WL#9699: Change innodb_autoinc_lock_mode default to 2
Affects: Server-8.0 — Status: Complete — Priority: Medium
Since the default replication format is now RBR, InnoDB should also change the method of auto increment handling to interleaved. Upgrade Story ------------- In previous versions of MySQL, auto-increment allocation was guaranteed to be sequential in a multi-row insert statement. This had the effect that the auto-increment sequence was effectively locked, and parallel multi-row inserts were not possible. The guarantee of sequential auto_increment sequences is a requirement of statement-based replication, but with the default now row-based replication since MySQL 5.7; it is possible to also change the default auto_increment behavior to 'interleave' values between statements. This change is known to be incompatible with statement based replication, and may break some applications (or user-generated test suites) that depend on a guaranteed sequential auto_increment. The previous default can be restored by setting innodb_autoinc_lock_mode=1.
FR-1) The compiled default value of innodb_autoinc_lock_mode changed from 1 to 2. NFR-1) Any changes required to MTR tests.
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