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Re: Fast Update
Posted by: Peter Brawley
Date: November 30, 2016 08:17PM

What MySQL version are you running?

In( select... ) semi-joins are slower than joins, increasingly slower the earlier the version.

And, whether it's a semijoin or a join, it needs index(lname,fname,mname,address,city,state,zip) to perform.

Once that index is in place, I'd want to compare the performance of your query with that of a conventional exclusion join ...

update exclusive a
left join exclusive_temp b using(lname,fname,mname,address,city,state,zip)
set a.deleted_date=now()
where a.deleted_date is null and b.lname is null;

5.7 may run that query faster than pre-5.7 versions.

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