980224b4a2
Solely relying on a relation's reltuples/relpages estimate to size the Bloom filters used by amcheck verification makes verification less effective when the estimates are very stale. In extreme cases, verification options that use Bloom filters internally could be totally ineffective, without users receiving any clear indication that certain types of corruption might easily be missed. To fix, use RelationGetNumberOfBlocks() instead of relpages to size the downlink block Bloom filter. Use the same RelationGetNumberOfBlocks() value to derive a minimum size for the heapallindexed Bloom filter, rather than completely trusting reltuples. Verification will still be reasonably effective when the projected/estimated number of Bloom filter elements is at least 1/5 of the final number of elements, which is assured by the new sizing logic. Reported-By: Alexander Korotkov Discussion: https://postgr.es/m/CAH2-Wzk0ke2J42KrNYBKu0Xovjy-sU5ub7PWjgpbsKdAQcL4OA@mail.gmail.com Backpatch: 11-, where downlink/heapallindexed verification were added. |
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| README.git | ||
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README
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/.