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Re: Is Union Queries run in Parallel form or not.
Posted by: Øystein Grøvlen
Date: October 19, 2017 03:02AM

> I wan to ask that these queries run in parallel
> form or in order one by one ?

They will be run one by one. MySQL does only use one thread per connection.

> What can I do to increase the performance of this
> query. Can I create thread for each query ?

Only way to get one thread per query is to run each query in a separate connection. Note that this implies that the queries will run in different transactions, and possibly see a different set of concurrent updates.

> If I create three thread for this query with
> single connection is it work in parallel or not ?

Traditionally, a connection can only have one outstanding request at a time, so the queries can not be run in parallel if using the standard MySQL Protocol. However, you can get asynchronous execution by using the X Plugin for MySQL. See for an example.

> or I need to create three connection for each
> query to run parallel ?

Yes, unless you use the XPlugin.

Øystein Grøvlen,
Senior Principal Software Engineer,
MySQL Group, Oracle,
Trondheim, Norway

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Re: Is Union Queries run in Parallel form or not.
October 19, 2017 03:02AM

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