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MDEV-32050: Deprecate&ignore innodb_purge_rseg_truncate_frequency

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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
This commit is contained in:
Marko Mäkelä
2023-10-25 09:11:58 +03:00
parent 21bec97044
commit 14685b10df
107 changed files with 102 additions and 331 deletions
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3
mysql-test/suite/innodb_zip/r/blob.result
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@@ -2,8 +2,6 @@
# MDEV-21259 Assertion 'w != NORMAL || mach_read_from_4(ptr) != val'
# failed in mtr_t::write(), btr_free_externally_stored_field()
#
SET @saved_frequency = @@GLOBAL.innodb_purge_rseg_truncate_frequency;
SET GLOBAL innodb_purge_rseg_truncate_frequency = 1;
CREATE TABLE t1 (c TEXT, f2 INT PRIMARY KEY, f3 INT UNIQUE)
ENGINE=InnoDB ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=4;
SET @level= @@GLOBAL.innodb_compression_level;
@@ -18,4 +16,3 @@ disconnect prevent_purge;
InnoDB 0 transactions not purged
DROP TABLE t1;
SET GLOBAL innodb_compression_level = @level;
SET GLOBAL innodb_purge_rseg_truncate_frequency = @saved_frequency;