mirror of
https://github.com/postgres/postgres.git
synced 2025-08-31 17:02:12 +03:00
fc02e6724f
In e6799d5a53 I removed vacuumlazy.c trickery around re-checking
whether a page is actually empty after acquiring an extension lock on
the relation, because the page is not PageInit()ed anymore, and
entries in the FSM ought not to lead to user-visible errors.
As reported by various buildfarm animals that is not correct, given
the way to code currently stands: If vacuum processes a page that's
just been newly added by either RelationGetBufferForTuple() or
RelationAddExtraBlocks(), it could add that page to the FSM and it
could be reused by other backends, before those two functions check
whether the newly added page is actually new. That's a relatively
narrow race, but several buildfarm machines appear to be able to hit
it.
While it seems wrong that the FSM, given it's lack of durability and
approximative nature, can trigger errors like this, that seems better
fixed in a separate commit. Especially given that a good portion of
the buildfarm is red, and this is just re-introducing logic that
existed a few hours ago.
Author: Andres Freund
Discussion: https://postgr.es/m/20190128222259.zhi7ovzgtkft6em6@alap3.anarazel.de
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. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.