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From Shawn Heisey <apa...@elyograg.org>
Subject Re: MatchAllDocsQuery is much slower in solr5.3.1 compare to solr4.7
Date Fri, 06 Nov 2015 21:41:07 GMT
On 11/6/2015 1:01 PM, wei wrote:
> Thanks Jack and Shawn. I checked these Jira tickets, but I am not sure if
> the slowness of MatchAllDocsQuery is also caused by the removal of
> fieldcache. Can someone please explain a little bit?

I only glanced at your full output in the message at the start of this
thread.  I thought I saw facet output in it, but it turns out that the
only mention of facets was the timing information from the debug, so
that very likely rules out the FieldCache change as a culprit.

I am suspecting that the 4.7 index is warmed better, and may have the
specific filter query (categoryIdsPath:1001)already sitting in the
filterCache.

Try running that query a few of times on both versions, then restart
Solr on both versions so they both start clean, and run the query *once*
on each system, and see whether there's still a large discrepancy.

If one of the systems is receiving queries from active clients and the
other is not, then the comparison will be unfair, and biased towards the
one that is getting additional queries.  Query activity, even if it
seems unrelated to the query you are testing, has a tendency to reduce
overall qtime values.

Thanks,
Shawn


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