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occurring during a reload, such as query-cancel. Instead of zeroing out an existing relcache entry and rebuilding it in place, build a new relcache entry, then swap its contents with the old one, then free the new entry. This avoids problems with code believing that a previously obtained pointer to a cache entry must still reference a valid entry, as seen in recent failures on buildfarm member jaguar. (jaguar is using CLOBBER_CACHE_ALWAYS which raises the probability of failure substantially, but the problem could occur in the field without that.) The previous design was okay when it was made, but subtransactions and the ResourceOwner mechanism make it unsafe now. Also, make more use of the already existing rd_isvalid flag, so that we remember that the entry requires rebuilding even if the first attempt fails. Back-patch as far as 8.2. Prior versions have enough issues around relcache reload anyway (due to inadequate locking) that fixing this one doesn't seem worthwhile.
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: http://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. Changes between all PostgreSQL releases are recorded in the file HISTORY. 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 http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.