Do you see the same slowdown with the default 64k block size? Lars <[email protected]> schrieb:
>I'll be busy today... I'll double check my scanning related changes as soon as >i can. > >Jean-Daniel Cryans <[email protected]> schrieb: > >>Yes and yes. >> >>J-D >>On Dec 14, 2011 5:52 PM, "Matt Corgan" <[email protected]> wrote: >> >>> Regions are major compacted and have empty memstores, so no merging of >>> stores when reading? >>> >>> >>> 2011/12/14 Jean-Daniel Cryans <[email protected]> >>> >>> > Yes sorry 1.1M >>> > >>> > This is PE, the table is set to a block size of 4KB and block caching >>> > is disabled. Nothing else special in there. >>> > >>> > J-D >>> > >>> > 2011/12/14 <[email protected]>: >>> > > Thanks for the info, J-D. >>> > > >>> > > I guess the 1.1 below is in millions. >>> > > >>> > > Can you tell us more about your tables - bloom filters, etc ? >>> > > >>> > > >>> > > >>> > > 在 Dec 14, 2011，5:26 PM，Jean-Daniel Cryans <[email protected]> 写道： >>> > > >>> > >> Hey guys, >>> > >> >>> > >> I was doing some comparisons between 0.90.5 and 0.92.0, mainly >>> > >> regarding reads. The numbers are kinda irrelevant but the differences >>> > >> are. BTW this is on CDH3u3 with random reads. >>> > >> >>> > >> In 0.90.0, scanning 50M rows that are in the OS cache I go up to about >>> > >> 1.7M rows scanned per second. >>> > >> >>> > >> In 0.92.0, scanning those same rows (meaning that I didn't run >>> > >> compactions after migrating so it's picking the same data from the OS >>> > >> cache), I scan about 1.1 rows per second. >>> > >> >>> > >> 0.92 is 50% slower when scanning. >>> > >> >>> > >> In 0.90.0 random reading 50M rows that are OS cached I can do about >>> > >> 200k reads per second. >>> > >> >>> > >> In 0.92.0, again with those same rows, I can go up to 260k per second. >>> > >> >>> > >> 0.92 is 30% faster when random reading. >>> > >> >>> > >> I've been playing with that data set for a while and the numbers in >>> > >> 0.92.0 when using HFileV1 or V2 are pretty much the same meaning that >>> > >> something else changed or the code that's generic to both did. >>> > >> >>> > >> >>> > >> I'd like to be able to associate those differences to code changes in >>> > >> order to understand what's going on. I would really appreciate if >>> > >> others also took some time to test it out or to think about what could >>> > >> cause this. >>> > >> >>> > >> Thx, >>> > >> >>> > >> J-D >>> > >>>
