Hi Hemant!

Firebird has to look in the table to even see whether the record is
visible to the current transaction, so you cannot even do a 'select
count' without accessing the table itself.

So the technique you mention is useless on Firebird.

I hope you are using WHERE clauses to limit the returned number of
records. How many of the 20 million records do you want to select and
how selective are the indexes used?

Set

Hemant.Sapre@... wrote:

> Hi,
>
>
>
> We are trying to use the Index Coverage concept (as available in other
> databases) in Firebird. But we are not getting any performance benefits
> with this.
>
>
>
> We are trying to fetch records from a 24 Million record table, and in
> order to avoid the fetch from both index and the actual table, we
> included the required non-key field in the index so that the Firebird
> database does not read the table but fetches data from the index.
> However, there is no improvement in the time taken in both approaches.
>
>
>
> Please let us know if there is any alternative technique of doing this
> OR any special way of declaring the index.
>
>
>
> Thanks and Regards,
>
> Hemant.
>
> Project Leader - Investment Banking Group
>
> PrimeSourcing(tm) "Add Value Reduce Risk"
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