Database layout: Difference between revisions

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#REDIRECT [[MetaWikiPedia:Database layout]]
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<small>Other languages: [[Help:???????????|??? (ja)]] ...[[Meta:Interlanguage links|''Translate this page!'']]</small>
 
<- [[MediaWiki architecture]]
 
Most data for the wiki is stored in a database. See [[MySQL config]] for setup info.
 
(Some data lives only in the [[MediaWiki file usage|filesystem]], other data is just cached there. Data may also be cached in [[memcached]], but lives permanently in the database.)
 
See in the source: [http://cvs.sourceforge.net/viewcvs.py/wikipedia/phase3/docs/schema.doc?rev=1.2&view=markup schema.doc] and [http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/wikipedia/phase3/maintenance/tables.sql?rev=HEAD&content-type=text/vnd.viewcvs-markup maintenance/tables.sql]
 
Currently we have the following tables:
*[[archive table]] - "deleted" pages
*[[blobs table]]
*[[brokenlinks table]] - links in internal link style to non-existing pages in the same project (see below)
*[[categorylinks table]]
*[[cur table]] - current pages
*[[hitcounter table]]
*[[image table]]
*[[imagelinks table]] tracks usage of images in wikipages (see below)
*[[interwiki table]]
*[[ipblocks table]]
*[[links table]] - links in internal link style to existing pages in the same project (see below)
*[[linkscc table]] - (see below)
*[[math table]]
*[[objectcache table]]
*[[old table]] - old versions of pages
*[[oldimage table]]
*[[querycache table]]
*[[recentchanges table]]
*[[searchindex table]]
*[[site_stats table]]
*[[testac table]]
*[[user table]]
*[[user_newtalk table]]
*[[watchlist table]]
 
==Explanation of the link tables==
 
There are presently three link tables: ''links'', ''brokenlinks'' and  ''imagelinks''. There are a couple of uses for these tables:
* enables "What links here" and "Related changes" to work, looking at incoming or outgoing links
* provides the list of pages that use an image shown on an image's description page
* allows making reports of pages that aren't linked (Orphans, Unused images) or are linked to but don't exist (Most wanted pages)
* slightly speed up page rendering by avoiding individual checks for the existence of each linked page to determine how to render its  link
 
The latest software also adds a 'linkscc' table which caches data from the other three tables. This is used only for speeding rendering.
 
=== Maintenance of link tables ===
If you import data to the cur table and don't [[rebuild link tables|rebuild the links]], you
won't be able to use "[[What links here]]", "[[Related changes]]", "[[Orphans]]",
etc. If you don't want to, well I suppose that's okay... (Brion Vibber)
 
==See also==
*[[Experimental new database schema]] ''22:55, 24 Jul 2003''
*[[Proposed Database Schema Changes]] ''18:19, 23 Dec 2003''
*[[en:Wikipedia:Database queries]]
*[[nl:Wikipedia:SQL opdrachten]]
*[[Database layout]]
*[[Documentation: Developer's Guide]]
 
Next page: [[MediaWiki User's Guide: Installation| Installation]] >
 
 
[[Category:MediaWiki User's Guide]]
[[Category:MediaWiki Development]]

Revision as of 14:11, 28 January 2005

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