ed0b87caac
In preparation for a follow-up change to the buffer manager, teach read_stream.c to manage buffers "forwarded" from one StartReadBuffers() call to the next after a short read. This involves a small amount of extra book-keeping, and opens the way for lower levels to split I/O operations without having to drop pins, as required for efficient handling of various edge cases. Concretely, the "buffers" argument will change from an out parameter to an in/out parameter. Buffer queue elements must be initialized on first use and cleared after they're consumed, but forwarded buffers are left where they fall ahead of the current pending read in the queue, ready for use by the operation that continues where a short read left off. The stream also needs to count them for pin limit management and release them on reset/early end. Tested-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/.