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From:Marc De Caluwé Date:April 9 1999 1:59pm
Subject:Performance.
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Hi all,

Until now I was only using M$ Access databases, but I want to change to
another database for reasons of performance (and to Linux for reasons of
money).
I already exported two Access tables to MySQL.

One is called LinkedInfo: 600.000 records, 8 columns with indexes on
Record_ID and Link_ID.

The other one JoinedLinkedInfo: about 2 million records, 6 columns with
indexes on Link_ID, Field_ID and ValueNum.

When I'm doing the following query:

SELECT SUM(JoinedlinkedInfo.ValueNum) AS Amount, LinkedInfo.Record_ID FROM
(LinkedInfo LEFT JOIN JoinedLinkedInfo ON LinkedInfo.Link_ID =
JoinedLinkedInfo.Link_ID) WHERE (JoinedLinkedInfo.Field_ID=21) GROUP BY
LinkedInfo.Record_ID;

mySQL gives me the result (84.245 records) after... 2 hours and 59 minutes.

The same query (on a similar pc) in Access takes about 6-7 minutes.
What am I doing wrong???


Marc

Thread
Performance.Marc De Caluwé9 Apr
Re: Performance.Fred Lindberg9 Apr
  • RE: Performance.Marc De Caluwé13 Apr
    • Re: Performance.Sasha Pachev13 Apr
RE: Performance.Marc De Caluwé18 Apr
  • RE: Performance.Michael Widenius19 Apr