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From:Zachary Stern Date:February 26 2013 9:16pm
Subject:Re: data loss due to misconfiguration
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It's InnoDB but it's not just about the number of rows.

The data literally isn't there. It's like rows at the end are being
dropped. We have a frontend that queries and shows the data, but it ends up
missing results.

I've asked the devs to review the code to see if their  could be deletions
anywhere, but according to them, there's nothing.


On Tue, Feb 26, 2013 at 4:14 PM, Rick James <rjames@stripped> wrote:

> If it is MyISAM and there is some form of corruption, you might get the
> symptom you see.  Do CHECK TABLE.
>
> information_schema has the same "flaw" in row count as SHOW TABLE STATUS
> for InnoDB.
>
> > -----Original Message-----
> > From: Stillman, Benjamin [mailto:BStillman@stripped]
> > Sent: Tuesday, February 26, 2013 11:04 AM
> > To: Zachary Stern; mysql@stripped
> > Subject: RE: data loss due to misconfiguration
> >
> > Are you actually querying the table (select count(*) from table_name),
> > or just the stats (show table status)? Is the table Innodb?
> >
> > If  you're using Innodb and aren't doing a select count (or other
> > select query) on the table, then yes you'll have varying results. This
> > is because unlike MyISAM, Innodb does not keep a count of the records.
> > Using show table status gives just an estimation. This would be my
> > first path of investigation.
> >
> > http://dev.mysql.com/doc/refman/5.5/en/show-table-status.html
> >
> > "The number of rows. Some storage engines, such as MyISAM, store the
> > exact count. For other storage engines, such as InnoDB, this value is
> > an approximation, and may vary from the actual value by as much as 40
> > to 50%. In such cases, use SELECT COUNT(*) to obtain an accurate
> > count."
> >
> >
> >
> > -----Original Message-----
> > From: Zachary Stern [mailto:zs@stripped]
> > Sent: Tuesday, February 26, 2013 12:42 PM
> > To: mysql@stripped
> > Subject: data loss due to misconfiguration
> >
> > Is such a thing possible? There are no errors or issues, but we can
> > query a table, get X number of rows, query it later, and all of the
> > sudden be missing a thousand rows.
> >
> > I know this isn't much to go on, but I'm not even sure what information
> > to provide. Will be happy to give anything you guys might be able to
> > think of.
> >
> > TIA.
> >
> > -Zachary
> >
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>


-- 

zachary alex stern I systems architect

o: 212.363.1654 x106 | f: 212.202.6488 | zs@stripped

60-62 e. 11th street, 4th floor | new york, ny | 10003

www.enternewmedia.com

Thread
data loss due to misconfigurationZachary Stern26 Feb
  • RE: data loss due to misconfigurationBenjamin Stillman26 Feb
    • RE: data loss due to misconfigurationRick James26 Feb
      • Re: data loss due to misconfigurationZachary Stern26 Feb
        • Re: data loss due to misconfigurationReindl Harald26 Feb
          • Re: data loss due to misconfigurationZachary Stern26 Feb
            • Re: data loss due to misconfigurationshawn green26 Feb
              • RE: data loss due to misconfigurationBenjamin Stillman26 Feb