Re: [Firebird-devel] Firebird feature requests

[Ann W. H. <aha...@ib...>]

Jim Starkey wrote:
>>>>     
> 
> Excuse me, but I don't understand who said that indexes should not be 
> used for inequalities or why he or she would say that.  Unless 100% of 
> the records meet the selection critereon, the indexed version will 
> always be faster, and even if 100% of the records are selected, the cost 
> of the index scan is small compared to fetching the actual records.  Am 
> I missing something here?
> 

Yes... the process of building the data for the query, includes this step:

4) Simulate some past table activity (important! do not skip this step)
update mytable set status = 3 where status = 1;
update mytable set status = 1 where status = 2;
update mytable set status = 2 where status = 3;
commit;


Those updates create back versions and index entries.  The result is 
that every record has a version that has the value 1.  Most of them are 
old versions and the garbage collection may also affect the query timings.

Regards,


Ann