in reply to Re^3: For a better efficiency and speed question!
in thread For a better efficiency and speed question!

What is wrong with this code?
=code
my $sql = $dbh->exec_select("
SELECT acc, name,date
FROM mytable
WHERE name <> ''
AND ((date + 1 YEAR) >= (CURRENT_DATE))
AND ((date + 1 YEAR) < (CURRENT_DATE + 240 DAYS))
AND controlnum IN ('12345','8877788','23334455','223445988','222339000
+','2222333','223475699','22339668','2223999','009999','11220000','777
+66','88776'
,'9988888','11223756','22388577','9998888','998888','77665555','999988
+8','88877777','666555555','88777766666','112223333','9998877','998887
+7'
,'888777666666','00988777','887777654')
and date between '2010-11-11' and '2011-11-11' order by date desc");
=cut

[download]
If you show where you see the error it would help! Thanks

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Re^5: For a better efficiency and speed question!
by pvaldes (Chaplain) on Oct 04, 2011 at 18:11 UTC

    Nothing wrong really, but you ask for efficiency and speed, and anything counts...

    You use: AND ((date + 1 YEAR) < (CURRENT_DATE + 240 DAYS))

    Let's see the algoritm. For each record you sum 365 to date and remember this number, then you sum 240 to current date and save this to a new var somewhere in the memory, then you compare both numbers

    I'm suggesting this instead: AND ((date + 125 DAYS) < CURRENT_DATE)

    Now for each record you sum 125 to date and compare this with current date. You are creating a new var, not two.

    Thus you need less memory and is also a little less demanding operation for the CPU. Nothing to care for when you have a few sums but in this context could suppose one advantage

[reply]
[d/l]
[select]
      And now for the sql question, if not done yet, you should index or reindex your table (the controlnum field is a good candidate to be in the index) and probably use some views in order to check only a part of your table, and simplify the work to perl.
[reply]
        I didn't understand your logic behind sum of 125 to "date"??
[reply]

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