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Explain the relationship between vacuumlazy.c's vistest and OldestXmin cutoffs. These closely related cutoffs are different in subtle but important ways. Also document a closely related rule: we must establish rel_pages _after_ OldestXmin to ensure that no XID < OldestXmin can be missed by lazy_scan_heap(). It's easier to explain these issues by initializing everything together, so consolidate initialization of vacrel state. Now almost every vacrel field is initialized by heap_vacuum_rel(). The only remaining exception is the dead_items array, which is still managed by lazy_scan_heap() due to interactions with how we initialize parallel VACUUM. Also move the process that updates pg_class entries for each index into heap_vacuum_rel(), and adjust related assertions. All pg_class updates now take place after lazy_scan_heap() returns, which seems clearer. Author: Peter Geoghegan <pg@bowt.ie> Reviewed-By: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/20211211045710.ljtuu4gfloh754rs@alap3.anarazel.de Discussion: https://postgr.es/m/CAH2-WznYsUxVT156rCQ+q=YD4S4=1M37hWvvHLz-H1pwSM8-Ew@mail.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. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.