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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
19 lines
664 B
Plaintext
19 lines
664 B
Plaintext
#
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# MDEV-21259 Assertion 'w != NORMAL || mach_read_from_4(ptr) != val'
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# failed in mtr_t::write(), btr_free_externally_stored_field()
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#
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CREATE TABLE t1 (c TEXT, f2 INT PRIMARY KEY, f3 INT UNIQUE)
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ENGINE=InnoDB ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=4;
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SET @level= @@GLOBAL.innodb_compression_level;
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SET GLOBAL innodb_compression_level=0;
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connect prevent_purge,localhost,root;
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START TRANSACTION WITH CONSISTENT SNAPSHOT;
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connection default;
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INSERT INTO t1 VALUES('a',1,0);
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UPDATE t1 SET c= REPEAT('a b ',4096);
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REPLACE INTO t1 SELECT * FROM t1;
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disconnect prevent_purge;
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InnoDB 0 transactions not purged
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DROP TABLE t1;
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SET GLOBAL innodb_compression_level = @level;
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