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Re: "Sending Data" is taking time post migration from 5.1 to 5.6
Posted by: Peter Brawley
Date: March 14, 2017 09:42AM

Ah, you neglected to mention that the Update has a Join!

update bct_va_res1_tmp a
join bct_prod b on a.head_prodno=b.prodno and a.head_rstate=b.rstate
set a.description=b.description
where a.level=0 ;

MySQL can't find an index for b so it's having to examine 113*556464=62,880,432 rows; bct_prod needs index(prodno,rstate).

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