Marko Mäkelä f8c88d905b MDEV-33213 History list is not shrunk unless there is a pause in the workload ... The parameter innodb_undo_log_truncate=ON enables a multi-phased logic: 1. Any "producers" (new starting transactions) are prohibited from using the rollback segments that reside in the undo tablespace. 2. Any transactions that use any of the rollback segments must be committed or aborted. 3. The purge of committed transaction history must process all the rollback segments. 4. The undo tablespace is truncated and rebuilt. 5. The rollback segments are re-enabled for new transactions. There was one flaw in this logic: The first step was not being invoked as often as it could be, and therefore innodb_undo_log_truncate=ON would have no chance to work during a heavy write workload. Independent of innodb_undo_log_truncate, even after commit 86767bcc0f we are missing some chances to free processed undo log pages. If we prohibited the creation of new transactions in one busy rollback segment at a time, we would be eventually guaranteed to be able to free such pages. purge_sys_t::skipped_rseg: The current candidate rollback segment for shrinking the history independent of innodb_undo_log_truncate. purge_sys_t::iterator::free_history_rseg(): Renamed from trx_purge_truncate_rseg_history(). Implement the logic around purge_sys.m_skipped_rseg. purge_sys_t::truncate_undo_space: Renamed from truncate. purge_sys.truncate_undo_space.last: Changed the type to integer to get rid of some pointer dereferencing and conditional branches. purge_sys_t::truncating_tablespace(), purge_sys_t::undo_truncate_try(): Refactored from trx_purge_truncate_history(). Set purge_sys.truncate_undo_space.current if applicable, or return an already set purge_sys.truncate_undo_space.current. purge_coordinator_state::do_purge(): Invoke purge_sys_t::truncating_tablespace() as part of the normal work loop, to implement innodb_undo_log_truncate=ON as often as possible. trx_purge_truncate_rseg_history(): Remove a redundant parameter. trx_undo_truncate_start(): Replace dead code with a debug assertion. Correctness tested by: Matthias Leich Performance tested by: Axel Schwenke Reviewed by: Debarun Banerjee		2024-01-17 11:14:24 +02:00
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srv0mon.cc	Merge branch '10.5' into 10.6	2023-11-08 15:57:05 +01:00
srv0srv.cc	MDEV-33213 History list is not shrunk unless there is a pause in the workload	2024-01-17 11:14:24 +02:00
srv0start.cc	Merge 10.5 into 10.6	2024-01-03 14:24:47 +02:00