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From:Krishna Chandra Prajapati Date:September 2 2008 6:00pm
Subject:Re: Impossible WHERE in explain
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Thanks a lot. I got the answer. "Impossible where in explian" comes when the
query doesn't make any sense to the mysql optimizer.

Please visit the link below for more details.

http://books.google.co.in/books?id=sgMvu2uZXlsC&pg=PA94&lpg=PA94&dq=impossible+where+noticed+after&source=web&ots=fsQxHni1Ey&sig=k449ikPwIi4O-11whdD9MuNdbhM&hl=en&sa=X&oi=book_result&resnum=5&ct=result#PPA94,M1

On Tue, Sep 2, 2008 at 6:18 AM, Martin Gainty <mgainty@stripped> wrote:

>  The key_len column indicates the length of the key that MySQL decided to
> use. The length is NULL if the key column says NULL. Note that the value
> of key_len allows you to determine how many parts of a multiple-part key
> MySQL will actually use.
>
> i do not know the definition of parameter 'ken_len'
>
> Martin
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>
> > Date: Tue, 2 Sep 2008 02:05:00 +0530
> > From: prajapatikc@stripped
> > To: brenttech@stripped
> > Subject: Re: Impossible WHERE in explain
> > CC: mysql@stripped
>
> >
> > I have already tried. It's not working.
> >
> > On Tue, Sep 2, 2008 at 1:55 AM, Brent Baisley <brenttech@stripped>
> wrote:
> >
> > > It might be because you you are comparing user_id to a string, when the
> > > field type is a decimal. Drop the quotes around the user_id search
> value and
> > > see if that works.
> > >
> > > Brent Baisley
> > >
> > >
> > > On Sep 1, 2008, at 3:59 PM, Krishna Chandra Prajapati wrote:
> > >
> > > Hi,
> > >>
> > >> In the query below explain gives 'Impossible WHERE noticed after'.
> what
> > >> does
> > >> this mean.
> > >>
> > >> CREATE TABLE `user_cookie` (
> > >> `user_id` decimal(22,0) NOT NULL default '0',
> > >> `param` varchar(128) NOT NULL default '',
> > >> `value` varchar(128) default NULL,
> > >> PRIMARY KEY (`user_id`,`param`),
> > >> CONSTRAINT `fk_user_cookie` FOREIGN KEY (`user_id`) REFERENCES
> > >> `user_info` (`user_id`) ON DELETE NO ACTION ON UPDATE NO ACTION
> > >> ) ENGINE=InnoDB DEFAULT CHARSET=latin1
> > >>
> > >> SELECT VALUE FROM user_cookie WHERE USER_ID = '10538485' AND PARAM =
> > >> 'TIMEOUT' table |type |possible_keys |key | ken_len|ref | rows| 1
> > >> |SIMPLE | | | | | |Impossible WHERE noticed afte
> > >> --
> > >> Krishna Chandra Prajapati
> > >>
> > >
> > >
> >
> >
> > --
> > Krishna Chandra Prajapati
>
>
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-- 
Krishna Chandra Prajapati
MySQL DBA,
Ed Ventures e-Learning Pvt.Ltd.
1-8-303/48/15, Sindhi Colony
P.G.Road, Secunderabad.
Pin Code: 500003
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Email-id: prajapatikc@stripped

Thread
Impossible WHERE in explainKrishna Chandra Prajapati1 Sep
  • Re: Impossible WHERE in explainBrent Baisley1 Sep
    • Re: Impossible WHERE in explainKrishna Chandra Prajapati1 Sep
      • RE: Impossible WHERE in explainMartin Gainty2 Sep
        • Re: Impossible WHERE in explainKrishna Chandra Prajapati2 Sep
  • Re: Impossible WHERE in explainJim Lyons1 Sep