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This commit implements the infrastructure to perform asynchronous reads into the buffer pool. To do so, it: - Adds readv AIO callbacks for shared and local buffers It may be worth calling out that shared buffer completions may be run in a different backend than where the IO started. - Adds an AIO wait reference to BufferDesc, to allow backends to wait for in-progress asynchronous IOs - Adapts StartBufferIO(), WaitIO(), TerminateBufferIO(), and their localbuf.c equivalents, to be able to deal with AIO - Moves the code to handle BM_PIN_COUNT_WAITER into a helper function, as it now also needs to be called on IO completion As of this commit, nothing issues AIO on shared/local buffers. A future commit will update StartReadBuffers() to do so. Buffer reads executed through this infrastructure will report invalid page / checksum errors / warnings differently than before: In the error case the error message will cover all the blocks that were included in the read, rather than just the reporting the first invalid block. If more than one block is invalid, the error will include information about the range of the read, the first invalid block and the number of invalid pages, with a HINT towards the server log for per-block details. For the warning case (i.e. zero_damaged_buffers) we would previously emit one warning message for each buffer in a multi-block read. Now there is only a single warning message for the entire read, again referring to the server log for more details in case of multiple checksum failures within a single larger read. Reviewed-by: Noah Misch <noah@leadboat.com> Reviewed-by: Melanie Plageman <melanieplageman@gmail.com> Reviewed-by: Nazir Bilal Yavuz <byavuz81@gmail.com> Discussion: https://postgr.es/m/uvrtrknj4kdytuboidbhwclo4gxhswwcpgadptsjvjqcluzmah%40brqs62irg4dt Discussion: https://postgr.es/m/20210223100344.llw5an2aklengrmn@alap3.anarazel.de Discussion: https://postgr.es/m/stj36ea6yyhoxtqkhpieia2z4krnam7qyetc57rfezgk4zgapf@gcnactj4z56m
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.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.