9ba3ec076a
During pruning, we keep track of the newest xmin of live tuples on the page visible to all running and future transactions so that we can use it later as the snapshot conflict horizon when setting the VM if the page turns out to be all-visible. Previously, we stopped updating this value once we determined the page was not all-visible. However, maintaining it even when the page is not all-visible is inexpensive and makes the snapshot conflict horizon calculation clearer. This guarantees it won't contain a stale value. Since we'll keep it up to date all the time now anyway, there's no reason not to maintain set_all_visible for on-access pruning. This will allow us to set the VM on-access in the future. Author: Melanie Plageman <melanieplageman@gmail.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Chao Li <li.evan.chao@gmail.com> Discussion: https://postgr.es/m/bqc4kh5midfn44gnjiqez3bjqv4zogydguvdn446riw45jcf3y%404ez66il7ebvk |
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| configure | ||
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| COPYRIGHT | ||
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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/.