648a7e28d7
lazy_scan_prune() takes a parameter from lazy_scan_heap() indicating whether the page was marked all-visible in the VM at the time it was last checked in find_next_unskippable_block(). This behavior is historical, dating back to commit 608195a3a365, when we did not pin the VM page until deciding we must read it. Now that the VM page is already pinned, there is no meaningful benefit to relying on a cached VM status. Removing this cached value simplifies the logic in both lazy_scan_heap() and lazy_scan_prune(). It also clarifies future work that will set the visibility map on-access: such paths will not have a cached value available, which would make the logic harder to reason about. And eliminating it enables us to detect and repair VM corruption on-access. Along with removing the cached value and unconditionally checking the visibility status of the heap page, this commit also moves the VM corruption handling to occur first. This reordering should have no performance impact, since the checks are inexpensive and performed only once per page. It does, however, make the control flow easier to understand. The new restructuring also makes it possible to set the VM after fixing corruption (if pruning found the page all-visible). Now that no callers of visibilitymap_set() use its return value, change its (and visibilitymap_set_vmbits()) return type to void. Author: Melanie Plageman <melanieplageman@gmail.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Kirill Reshke <reshkekirill@gmail.com> Reviewed-by: Chao Li <li.evan.chao@gmail.com> Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru> Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com> Discussion: https://postgr.es/m/5CEAA162-67B1-44DA-B60D-8B65717E8B05%40gmail.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/.