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From:Kevin Hunter Date:July 27 2008 8:31pm
Subject:Re: Adding index to Memory table LOSES ROWS!
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At 12:42p -0400 on Sat, 26 Jul 2008, mos wrote:
> At 09:14 AM 7/26/2008, you wrote:
>> The reproducible part is very important, because without it, it's
>> suspect to be just your individual case, as with a bug in *your*
>> application code, your hardware, or generally something in your setup.
> Well, I thought it might be my code too. That's why when the memory
> table was built (without the index), I went to a SqlMgr and counted the
> rows. None of the rows were missing. Then I did an Alter Table and added
> one index to the memory table, and sure enough when it was finished 75%
> of the rows were missing and no error was reported. Only the rows for
> index values "A" to "E" were in the table so the indexing lost rows.

That suggests to me a couple of things, both bugs with MySQL:

- an out of memory error - MySQL should *not* fail, but tell you it
  can't complete and return you to a known state.  An RDBMS should
  *never* lose data.  Ever.

- a piece of data in one of the rows of processing that MySQL doesn't
  like, and therefore gives unexpected results.  This is definitely a
  bug as this should not happen to begin with, and "An RDBMS should
  *never* lose data.  Ever."

Summary: I don't know what's up and have not encountered this.  But if
you can, create a small test case that can reproduce the error.  Then
fill out a bug at .  Loss of data is absolutely a
bug, and a critical one.

A quick (< 3min) perusal of the bugs currently open did return any
meaningful results.

Adding index to Memory table LOSES ROWS!mos25 Jul
  • Re: Adding index to Memory table LOSES ROWS!Kevin Hunter26 Jul
    • Re: Adding index to Memory table LOSES ROWS!mos26 Jul
      • Re: Adding index to Memory table LOSES ROWS!Kevin Hunter27 Jul
        • Re: Adding index to Memory table LOSES ROWS!mos28 Jul