Thank you Dan,
I will try that.
Mikhail Berman
-----Original Message-----
From: Dan Nelson [mailto:dnelson@stripped]
Sent: Wednesday, May 03, 2006 5:29 PM
To: Mikhail Berman
Cc: Chris White; mysql@stripped
Subject: Re: Q2. Is there anything could be done to speed up this query
In the last episode (May 03), Mikhail Berman said:
> Thank you, Chris
>
> But the table is indexed on the field you are referring to and the
> other one the query, which is evident from this:
>
> > KEY `prdadadx` (`price_data_date`),
> > KEY `prdatidx` (`price_data_ticker`)
These are two separate keys, though, and your query is doing a GROUP BY
across both fields, so neither of those keys would be useful (mysql
would have to do a random record lookup for each row to fetch the other
field). Try an index on (price_data_ticker, price_data_date). Since
your query only references those fields, mysql should be able to return
your results just by scanning the index.
--
Dan Nelson
dnelson@stripped
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