Hi again, Rafael!

> The Feribird plan for this select is:
>
> PLAN SORT (JOIN (I INDEX (FK_BS_IDX_COD_GRP,BS_IDX_COD_BASE_IDX),T
> INDEX (PK_BS_TRM)))
>
> This select takes 23.294,00 ms to execute with GROUP BY T.TRM clause
> and 30,00 ms without GROUP BY TRM clause. So, I'm trying to do
> Firebird to use BS_TRM_TRM_IDX for T.TRM column too. I'm trying the
> following plan:

30 ms? Is that for returning all records or just a few records? Using
GROUP BY forces fetching everything, whereas without any GROUP BY or
DISTINCT that is not neccessary. So check how long time each query
takes to fetch the entire result set.

> PLAN JOIN( T ORDER BS_TRM_TRM_IDX, T INDEX (PK_BS_TRM), I INDEX
> (FK_BS_IDX_COD_GRP))

To speed things up, I'd rather check the selectivity for the indexes
used. I assume PK_BS_TRM is unique, so that is a good index. But what
about FK_BS_IDX_COD_GRP and BS_IDX_COD_BASE_IDX, are they selective or
does most of the records match your comparison? How big are your
tables anyway?

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