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From Josh Elser <>
Subject Re: Performance degradation on query analysis
Date Tue, 17 Sep 2019 14:15:43 GMT
Can you share the output you see from the EXPLAIN? Does it differ 
between times it's "fast" and times it's "slow"?

Sharing the table(s) DDL statements would also help, along with the 
shape and version of your cluster (e.g. Apache Phoenix 4.14.2 with 8 

Spit-balling ideas:

Could be reads over the SYSTEM.CATALOG table or the SYSTEM.STATS table.

Have you looked more coarsely at the RegionServer logs/metrics? Any 
obvious saturation issues (e.g. handlers consumed, JVM GC pauses, host 
CPU saturation)?

Turn on DEBUG log4j client side (beware of chatty ZK logging) and see if 
there's something obvious from when the EXPLAIN is slow.

On 9/17/19 3:58 AM, Stepan Migunov wrote:
> Hi
> We have an issue with our production environment - from time to time we notice a significant
performance degradation for some queries. The strange thing is that the EXPLAIN operator for
these queries takes the same time as queries execution (5 minutes or more). So, I guess, the
issue is related to query's analysis but not data extraction. Is it possible that issue is
related to SYSTEM.STATS access problem? Any other ideas?

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