PasTim wrote:
> As I understand it custom scan deletes entries and recreates them, even
> though the data has not changed. In the process fragmentation occurs,
> even though the content is the same. Deleting and inserting does not
> necessarily re-use the same blocks. Vacuuming persist.db brought the
> size down from around 440MB to 411MB, even though no music tags have
> changed, and database tweak hard reported only around 3% 'waste'.
>
In your case, based on the logs you posted, the delete of Custom Tag and
Mixed Tag data, which should be the biggest chunk, is deleted using drop
+ create + insert.
In a smaller library, with less than 40 000 rows for a scanning module,
delete will be used and this is also the case in your library for
scanning modules like Rating Tag which produce less rows.
I'm not saying that this explains everything, I'm just saying that if
fragmentation is only caused by delete but not by drop+create+insert,
this could be part of the explanation.
I plan to do some further profiling myself, just have to be able to find
the necessary time...
Erland Isaksson ('My homepage' (http://erland.isaksson.info))
(Developer of 'many plugins/applets (both free and commercial)'
(http://wiki.slimdevices.com/index.php/User:Erland).
If you like to encourage future presence on this forum and/or third
party plugin/applet development, 'consider purchasing some plugins'
(http://license.isaksson.info))
*Interested in the future of music streaming ? 'ickStream - A world of
music at your fingertips'
(http://forums.slimdevices.com/showthread.php?98467-Pre-Announcement-ickStream&p=743516)*.
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