On 19 Jan 2009, at 13:30, Alexandre Benson Smith wrote:

>> It takes roughly 4 seconds to table scan this data source so it
>> appears that this is doing a table scan based on time versus
>> retrieving the unique keys from the index. That makes sense to me
>> when
>> we include a measure, such as in the following, since computing the
>> measure will require touching all the records. But in the above, we
>> are only operating on the key of the index – why touch the data
>> pages?
>>
>
> Because of MVCC indices on Firebird are dirty, the have no
> transactional
> context, so the negine needs to go to the records (data pages) to
> see if
> an index is visible or not to a given transaction.

This is an embedded OLAP database, so I was hoping we could fiddle
with the transactional settings.

> There is no way to FB resolve a query just using the index
> information.

I figured, but we needed to know if we were just doing something
dumb. Many thanks.

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