92fc6856cb
To avoid pinning too much of the buffer pool at once, read_stream.c previously used LimitAdditionalPins(). The coding was naive, and only considered the available buffers at stream construction time. This commit checks before each StartReadBuffers() call with GetAdditionalPinLimit(). The result might change over time due to pins acquired outside this stream by the same backend. No extra CPU cycles are added to the all-buffered fast-path code, but the I/O-starting path now considers the up-to-date remaining buffer limit. In practice it was quite difficult to exceed limits and cause any real problems in v17, so no back-patch for now, but proposed changes will make it easier. Per code review from Andres, in the course of testing his AIO patches. Reviewed-by: Andres Freund <andres@anarazel.de> (earlier versions) Discussion: https://postgr.es/m/CA%2BhUKGK_%3D4CVmMHvsHjOVrK6t4F%3DLBpFzsrr3R%2BaJYN8kcTfWg%40mail.gmail.com
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/.