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From:mos Date:January 12 2009 7:54pm
Subject:Re: Why does changing a table property rebuild the table?
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At 12:14 PM 1/12/2009, Dan Nelson wrote:
>In the last episode (Jan 12), mos said:
> > I'm using MySQL 5.1 and if I execute:
> >
> > alter table mytable delay_key_write=1;
> >
> > it takes about an hour to rebuild the table. Why? As far as I know it
> > is not changing the table structure. So why does it have to make a
> > copy of the table and reload all the data?
>
>Mysql plays it safe and assumes that any table modification requires a
>full rebuild.  5.1 knows that certain settings don't require a full
>rebuild, but delay_key_writes isn't one of them (and some that are
>marked as fast shouldn't be - see
>http://bugs.mysql.com/bug.php?id=39372 ).

Dan,
       Why would delay_key_writes require a table rebuild? It's not 
modifying the data. Reloading tens of millions of rows for several hours 
seems to be a waste of time.

Mike 

Thread
Why does changing a table property rebuild the table?mos12 Jan
  • Re: Why does changing a table property rebuild the table?Dan Nelson12 Jan
    • Re: Why does changing a table property rebuild the table?mos12 Jan
      • Re: Why does changing a table property rebuild the table?Dan Nelson12 Jan
        • Re: Why does changing a table property rebuild the table?Baron Schwartz13 Jan
          • Re: Why does changing a table property rebuild the table?mos14 Jan