delete_marked;
|
|
SET GLOBAL innodb_stats_traditional = @saved_traditional;
|
|
SET GLOBAL innodb_stats_modified_counter = @saved_modified_counter;
|