755a4c10d1
With real AIO it doesn't make sense to cross segment boundaries with one IO. Add smgrmaxcombine() to allow upper layers to query which buffers can be merged. We could continue to cross segment boundaries when not using AIO, but it doesn't really make sense, because md.c will never be able to perform the read across the segment boundary in one system call. Which means we'll mark more buffers as undergoing IO than really makes sense - if another backend desires to read the same blocks, it'll be blocked longer than necessary. So it seems better to just never cross the boundary. Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Reviewed-by: Noah Misch <noah@leadboat.com> Discussion: https://postgr.es/m/1f6b50a7-38ef-4d87-8246-786d39f46ab9@iki.fi
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/.