No, you can't assure the same data will be addressed without at least including an order
by. Even then you would need to make sure
that the first X records in the order would not change. For instance, if you order by
entered_date DESC, then the data set would
change because any new records would get included in the LIMIT.
----- Original Message -----
From: "Ian P. Christian" <pookey@stripped>
To: <mysql@stripped>
Sent: Friday, March 30, 2007 8:18 AM
Subject: a 'safe' way to move data?
> I'm trying to move data between 2 tables.
>
> > INSERT INTO new_table SELECT * FROM old_table LIMIT 50000;
> > DELETE FROM old_table LIMIT 50000;
>
> This is the only process that deletes data from old_table, can I be *sure* that the
> limit in these 2 queries will address the same
> data set?
>
> (if I don't limit to small numbers in the LIMIT, I/O gets too high, so I'm moving
> data slowly in batches)
>
> Thanks,
>
> --
> Ian P. Christian ~ http://pookey.co.uk
>
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