Re: [Firebird-devel] Count(*) faster without index ?

[Adam G. <s30...@ya...>]

"Derryck welas" wrote:

> Hi ,
> 
> I always assumed using an index works faster ( well  it is faster
> when the count volume is low).
> 
> but this case proved otherwise (when the counted volume gets very
> high).


Derryck,

How did you test this? You need to remember that caching happens both
within Firebird and also your operating system, so the query that runs
first will have to wait for disks, whereas the query that runs second
can often just read from the cache.

To get an honest profile, use two copies of the database (as two
different aliases). Run one test against one database and the other
against the other database.

Adam