Hi, So it was the case that the region sizes were very skewed, partly due to the IncreasingToUpperBoundRegionSplitPolicy, which favours making lots of smaller regions early on.
I couldn't find a tool to show regions and their sizes, for a specific table, so ended up writing one. I used that output to issue merge_online requests to the shell tool for each adjacent region pair, where the sum of the sizes was less than some setting (which I estimated to be the (total table size) / (# of desired regions). Ran the tool a few times and managed to get 443 regions -> 48, with much less size skew between the regions. A very rough algorithm (it doesn't split regions larger than the desired size) but hopefully useful to others. Thanks for the help! - Nasron On Fri, Jun 19, 2015 at 3:47 AM, Dejan Menges <dejan.men...@gmail.com> wrote: > Just have to say that hbase.master.loadbalance.bytable saved us after we > discovered it. In our case we had to set it manually to true, and then it > was easy to catch hot spotting on unusually large regions and handle it. > > Btw +1 for HBASE-13013, had to say it, something that makes me starting > upgrading our HDP stack on Monday morning. > > On Thu, Jun 18, 2015 at 11:04 PM, Bryan Beaudreault < > bbeaudrea...@hubspot.com> wrote: > > > Just had to say, https://issues.apache.org/jira/browse/HBASE-13103 looks > > *AWESOME* > > > > On Thu, Jun 18, 2015 at 5:00 PM Mikhail Antonov <olorinb...@gmail.com> > > wrote: > > > > > Yeah, I could see 2 reasons for remaining few regions to take > > > unproportionally long time - 1) those regions are unproportionally > > > large (you should be able to quickly confirm it) and 2) they happened > > > to be hosted on really slow/overloaded machine(s). #1 seems far more > > > likely to me. > > > > > > And as Nick said, there's ongoing effort to provide exactly what > > > you've described - centralized periodic analysis of region sizes and > > > equalization as needed (somewhat complementary to balancing), and any > > > feedback (especially from folks experiencing real issues with unequal > > > region sizes) is much appreciated. > > > > > > -Mikhail > > > > > > On Thu, Jun 18, 2015 at 10:07 AM, Nick Dimiduk <ndimi...@gmail.com> > > wrote: > > > > If you're interested in region size balancing, please have a look at > > > > https://issues.apache.org/jira/browse/HBASE-13103 . Please provide > > > feedback > > > > as we're hoping to have an early version available in 1.2. > > > > > > > > Which reminds me, I owe Mikhail another review... > > > > > > > > On Thu, Jun 18, 2015 at 9:39 AM, Elliott Clark <ecl...@apache.org> > > > wrote: > > > > > > > >> The balancer is not responsible fore region size decisions. The > > > balancer is > > > >> only responsible for deciding which regionservers should host which > > > >> regions. > > > >> Splits are determined by data size of a region. See max store file > > size. > > > >> > > > >> On Thu, Jun 18, 2015 at 7:50 AM, Nasron Cheong <nas...@gmail.com> > > > wrote: > > > >> > > > >> > Hi, > > > >> > > > > >> > I've noticed there are two settings available when using the HBase > > > >> balancer > > > >> > (specifically the default stochastic balancer) > > > >> > > > > >> > hbase.master.balancer.stochastic.tableSkewCost > > > >> > > > > >> > hbase.master.loadbalance.bytable > > > >> > > > > >> > How do these two settings relate? The documentation indicates when > > > using > > > >> > the stochastic balancer that 'bytable' should be set to false? > > > >> > > > > >> > Our deployment relies on very few, very large tables, and I've > > noticed > > > >> bad > > > >> > distribution when accessing some of the tables. E.g. there are 443 > > > >> regions > > > >> > for a single table, but when doing a MR job over a full scan of > the > > > >> table, > > > >> > the first 426 regions scan quickly (minutes), but the remaining 17 > > > >> regions > > > >> > take significantly longer (hours) > > > >> > > > > >> > My expectation is to have the balancer equalize the size of the > > > regions > > > >> for > > > >> > each table. > > > >> > > > > >> > Thanks! > > > >> > > > > >> > - Nasron > > > >> > > > > >> > > > > > > > > > > > > -- > > > Thanks, > > > Michael Antonov > > > > > >
