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Is concurrent query execution supported in monetdb?

While testing simultaneous query execution I found that only one query is getting executed at one time. Rest of the queries are put of hold until the first one gets completed. The test database has about 13 million records, I was trying to run the same query from three clients connected to the same monetdb server.

Example of the query:

select field1,field2,count(*) from def.testdata group by field1,field2

I am missing something here. Is there a multi user mode setting?

I am running this on 2 CPU 16GB host

Jawa
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jcarlson
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1 Answers1

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Parallel query execution is (of course) supported. However, there is currently a bug that might lead to sequential behavior, especially in your 2-CPU setting. See https://www.monetdb.org/bugzilla/show_bug.cgi?id=3665 . It has been already fixed, but not released yet. So you could checkout the Oct2014 branch from our source repository (hg clone http://dev.monetdb.org/hg/MonetDB/; cd MonetDB; hg update Oct2014) and compile it.

Hannes Mühleisen
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  • Thanks for the response. I will try it out. Also trying to install and verify this on 16 CPU box. – jcarlson Mar 22 '15 at 04:52
  • Not sure if it's the same case for me and I guess the issue you are talking about was released on MonetDB Database Server Toolkit v1.1 (Oct2014-SP4), but I'm getting really bad performance while running several concurrent queries. If I run my query it takes ~400ms, if i run the same query in 6 parallel threads each takes more than a second or two. Any idea why? – GBrian Aug 16 '15 at 20:24