Please disregard. James may have nailed it and that's not version dependent.
On Tuesday, March 5, 2013, Andrew Purtell wrote: > Do you have timing results for an Apache HBase release? Our last release > was 0.94.5. > > On Tuesday, March 5, 2013, Kim Hamilton wrote: > >> Hi all, >> I've been lurking here for a while, so thanks for all the valuable tips >> and >> guidance you've given so far. >> >> I'm running some experiments to understand where to use coprocessors. One >> interesting scenario is computing distinct values. I ran performance tests >> with two distinct value implementations: one using endpoint coprocessors, >> and one using just scans (computing distinct values client side only). I >> noticed that the endpoint coprocessor implementation averaged 80 ms slower >> than the scan implementation. Details of that are below for anyone >> interested. >> >> To drill into the performance, I instrumented the code and ultimately >> deployed a no-op endpoint coprocessor, to look at the overhead of simply >> calling it. I'm measuring around 100ms for calling my empty, no-op >> endpoint >> coprocessor. >> >> I need to do more tests, but I believe my tests are leading me to similar >> conclusions drawn here: >> http://hbase-coprocessor-experiments.blogspot.com/2011/05/extending.html >> >> I.e. if the query/scan is selective enough (I'll go out on a limb and >> estimate 50-100 rows), then it's better to just perform a scan and compute >> client side. Endpoint coprocessors will make sense for larger result sets >> and/or scans that hit multiple regions. >> >> Before going too far, I wanted to check if anyone in this group has >> suggestions. I.e. perhaps there are just some configuration options I've >> not uncovered. Does this 100ms latency sound correct? >> >> Thanks, >> Kim >> >> >> *Detailed results of distinct value comparison, just FYI* >> >> Using 0.92.1-cdh4.1.0 >> Scan result size ~50-100 >> Row size 1kb, but after filtering for only desired columns, 380 bytes >> >> *with coprocessors* >> AverageLatency(ms), 176.1353 >> MinLatency(ms), 42 >> MaxLatency(ms), 2368 >> 95thPercentileLatency(ms), 321 >> 99thPercentileLatency(ms), 422 >> >> *scan-only, compute distinct values client side* >> AverageLatency(ms), 92.8165 >> MinLatency(ms), 4 >> MaxLatency(ms), 986 >> 95thPercentileLatency(ms), 253 >> 99thPercentileLatency(ms), 356 >> > > > -- > Best regards, > > - Andy > > Problems worthy of attack prove their worth by hitting back. - Piet Hein > (via Tom White) > > -- Best regards, - Andy Problems worthy of attack prove their worth by hitting back. - Piet Hein (via Tom White)
