4ce3afb82e
Use a dedicated struct for the XID/MXID cutoffs used by VACUUM, such as FreezeLimit and OldestXmin. This state is initialized in vacuum.c, and then passed around by code from vacuumlazy.c to heapam.c freezing related routines. The new convention is that everybody works off of the same cutoff state, which is passed around via pointers to const. Also simplify some of the logic for dealing with frozen xmin in heap_prepare_freeze_tuple: add dedicated "xmin_already_frozen" state to clearly distinguish xmin XIDs that we're going to freeze from those that were already frozen from before. That way the routine's xmin handling code is symmetrical with the existing xmax handling code. This is preparation for an upcoming commit that will add page level freezing. Also refactor the control flow within FreezeMultiXactId(), while adding stricter sanity checks. We now test OldestXmin directly, instead of using FreezeLimit as an inexact proxy for OldestXmin. This is further preparation for the page level freezing work, which will make the function's caller cede control of page level freezing to the function where appropriate (where heap_prepare_freeze_tuple sees a tuple that happens to contain a MultiXactId in its xmax). Author: Peter Geoghegan <pg@bowt.ie> Reviewed-By: Jeff Davis <pgsql@j-davis.com> Discussion: https://postgr.es/m/CAH2-WznS9TxXmz2_=SY+SyJyDFbiOftKofM9=aDo68BbXNBUMA@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/.