c4afdca4c2
hash indexes keep entries sorted by hash value. First, the original plans for concurrency assumed that insertions would happen only at the end of a page, which is no longer true; this could cause scans to transiently fail to find index entries in the presence of concurrent insertions. We can compensate by teaching scans to re-find their position after re-acquiring read locks. Second, neither the bucket split nor the bucket compaction logic had been fixed to preserve hashvalue ordering, so application of either of those processes could lead to permanent corruption of an index, in the sense that searches might fail to find entries that are present. This patch fixes the split and compaction logic to preserve hashvalue ordering, but it cannot do anything about pre-existing corruption. We will need to recommend reindexing all hash indexes in the 8.4.2 release notes. To buy back the performance loss hereby induced in split and compaction, fix them to use PageIndexMultiDelete instead of retail PageIndexDelete operations. We might later want to do something with qsort'ing the page contents rather than doing a binary search for each insertion, but that seemed more invasive than I cared to risk in a back-patch. Per bug #5157 from Jeff Janes and subsequent investigation. |
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| contrib | ||
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| GNUmakefile.in | ||
| Makefile | ||
| README | ||
| README.CVS | ||
| aclocal.m4 | ||
| configure | ||
| configure.in | ||
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: 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/.