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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
12 lines
433 B
Text
12 lines
433 B
Text
SET GLOBAL
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innodb_file_per_table=OFF,
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innodb_immediate_scrub_data_uncompressed=ON;
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CREATE TABLE t1(f1 INT NOT NULL, f2 INT NOT NULL,
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f3 INT NOT NULL, INDEX(f1),
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INDEX(f2), INDEX(f3))ENGINE=InnoDB;
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INSERT INTO t1 SELECT seq, seq, seq FROM seq_1_to_16384;
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INSERT INTO t1 SELECT seq, seq, seq FROM seq_1_to_16384;
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INSERT INTO t1 SELECT seq, seq, seq FROM seq_1_to_16384;
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DROP TABLE t1;
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SET GLOBAL innodb_max_purge_lag_wait=0;
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# restart
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