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/.
Tom Lane
authored
These flushes were added in my commit d2896a9e, which added the btree logic that keeps a cached copy of the index metapage data in index relcache entries. The idea was to ensure that other backends would promptly update their cached copies after a change. However, this is not really necessary, since _bt_getroot() has adequate defenses against believing a stale root page link, and _bt_getrootheight() doesn't have to be 100% right. Moreover, if it were necessary, a relcache flush would be an unreliable way to do it, since the sinval mechanism believes that relcache flush requests represent transactional updates, and therefore discards them on transaction rollback. Therefore, we might as well drop these flush requests and save the time to rebuild the whole relcache entry after a metapage change. If we ever try to support in-place truncation of btree indexes, it might be necessary to revisit this issue so that _bt_getroot() can't get caught by trying to follow a metapage link to a page that no longer exists. A possible solution to that is to make use of an smgr, rather than relcache, inval request to force other backends to discard their cached metapages. But for the moment this is not worth pursuing.
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| config | ||
| contrib | ||
| doc | ||
| src | ||
| .dir-locals.el | ||
| .gitattributes | ||
| .gitignore | ||
| COPYRIGHT | ||
| GNUmakefile.in | ||
| Makefile | ||
| README | ||
| README.git | ||
| aclocal.m4 | ||
| configure | ||
| configure.in |