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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
39 lines
1.1 KiB
Plaintext
39 lines
1.1 KiB
Plaintext
SET GLOBAL innodb_undo_log_truncate = 0;
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=== information_schema.innodb_sys_tablespaces and innodb_sys_datafiles ===
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Space_Name Page_Size Zip_Size Path
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innodb_undo001 DEFAULT DEFAULT MYSQLD_DATADIR//undo001
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innodb_undo002 DEFAULT DEFAULT MYSQLD_DATADIR//undo002
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innodb_temporary DEFAULT DEFAULT MYSQLD_DATADIR/ibtmp1
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create table t1(keyc int primary key, c char(100)) engine = innodb;
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create table t2(keyc int primary key, c char(100)) engine = innodb;
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connect con1,localhost,root,,;
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begin;
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insert into t1 select seq,'a' from seq_1_to_20000;
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connect con2,localhost,root,,;
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begin;
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insert into t2 select seq,'a' from seq_1_to_20000;
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connection con1;
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update t1 set c = 'mysql';
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connection con2;
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update t2 set c = 'mysql';
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connection con1;
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update t1 set c = 'oracle';
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connection con2;
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update t2 set c = 'oracle';
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connection con1;
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delete from t1;
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connection con2;
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delete from t2;
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connection con1;
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SET GLOBAL innodb_undo_log_truncate = 1;
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commit;
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disconnect con1;
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connection con2;
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commit;
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disconnect con2;
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connection default;
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SET GLOBAL innodb_max_purge_lag_wait=0;
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set global innodb_fast_shutdown=0;
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# restart
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drop table t1, t2;
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