bf3dba508e
This commit reverts818fefd8fd, that has been introduced to address a an instability in some of the TAP tests due to the presence of random standby snapshot WAL records, when slots are invalidated by InvalidatePossiblyObsoleteSlot(). Anyway, this commit had also the consequence of introducing a behavior regression. After818fefd8fd, the code may determine that a slot needs to be invalidated while it may not require one: the slot may have moved from a conflicting state to a non-conflicting state between the moment when the mutex is released and the moment when we recheck the slot, in InvalidatePossiblyObsoleteSlot(). Hence, the invalidations may be more aggressive than they actually have to.105b2cb336has tackled the test instability in a way that should be hopefully sufficient for the buildfarm, even for slow members: - In v18, the test relies on an injection point that bypasses the creation of the random records generated for standby snapshots, eliminating the random factor that impacted the test. This option was not available when818fefd8fdwas discussed. - In v16 and v17, the problem was bypassed by disallowing a slot to become active in some of the scenarios tested. While on it, this commit adds a comment to document that it is fine for a recheck to use xmin and LSN values stored in the slot, without storing and reusing them across multiple checks. Reported-by: "suyu.cmj" <mengjuan.cmj@alibaba-inc.com> Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com> Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Discussion: https://postgr.es/m/f492465f-657e-49af-8317-987460cb68b0.mengjuan.cmj@alibaba-inc.com Backpatch-through: 16
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
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