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Re: SQL indices a WC format bump and 1.7

From: Daniel Shahaf <d.s_at_daniel.shahaf.name>
Date: Fri, 2 Sep 2011 19:11:17 +0300

Mark Phippard wrote on Fri, Sep 02, 2011 at 12:02:02 -0400:
> On Fri, Sep 2, 2011 at 11:42 AM, Philip Martin
> <philip.martin_at_wandisco.com> wrote:
> > Hyrum K Wright <hyrum.wright_at_wandisco.com> writes:
> >
> >>   sqlite> select * from sqlite_master where type = 'index' and
> >> tbl_name = 'WCROOT';
> >>   index|sqlite_autoindex_WCROOT_1|WCROOT|8|
> >>   index|I_LOCAL_ABSPATH|WCROOT|9|CREATE UNIQUE INDEX I_LOCAL_ABSPATH
> >> ON WCROOT (local_abspath)
> >>
> >> would both indicate there are two indices on the WCROOT table, though
> >> we only define one.  I believe one of these indices is due to the
> >> UNIQUEness of the local_abspath column.
> >
> > Yes, that's why I think we can delete them.  However we rarely write to
> > these tables so the overhead of having the superfluous index is
> > negligible.  There is no real need to remove them from 1.7 if people
> > would prefer to make a more minimal change for 1.7.
>
> I do not know about SQLite, but in other databases I have worked with,
> the database engine is intelligent enough to not create anything
> superfluous in this sort of scenario where the index you want to
> create already exists.
>

Apparently that isn't the case for SQLite, then. I also remember
playing around with EXPLAIN and explictly seeing two indices being
updated.
Received on 2011-09-02 18:12:01 CEST

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