Subject Re: [ib-support] SELECT Order by DESC
Author Helen Borrie
At 01:17 PM 20-05-02 +0200, Balázs Szakály wrote:
>Why cannot use FB any index on select with desc order?

I guess to "capsize" an index, FB would have to have indexes on indexes,
which it doesn't. FB data are not physically stored in any order. You
create indexes to "describe" the orderings you want.

>Select * from TTT order by FFF desc
>There is an index to fff but not desc order. Why cannot use in this
>So, i need to create 2 indexes to all table, where i need desc order
>with high response time.

Yes. Create descending indexes for descending sorts, use your ascending
indexes (default) for ascending sorts.


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Firebird Open SQL Database · ·