Comments on: KDE and internal storage

By: aexl

aexl — Thu, 24 Dec 2009 11:33:59 +0000

What if…

amarok stored its metadata in nepomuk AND made its great tagging frontend usable to tag ANY content. Imagine Amarok tag&search for openoffice metadata!

By: Jim

Jim — Thu, 02 Oct 2008 01:08:44 +0000

I personally think a full SQL server should be a gimmy in a modern OS. MySQL is common enough, respected enough, and really isn’t all that terrible to have loaded all the time for the typical desktop capable system.

I have a music collection large enough that it makes Amarok painful if used with a sqlite backend. So, I use MySQL with Amarok instead. I don’t notice its footprint much at all. I do notice Amarok and the rest of my system being more responsive when Amarok goes about switching tracks and selecting new tracks to add to a dynamic playlist.

It would be cool to see more applications using a full sql database and take advantage of some of the sophisticated preformance enhancing features that come for free in a more complete database engine (such as key caching).

By: kanenas

kanenas — Mon, 29 Sep 2008 22:47:45 +0000

To add to the optimizations that b0b said:

Choose a better page size when creating the database (default 1024 is too small)
PRAGMA page_size = 4096 (or 8192)

By: b0b

b0b — Mon, 29 Sep 2008 18:16:32 +0000

When using sqlite, appart for using indexes and writing optimized requests, here’s 2 easy optimization that will make it faster:

- enclose the more request that you can in a BEGIN; … COMMIT; block
- use “PRAGMA SYNCHRONOUS=OFF” to delay write on disk.

By: jstaniek

jstaniek — Mon, 29 Sep 2008 15:36:19 +0000

@Jos van den Oever
“There already is QSql to abstract away the database access. It still leaves the sql incompatibilities though. Something like hibernate would be really nice.”

There’s KexiDB, and now Predicate (in development)…

By: Ian Monroe

Ian Monroe — Mon, 29 Sep 2008 13:21:24 +0000

@Miguel: both akondai and Amarok will start the server for you. You’ll hardly know its there. :)

By: Ian Monroe

Ian Monroe — Mon, 29 Sep 2008 13:19:44 +0000

@Kevin don’t you see what we’re loosing from supporting multiple backends? It lessens the potential for a nice desktop-wide database – Amarok is never going to support both mysql and postgresql, we don’t want to support multilple SQL dialects.

And you really get nothing in return. Any user only needs one backend at a time. Its like what Amarok figured out with multiple sound engines in 1.2-1.3: they give headaches but few benefits.

By: Ian Monroe

Ian Monroe — Mon, 29 Sep 2008 13:15:48 +0000

@Kanenas I wouldn’t doubt this really. But we aren’t database experts, we don’t know how to optimizer our queries outside of adding a few indexes and we certainly don’t know how to hack sqlite. Given that many distros have Amarok using system sqlite I wonder if its even possible.

By: Kanenas

Kanenas — Mon, 29 Sep 2008 11:44:02 +0000

About mysql vs sqlite:
In my experience sqlite outperforms mysql when one knows what he is doing. Sqlite out of the box is considerably conservative towards the safe side. Slightly tweeking sqlite can make large differences in speed.

Please before judging sqlite do a little research beforehand. Mysql sacrifices a lot of safety to be fast (notice the difference in the number of fsyncs these databases do out of the box). By sacrificing a little safety, sqlite can outperform mysql.

By: Kevin Krammer

Kevin Krammer — Mon, 29 Sep 2008 11:37:42 +0000

@Miguel: it is, since it is using Qt’s database abstraction layer and only very few DB specific parts.

I.e some people are working on (or have already completed) the bits for supporting postgres

http://techbase.kde.org/Projects/PIM/Akonadi#Which_DBMS_does_Akonadi_use.3F

@Anon
http://techbase.kde.org/Projects/PIM/Akonadi#Why_not_use_sqlite.3F

@Lee
Qt3 has explicit database widgets, even in designer, and Qt4 has database bound models for its model/view framework