Re: [Tracker] FTS4 branch review

[Martyn Russell <martyn lanedo com>]

On 15/02/13 10:45, JÃrg Billeter wrote:
> Hi Martyn,

Hello,

> thanks for testing this.

No problem.

> On Thu, 2013-02-14 at 19:29 +0000, Martyn Russell wrote:
> > Test B (FTS4)
> > =============
> >
> > -rw-r--r-- 1 martyn martyn  25M Feb 14 18:33 meta.db
> > -rw-r--r-- 1 martyn martyn 1.5M Feb 14 18:34 meta.db-wal
>
> > Test B (0.14.5)
> > ===============
> >
> > -rw-r--r-- 1 martyn martyn  24M Feb 14 18:49 meta.db
> > -rw-r--r-- 1 martyn martyn 9.8M Feb 14 18:53 meta.db-wal
>
> > Conclusions:
> > ============
> >
> > For Test B, the database size for Tracker with FTS4 is much smaller. So
>
> The size of the WAL journal is not directly related to the database
> size. The main database file is nearly the same size, though, so the new
> setting doesn't appear to have had a big impact in this test.

Indeed. I did wonder why the WAL journal was different though.

> > while we might be indexing more words (i.e. those which are smaller than
> > 3 characters), we're still a smaller database. The reason for this could
> > be that we were previously duplicating data (Carlos can confirm this)
> > and now we're using the data only once. Either way, a smaller database
> > is always preferred if we can have it.
>
> We weren't duplicating data before either. Upstream fts3 was, but
> getting rid of that duplication was one of the major reasons to use our
> own version of fts3.

Yea, I checked this with Carlos this morning because I wasn't sure. 
Thanks for confirming. He said the same thing.

Carlos did note not seeing so much of a difference in his tests, but I 
would imagine it scales with more data.

Thanks JÃrg,

--
Regards,
Martyn

Founder and CEO of Lanedo GmbH.