Caveat: I'm not an sqllite guru
But usually the problem with rowid in databases is that it is not guaranteed to
remain consistent and will change when the physical location of records is
changed through internal housekeeping. That said it is often a very good and
efficient way of accessing data with integrity guaranteed provided you are
using it within a single read consistent query and not storing its value for
reuse.
Rgds,
Rob.
From: johannes hanika [mailto:hana...@gmail.com]
Sent: 20 October 2013 08:36
To: Pascal Obry
Cc: darktable-devel
Subject: Re: [darktable-devel] problem with styles
oh. my understanding of the sqlite docs is that rowid is just an internal thing
that we shouldn't rely on because they reserve the right to change what it does
between versions etc?
i'm totally for an additional id in this case.. there is some sql update path
somewhere around control_init() (control.c:690) maybe it's possible to add an
additional column id = rowid in case there is no id col yet.
-jo
On Sun, Oct 20, 2013 at 8:23 PM, Pascal Obry
<pas...@obry.net<mailto:pas...@obry.net>> wrote:
The problem is the following.
The styles are numbered after its rowid (table styles)
The styles items have a styleid referencing the style above.
When a style is removed the rowid are non continuous, that is:
sqlite> select rowid,* from styles;
1|red|
3|blue|
4|violet|
The rowid is style referencing the proper items.
But if the database is vacuumed, the those rowid are continuous and not
referencing the proper style:
sqlite> vacuum;
sqlite> select rowid,* from styles;
1|red|
2|blue|
3|violet|
I think it is a mistake to use the rowid as an index. In fact it is the
only cases on dt where this is done.
The proper solution would be to introduce an id into the styles table.
Not sure how to handle this migration path though.
Idea?
--
Pascal Obry / Magny Les Hameaux (78)
The best way to travel is by means of imagination
http://v2p.fr.eu.org
http://www.obry.net
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