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We've made multiple attempts at preventing get_actual_variable_range from taking an unreasonable amount of time (3ca930fc3, fccebe421). But there's still an issue for the very first planning attempt after deletion of a large number of extremal-valued tuples. While that planning attempt will set "killed" bits on the tuples it visits and thereby reduce effort for next time, there's still a lot of work it has to do to visit the heap and then set those bits. It's (usually?) not worth it to do that much work at plan time to have a slightly better estimate, especially in a context like this where the table contents are known to be mutating rapidly. Therefore, let's bound the amount of work to be done by giving up after we've visited 100 heap pages. Giving up just means we'll fall back on the extremal value recorded in pg_statistic, so it shouldn't mean that planner estimates suddenly become worthless. Note that this means we'll still gradually whittle down the problem by setting a few more index "killed" bits in each planning attempt; so eventually we'll reach a good state (barring further deletions), even in the absence of VACUUM. Simon Riggs, per a complaint from Jakub Wartak (with cosmetic adjustments by me). Back-patch to all supported branches. Discussion: https://postgr.es/m/CAKZiRmznOwi0oaV=4PHOCM4ygcH4MgSvt8=5cu_vNCfc8FSUug@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/.