Re: [Tracker] PATCH: Don't use the count_changes PRAGMA in SQLite, it is deprecated

[Martyn Russell <martyn lanedo com>]

Realised, I didn't CC the list.

Also, sorry Jonatan, but I forgot to assign authorship to your commit :(

And GNOME's git doesn't appear to allow me to change that easily. If 
anyone in the GNOME community knows how to do this to origin (upstream), 
let me know.

Thanks,


On 19/07/13 14:41, Martyn Russell wrote:
> On 19/07/13 08:13, Jonatan Pålsson wrote:
> > On 18 July 2013 17:56, Martyn Russell <martyn lanedo com> wrote:
> > Here's a short snippet demonstrating the effects of the PRAGMA on
> > SQLite 3.7.9, which should show that removing the PRAGMA doesn't
> > change the behavior of Tracker (I also ran Tracker with the new
> > PRAGMA, of course, but I think this is a more concrete example). It
> > should be noted that the following snippet most likely corrupts the
> > Tracker database, so don't run it on a database with any important
> > information in it. I will actually corrupt the snippet a bit to
> > prevent people from just cutting and pasting for the fun of it.
> >
> > $ cat /tmp/pragma.py ; echo ; echo "Output:" ;
> > LD_LIBRARY_PATH=/tmp/sqlite_install/lib python /tmp/pragma.py
> > import sqlite3
> >
> > def pragma(sql):
> >      db = sqlite3.connect("/home/jonatan/.cache/tracker/meta.db")
> >      c = db.cursor()
> >      if sql:
> >          c.execute(sql)
> > !! Warning - Don't actually run this code, it is bad for your
> > database. !!
> >      res = c.execute("insert into Resource values ('1008040', 'phony')")
> >      r = res.fetchone()
> >      db.close()
> >      return r
> >
> > p1 = pragma("PRAGMA count_changes = 1")
> > p2 = pragma("PRAGMA count_changes = 0")
> > p3 = pragma(None)
> > print "p1: %s\np2: %s\np3: %s" % (p1,p2,p3)
> > if (p2 == p3):
> >      print "Default behavior equals PRAGMA count_changes = 0"
> > print "SQLite library version: %s" % sqlite3.sqlite_version
> >
> > Output:
> > p1: (1,)
> > p2: None
> > p3: None
> > Default behavior equals PRAGMA count_changes = 0
> > SQLite library version: 3.7.9
>
> Thanks for the example.
>
> I was looking in the source for SQLite3, but couldn't find it in a short
> time. So thanks.
>
> > > Before I commit, I want to make sure the pragma wasn't deprecated
> > > before the
> > > version we depend on (3.7.9) and the default is correct.
> > >
> > > Did you verify this?
> >
> > The snippet above should serve as verification of the correctness of
> > the defaults, but I am actually unable to verify when the PRAGMA was
> > deprecated. I can't find it in any release notes, and the commit
>
> Yea, I was looking in the sources and git log (mirror) for signs of this
> and couldn't see anything. Even the website side of things (which used
> to be in the source < v3) is no longer in the code base so I can't go on
> when the documentation was updated either :/
>
> > history of the project does not appear to be searchable easily. Is the
>
> Yea, this was my problem too.
>
> > fact that the semantics are correct for version 3.7.9, and the fact
> > that the PRAGMA is deprecated in the current documentation enough?
>
> Yes, thanks for providing the details here.
>
> > I will look a bit more for the deprecating commit, and post an update
> > if I find it!
>
> I've committed this patch.
> Thanks again :)


--
Regards,
Martyn

Founder and CEO of Lanedo GmbH.