Hi Thomas,

I am running classic firebird 2.1, but I don't think its GC as I ran both a
sweep and a backup and still got the same, longer, time

On 29 July 2013 16:44, Thomas Steinmaurer <ts@...> wrote:

> **
>
>
> > I'm trying to understand why there is such a large difference in runtime
> > between these 2 situations.
> > firebird 2.1.5
> >
> > run a script to create 130000 records in a table, then use it for a
> while.
> > Which means
> > updates to some fields within that table.
> >
> > run "select * from table", takes around 4.8 seconds
> >
> > do a backup & restore of the database
> >
> > run "select * from table", takes around 0.3 seconds
> >
> > t
> > he plan shows a natural scan in both cases, no other database usage
>
> If you are using an Firebird architecture with cooperative garbage
> collection, e.g. Classic in Firebird 2.1 or Classic/SuperClassic in
> Firebird 2.5, then the difference in execution time might be garbage
> collecting out-dated record versions.
>
> MON$RECORD_STATS might give you a clue if a statement is actively
> involved in garbage collection with Classic/SuperClassic. Due to the
> nature of the MON$ tables being an activity snapshot for a certain
> point-in-time, you may miss the statement.
>
> The Trace API will give you this information for continuous statement
> execution, but as you might know, the Trace API has been added in
> Firebird 2.5, which aren't using.
>
> --
> With regards,
> Thomas Steinmaurer
> http://www.upscene.com/
>
> Professional Tools and Services for Firebird
> FB TraceManager, IB LogManager, Database Health Check, Tuning etc.
>
>
>



--
Nick Upson, Telensa Ltd


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