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possibility of shared-inval messages causing a relcache flush while it tries to fill in missing data in preloaded relcache entries. There are actually two distinct failure modes here: 1. The flush could delete the next-to-be-processed cache entry, causing the subsequent hash_seq_search calls to go off into the weeds. This is the problem reported by Michael Brown, and I believe it also accounts for bug #5074. The simplest fix is to restart the hashtable scan after we've read any new data from the catalogs. It appears that pre-8.4 branches have not suffered from this failure, because by chance there were no other catalogs sharing the same hash chains with the catalogs that RelationCacheInitializePhase2 had work to do for. However that's obviously pretty fragile, and it seems possible that derivative versions with additional system catalogs might be vulnerable, so I'm back-patching this part of the fix anyway. 2. The flush could delete the *current* cache entry, in which case the pointer to the newly-loaded data would end up being stored into an already-deleted Relation struct. As long as it was still deleted, the only consequence would be some leaked space in CacheMemoryContext. But it seems possible that the Relation struct could already have been recycled, in which case this represents a hard-to-reproduce clobber of cached data structures, with unforeseeable consequences. The fix here is to pin the entry while we work on it. In passing, also change RelationCacheInitializePhase2 to Assert that formrdesc() set up the relation's cached TupleDesc (rd_att) with the correct type OID and hasoids values. This is more appropriate than silently updating the values, because the original tupdesc might already have been copied into the catcache. However this part of the patch is not in HEAD because it fails due to some questionable recent changes in formrdesc :-(. That will be cleaned up in a subsequent patch. |
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| config | ||
| contrib | ||
| doc | ||
| src | ||
| aclocal.m4 | ||
| configure | ||
| configure.in | ||
| COPYRIGHT | ||
| GNUmakefile.in | ||
| Makefile | ||
| README | ||
| README.CVS | ||
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/.