| Subject | Re: Compound Index |
|---|---|
| Author | pokka_chi |
| Post date | 2007-05-03T06:23:35Z |
--- In firebird-support@yahoogroups.com, "Adam" <s3057043@...> wrote:
then, 1.5.4 is the version with some bug fixes in 2.0 back ported to
1.5. Not sure if this is related.
I think this might be related to MGA. When FB receives my SQL
statement (select first 10 * from MY_TABLE where Column1 > 100 order by
Column1, Column2), it doesn't use the parameter for FIRST. So it will
tag all the 89901 records with my transaction id. This essentially is
equivalent to a table scan. The parameter for FIRST is only used in
the output stage to restrict the number of records returned.
PK
>I've tried 1.5.4 and found the result to be similar to 2.0.1. But
> I don't have time today to upgrade my laptop to test this problem,
> perhaps you could try 1.5 to see if this is a new issue in the 2.x
> optimiser.
>
then, 1.5.4 is the version with some bug fixes in 2.0 back ported to
1.5. Not sure if this is related.
>I thought so. I have a hypothesis. Perhaps Ann or Helen can comment.
> It certainly should be sub-second.
>
I think this might be related to MGA. When FB receives my SQL
statement (select first 10 * from MY_TABLE where Column1 > 100 order by
Column1, Column2), it doesn't use the parameter for FIRST. So it will
tag all the 89901 records with my transaction id. This essentially is
equivalent to a table scan. The parameter for FIRST is only used in
the output stage to restrict the number of records returned.
PK