I get roughly the same (~1.8s) - 100 rows, 200.000 columns, segment size 100
________________________________ From: Gurjeet Singh <[email protected]> To: [email protected]; lars hofhansl <[email protected]> Sent: Tuesday, August 21, 2012 11:31 AM Subject: Re: Slow full-table scans How does that compare with the newScanTable on your build ? Gurjeet On Tue, Aug 21, 2012 at 11:18 AM, lars hofhansl <[email protected]> wrote: > Hmm... So I tried in HBase (current trunk). > I created 100 rows with 200.000 columns each (using your oldMakeTable). The > creation took a bit, but scanning finished in 1.8s. (HBase in pseudo > distributed mode - with your oldScanTable). > > -- Lars > > > > ----- Original Message ----- > From: lars hofhansl <[email protected]> > To: "[email protected]" <[email protected]> > Cc: > Sent: Monday, August 20, 2012 7:50 PM > Subject: Re: Slow full-table scans > > Thanks Gurjeet, > > I'll (hopefully) have a look tomorrow. > > -- Lars > > > > ----- Original Message ----- > From: Gurjeet Singh <[email protected]> > To: [email protected]; lars hofhansl <[email protected]> > Cc: > Sent: Monday, August 20, 2012 7:42 PM > Subject: Re: Slow full-table scans > > Hi Lars, > > Here is a testcase: > > https://gist.github.com/3410948 > > Benchmarking code: > > https://gist.github.com/3410952 > > Try running it with numRows = 100, numCols = 200000, segmentSize = 1000 > > Gurjeet > > > On Thu, Aug 16, 2012 at 11:40 AM, Gurjeet Singh <[email protected]> wrote: >> Sure - I can create a minimal testcase and send it along. >> >> Gurjeet >> >> On Thu, Aug 16, 2012 at 11:36 AM, lars hofhansl <[email protected]> wrote: >>> That's interesting. >>> Could you share your old and new schema. I would like to track down the >>> performance problems you saw. >>> (If you had a demo program that populates your rows with 200.000 columns in >>> a way where you saw the performance issues, that'd be even better, but not >>> necessary). >>> >>> >>> -- Lars >>> >>> >>> >>> ________________________________ >>> From: Gurjeet Singh <[email protected]> >>> To: [email protected]; lars hofhansl <[email protected]> >>> Sent: Thursday, August 16, 2012 11:26 AM >>> Subject: Re: Slow full-table scans >>> >>> Sorry for the delay guys. >>> >>> Here are a few results: >>> >>> 1. Regions in the table = 11 >>> 2. The region servers don't appear to be very busy with the query ~5% >>> CPU (but with parallelization, they are all busy) >>> >>> Finally, I changed the format of my data, such that each cell in HBase >>> contains a chunk of a row instead of the single value it had. So, >>> stuffing each Hbase cell with 500 columns of a row, gave me a >>> performance boost of 1000x. It seems that the underlying issue was IO >>> overhead per byte of actual data stored. >>> >>> >>> On Wed, Aug 15, 2012 at 5:16 PM, lars hofhansl <[email protected]> wrote: >>>> Yeah... It looks OK. >>>> Maybe 2G of heap is a bit low when dealing with 200.000 column rows. >>>> >>>> >>>> If you can I'd like to know how busy your regionservers are during these >>>> operations. That would be an indication on whether the parallelization is >>>> good or not. >>>> >>>> -- Lars >>>> >>>> >>>> ----- Original Message ----- >>>> From: Stack <[email protected]> >>>> To: [email protected] >>>> Cc: >>>> Sent: Wednesday, August 15, 2012 3:13 PM >>>> Subject: Re: Slow full-table scans >>>> >>>> On Mon, Aug 13, 2012 at 6:10 PM, Gurjeet Singh <[email protected]> wrote: >>>>> I am beginning to think that this is a configuration issue on my >>>>> cluster. Do the following configuration files seem sane ? >>>>> >>>>> hbase-env.sh https://gist.github.com/3345338 >>>>> >>>> >>>> Nothing wrong w/ this (Remove the -ea, you don't want asserts in >>>> production, and the -XX:+CMSIncrementalMode flag if >= 2 cores). >>>> >>>> >>>>> hbase-site.xml https://gist.github.com/3345356 >>>>> >>>> >>>> This is all defaults effectively. I don't see any of the configs. >>>> recommended by the performance section of the reference guide and/or >>>> those suggested by the GBIF blog. >>>> >>>> You don't answer LarsH's query about where you see the 4% difference. >>>> >>>> How many regions in your table? Whats the HBase Master UI look like >>>> when this scan is running? >>>> St.Ack >>>>
