Re: Seeking a faster response to Where EXISTS or WHERE IN

how about:

select a.* from filea a

join (select disinct field_aa from from file_B) b

on a.field_a = b.field_aa

(syntax may not be exact)

This might be quicker.

Paul

On 2016-12-22 09:22, D Freinkel (a4g) wrote:

I am doing extracts from files based on records in file A

Select * from FILE_A where field_A in (Select FIELD_AA from FILE_B).

Or

Select * from FILE_A where field_A exists i (Select FIELD_AA from FILE_B
where FIELD_A = FIELD_B).

File_A and FILE_B both have about a million records.

Problem:

When running the program it takes a few minutes to build the sub-select.

Using CHAINS is instant, but I would prefer to use SQL.

Can anyone help with performance improvements?

TIA

Darryl Freinkel

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