From: Jin Hui
Date: March 29 1999 6:38am
Subject: RE: Question about query
List-Archive: http://lists.mysql.com/mysql/1123
Message-Id: <50E89D0739DBD1119B5500A0C932C7E6881419@exchsrv.ubisoft.com.cn>
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1. The first query was wrong, it should be
	select id from atable where truncate(c1/1000000, 0) = 321

2. I cannot do a testing. Because I am running the database on a web
hoster's shared server. The testing time results are very different for the
same query. I cannot compare them.

3. I also want to know if there's any other faster way to do integer
division like the / in c. I am using truncate.

4. Because the server space is limited. I only can make necessary index. I
want to know if the index on c1 or c1/1000000 is helpful to speed.

I need some suggestion from someone has such experience. Thanks for any
help!

Best Regards,
Jin Hui


> -----Original Message-----
> From:	Ed Carp [SMTP:erc@stripped]
> Sent:	Monday, March 29, 1999 1:52 PM
> To:	Jin Hui; mysql@stripped
> Subject:	Re: Question about query
> 
> >I have a query like
> >select id from atable where truncate(c1/1000000) = 321
> >
> >I learned that following query has the same function
> >select id from atable where c1 like '321______'
> >
> >I'd like to know which is faster. Or anyone know how to do integer
> division
> >in MySQL faster.
> >
> >And if I make a index on c1 or a index on c1/1000000, which index will
> >increase the query speed, or none index is helpful.
> 
> 
> I hate to be a curmudgeon (again) but wouldn't it be easier and faster to
> test it on your own machine than posting to a mailing list and essentially
> asking someone else to do your work for you?
> 
> Indexing a field is generally always faster, but this depends on your
> application.  Again, test it on your own machine with a big recordset and
> time it to see which is faster.
> 
> 
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