I looked at the database attached to the ticked and noticed that the table
contains NULL rowids as well duplicate rowids. This should happen as SQLite
usually rejects duplicate rowids with a constraint error.
When I run this query:
select rowid, count() from ndxparamvalues_localizedstring
group by rowid
order by 2 desc
I get the following results:
rowid count ()
NULL 1759
10 1601
20 1341
30 1281
40 1254
50 1200
... more results follow, 3161 in total.
So I wonder how you managed to fill your database with duplicate rowids?
I also wonder if this is somehow related to your "problem"?
Ralf
>I've only found one reference to slower queries with the DISTINCT/GROUP
>BY optimization that went in back in November for 3.5.3 and later. I
>would have expected more given the number of our queries causing problems.
>
>The problem as I wrote in ticket 3128
><http://www.sqlite.org/cvstrac/tktview?tn=3128> appears to be with
>queries that use DISTINCT and LIMIT. If the query is somewhat slow (in
>my example, it's joining several large tables), the new DISTINCT
>(implemented in the code as GROUP BY) can be much, much slower because
>it (apparently) collects all or most of the rows before applying GROUP
>BY, even when there's a LIMIT. Before the change (3.5.2 and earlier),
>DISTINCT was aided by the LIMIT quite a bit. In my example, the query
>takes around 0.02 seconds in 3.5.2 and earlier, 3.1 seconds in 3.5.3 and
>later.
>
>Has anyone else seen similar behavior? If so, have you found a
>workaround? My workaround is actually a patch to the source to disable
>the optimization when a LIMIT is given, though there might be cases
>where this is undesirable (like maybe cases where the table has indices
>that can be used by GROUP BY and the LIMIT is sufficiently high).
>
>Brad Town
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