Thanks, Ann!

Increasing the page cache helped a lot!

I´m using UUIDs because they are easier to work with bi-diretional replication. I think they are worth the price to pay in performance loss, at least in my case (not too many inserts daily).

I used sequences and intervals before, but they still require some configuration.

Regards,

Fabiano

--- In firebird-support@yahoogroups.com, Ann Harrison <aharrison@...> wrote:
>
> Fabiano,
>
>
> > I had to insert 300.000 records in a table with no indices or triggers
> > except the primary key, which is type "char(16), character set octets".
> >
> > With the primary key, it took 40 minutes to insert all records.
> >
> > Removing the primary key, it took 1m40s to insert all records.
> >
> > Both tests were done using a just restored database, forced-writes off,
> > firebird 2.5, and the same machine.
> >
> > Is this difference expected? Maybe it is related to the type of the primary
> > key?
> >
>
> If your primary key is a UUID (likely, given the type) and you're using
> classic, increase the page cache by a lot. The problem is that UUIDs are
> created in random order, so inserts occur at random places in the index. If
> the particular index page needed has been dropped from the cache, it has to
> be read again. Keys generated by sequences (aka generators) compress very
> well as well as avoiding random access to index pages. Of course,
> generators are not unique across machines, so if you require a cross-machine
> unique value you must either use a compound key <generated value> <machine
> id> or set the generators on different machines to different ranges.
>
> Good luck,
>
> Ann
>
> A second problem with using UUIDs as index keys is that they compress much
> less well than sequences.
>
>
> [Non-text portions of this message have been removed]
>