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
RegionServers).
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?
