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Jim Hu wrote:
$wgDBtransactions gets set to true if using InnoDB
tables. Is there
an advantage to using InnoDB tables?
The disadvantage is that with MySQL there is a file, ibdata1, that
seems to grow endlessly if InnoDB tables are used. See
We're wondering if we should just convert everything to MyISAM. Any
MyISAM tables are subject to a much higher likelihood of data
corruption, and cannot be read consistently (eg for backups) without
locking the database.
You may notice that the majority of complaints about corrupt tables
involving MediaWiki are about the 'searchindex' table, which is created
as MyISAM due to the requirements of the fulltext index.
In most wiki situations your database will indeed only grow, so the
table space not reclaiming disk space on deletions is usually not a
problem. In the wiki, all editing history is retained, and the space
from the rare small records that are actually removed will simply be
taken up by further edits.
If you for some reason want to import a lot of data, then delete it all,
then never work with any database data ever again, well... that's pretty
weird. ;) But as suggested in your link you can use per-table InnoDB
spaces in recent versions of MySQL, or you can use the more fragile
MyISAM tables, or you can "defragment" the table space by dumping it
out, deleting the space, and reimporting it.
In some situations MyISAM tables may also be faster, which could be
useful for certain kinds of statistical or other use.
- -- brion vibber (brion @ pobox.com
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