Can you post the query and data set?  In general, the static / fast query optimizer does a very good job.  However, there are always queries that it can get wrong.  That's why we provide two other query optimizers.  

Query optimization for databases is a never ending process.  

Bryan

From: feugen24 <feugen24@users.sf.net>
Reply-To: "[bigdata:discussion]" <676946@discussion.bigdata.p.re.sf.net>
Date: Tuesday, March 18, 2014 9:48 AM
To: "[bigdata:discussion]" <676946@discussion.bigdata.p.re.sf.net>
Subject: [bigdata:discussion] Bigdata query optimizer

Hi,
While testing various scenarios I loaded db with ~7M triples and I noticed the default static optimizer fails in simple scenarios, meaning that it rearranges the query so it joins much more than needed.
For example given a inner query that binds a ?s variable to 3 values, if i want to get all triples for ?s (~ 10 triples) and I join with ?s ?p ?o, it takes few minutes to get them (and 2G of ram), but with optimizer set to "None" or "Runtime" it's just few ms as it should.

If someone is evaluating the db he will get the impression of poor performance. Also I tried to find a config setting that changes the default optimizer since now I have to set it to None in all queries.
So can I set a default?
In general the performance should be better with static optimizer so i should try to use it?
In this kind of situations a bug should be reported? (I have the impression the query is v simple so it should work fine with any optimizer)

Thanks


Bigdata query optimizer


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