74eafeab1a
Until now StartBufferIO() had a few weaknesses: - As it did not submit staged IOs, it was not safe to call StartBufferIO() where there was a potential for unsubmitted IO, which required AsyncReadBuffers() to use a wrapper (ReadBuffersCanStartIO()) around StartBufferIO(). - With nowait = true, the boolean return value did not allow to distinguish between no IO being necessary and having to wait, which would lead ReadBuffersCanStartIO() to unnecessarily submit staged IO. - Several callers needed to handle both local and shared buffers, requiring the caller to differentiate between StartBufferIO() and StartLocalBufferIO() - In a future commit some callers of StartBufferIO() want the BufferDesc's io_wref to be returned, to asynchronously wait for in-progress IO - Indicating whether to wait with the nowait parameter was somewhat confusing compared to a wait parameter Address these issues as follows: - StartBufferIO() is renamed to StartSharedBufferIO() - A new StartBufferIO() is introduced that supports both shared and local buffers - The boolean return value has been replaced with an enum, indicating whether the IO is already done, already in progress or that the buffer has been readied for IO - A new PgAioWaitRef * argument allows the caller to get the wait reference is desired. All current callers pass NULL, a user of this will be introduced subsequently - Instead of the nowait argument there now is wait This probably would not have been worthwhile on its own, but since all these lines needed to be touched anyway... Author: Andres Freund <andres@anarazel.de> Author: Melanie Plageman <melanieplageman@gmail.com> Discussion: https://postgr.es/m/zljergweqti7x67lg5ije2rzjusie37nslsnkjkkby4laqqbfw@3p3zu522yykv |
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| configure | ||
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| README.md | ||
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/.