WL#13950: Deprecate transaction_write_set_extraction
Affects: Server-8.0 — Status: Complete
EXECUTIVE SUMMARY ================= This worklog deprecates the option transaction_write_set_extraction. There shall not be any alternative and the writeset shall always use XXHASH64. The default of transaction_write_set_extraction is XXHASH64 already. Background ========== This worklog implements a deprecation warning when the user sets or reads the value of transaction_write_set_extraction. This WL deprecates the option and warning is logged irrespective of value set. By default server shall always use XXHASH64. The default is XXHASH64 as of WL10477: Defaults: Enable Transaction Write Sets Rationale ========= - We want users to use only XXHASH64 going forward.
FR1. Server SHALL emit a warning in the session when configuring transaction_write_set_extraction Session or Global or persist value in the session (SET GLOBAL transaction_write_set_extraction...) FR2. Server SHALL emit a warning, at server start time, when configuring transaction_write_set_extraction in the server configuration file (transaction_write_set_extraction=..) FR3: Server SHALL emit a warning, at server start time, when passing transaction_write_set_extraction as a server start up option on the command line. FR4: Server SHALL emit a warning in the session when reading transaction_write_set_extraction Session or Global value in the session (SELECT @@GLOBAL.transaction_write_set_extraction...) FR5: RESET PERSIST transaction_write_set_extraction should not generate a warning.
User Visible Changes ==================== - Deprecation Warning in the session when setting transaction_write_set_extraction dynamically The user visible change is that a deprecation warning will be emited when the user configures transaction_write_set_extraction in the session irrespective of the value set: mysql> SET GLOBAL transaction_write_set_extraction=XXHASH64; Query OK, 0 rows affected, 1 warning (0,00 sec) mysql> SHOW WARNINGS\G *************************** 1. row *************************** Level: Warning Code: 1287 Message: '@@transaction_write_set_extraction' is deprecated and will be removed in a future release. 1 row in set (0.01 sec) - Deprecation Warning in the error log when setting transaction-write-set-extraction in the server configuration The user visible change is that a deprecation warning will be emited when the user configures transaction-write-set-extraction in the config file and the server is restarted. Example: 2020-08-14T11:05:22.830731Z 0 [Warning] [MY-011069] [Server] The syntax '--transaction-write-set-extraction' is deprecated and will be removed in a future release. Upgrades ======== After using MySQL 8, the user will get the deprecation warnings as described in the previous section. This however, shall not break backwards compatibility. Security ======== There are no security considerations. Observability ============= There are no observability considerations. There is no new functionality added only a new warning is emited.
LOW LEVEL CHANGES ================= 1. Deploy DEPRECATED_VAR("") in the transaction-write-set-extraction variable declaration. 2. Deploy conditional calls to push_deprecated_warn in mysql_get_one_options, for transaction-write-set-extraction, so that the warning is pushed at server start time, when the options is set. 3. Add test case validating session, global, persist and server start warnings.
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