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Performance Issue

Performance Issue

Performance Issue

I am calling this SQL statement on my Access database using VB. However It is extremely SLOW.


FROM tblMain
WHERE tblMain.[Phone Number] Not In (Select tblSub.[Phone Number] from tblSub) 

Any ideas on how to speed things up?



RE: Performance Issue

Are both Phone Number fields indexed? Are either primary keys?

Hook'D on Access
MS Access MVP 2001-2016

RE: Performance Issue

Do you have a large number of records in tblMain? tblSub?
By 'large', I mean - millions?

---- Andy

There is a great need for a sarcasm font.

RE: Performance Issue

Hi, yes, both indexed and a few hundred thousand in tblMain and a few million in tblSub.



RE: Performance Issue

Is the [Phone Number] unique in tblSub? If not, I would try run a make table query with unique phone numbers and make the phone number primary. Then use the new table rather than tblSub.

Otherwise since there are so many records, I would maybe try batches of records or a LEFT JOIN.

Millions of records in Access will take some time.

Hook'D on Access
MS Access MVP 2001-2016

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