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A large portion of my queries (~58%) be it for queries with previously quick return rates or other, are spending in my monitor as sending data. I made some configuration changes but it was very broad and I failed to use version control.

Would it have to do with max packet size or the net_ variables being set too small? or perhaps a small max_join size? Many of our tables are unavoidably resulting in cartesian jobs until we can go NoSQL.


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The sending data state is deceptively-named. It does not necessarily mean that data is being sent. Long-running queries spend much of their time in this state. The most likely explanation does not involve configuration variables -- it most likely indicates problems with your query design or stale index statistics that are sending the optimizer down the wrong path. Posting the output of EXPLAIN SELECT from one of your slow queries might be of value here. –  Michael - sqlbot Jan 23 '13 at 22:47
@Michael-sqlbot thanks for this I find I also have a number that will get stuck in in Removing Duplicates - the database we work with is of Government origin, so go figure it is probably the worst indexed and unwieldy thing imaginable. We've done a lot where we can but Cartesian join doesn't even do justice to some of the things we run. I will post an EXPLAIN. Thanks! –  cerd Feb 27 '13 at 6:57

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