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Previously we initialized pages when bulk extending in RelationAddExtraBlocks(). That has a major disadvantage: It ties RelationAddExtraBlocks() to heap, as other types of storage are likely to need different amounts of special space, have different amount of free space (previously determined by PageGetHeapFreeSpace()). That we're relying on initializing pages, but not WAL logging the initialization, also means the risk for getting "WARNING: relation \"%s\" page %u is uninitialized --- fixing" style warnings in vacuums after crashes/immediate shutdowns, is considerably higher. The warning sounds much more serious than what they are. Fix those two issues together by not initializing pages in RelationAddExtraPages() (but continue to do so in RelationGetBufferForTuple(), which is linked much more closely to heap), and accepting uninitialized pages as normal in vacuumlazy.c. When vacuumlazy encounters an empty page it now adds it to the FSM, but does nothing else. We chose to not issue a debug message, much less a warning in that case - it seems rarely useful, and quite likely to scare people unnecessarily. For now empty pages aren't added to the VM, because standbys would not re-discover such pages after a promotion. In contrast to other sources for empty pages, there's no corresponding WAL records triggering FSM updates during replay. Author: Andres Freund Reviewed-By: Tom Lane Discussion: https://postgr.es/m/20181219083945.6khtgm36mivonhva@alap3.anarazel.de
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/.