In case of HBase normal scan as we know, regions will be scanned sequentially. Pheonix having parallel scan impls in it. When RLI is used and we make use of index completely at server side, it is irrespective of client scan ways. Sequential or parallel, using java or any other client layer or using SQL layer like Phoenix, using MR or not... all client side dont have to worry abt this but the usage will be fully at server end.
Yes when parallel scan is done on regions, RLI might perform much better. -Anoop- On Fri, Jan 3, 2014 at 7:35 PM, rajeshbabu chintaguntla < rajeshbabu.chintagun...@huawei.com> wrote: > No. the regions scanned sequentially. > ________________________________________ > From: Asaf Mesika [asaf.mes...@gmail.com] > Sent: Friday, January 03, 2014 7:26 PM > To: user@hbase.apache.org > Subject: Re: secondary index feature > > Are the regions scanned in parallel? > > On Friday, January 3, 2014, rajeshbabu chintaguntla wrote: > > > > > Here are some performance numbers with RLI. > > > > No Region servers : 4 > > Data per region : 2 GB > > > > Regions/RS| Total regions| Blocksize(kb) |No#rows matching values| Time > > taken(sec)| > > 50 | 200| 64|199|102 > > 50 | 200|8|199| 35 > > 100|400 | 8| 350| 95 > > 200| 800| 8| 353| 153 > > > > Without secondary index scan is taking in hours. > > > > > > Thanks, > > Rajeshbabu > > ________________________________________ > > From: Anoop John [anoop.hb...@gmail.com <javascript:;>] > > Sent: Friday, January 03, 2014 3:22 PM > > To: user@hbase.apache.org <javascript:;> > > Subject: Re: secondary index feature > > > > >Is there any data on how RLI (or in particular Phoenix) query throughput > > correlates with the number of region servers assuming homogeneously > > distributed data? > > > > Phoenix is yet to add RLI. Now it is having global indexing only. Correct > > James? > > > > RLI impl from Huawei (HIndex) is having some numbers wrt regions.. But I > > doubt whether it is there large no# RSs. Do you have some data Rajesh > > Babu? > > > > -Anoop- > > > > On Fri, Jan 3, 2014 at 3:11 PM, Henning Blohm <henning.bl...@zfabrik.de > > >wrote: > > > > > Jesse, James, Lars, > > > > > > after looking around a bit and in particular looking into Phoenix > (which > > I > > > find very interesting), assuming that you want a secondary indexing on > > > HBASE without adding other infrastructure, there seems to be not a lot > of > > > choice really: Either go with a region-level (and co-processor based) > > > indexing feature (Phoenix, Huawei, is IHBase dead?) or add an index > table > > > to store (index value, entity key) pairs. > > > > > > The main concern I have with region-level indexing (RLI) is that Gets > > > potentially require to visit all regions. Compared to global index > tables > > > this seems to flatten the read-scalability curve of the cluster. In our > > > case, we have a large data set (hence HBASE) that will be queried > (mostly > > > point-gets via an index) in some linear correlation with its size. > > > > > > Is there any data on how RLI (or in particular Phoenix) query > throughput > > > correlates with the number of region servers assuming homogeneously > > > distributed data? > > > > > > Thanks, > > > Henning > > > > > > > > > > > > > > > On 24.12.2013 12:18, Henning Blohm wrote: > > > > > >> All that sounds very promising. I will give it a try and let you know > > >> how things worked out. > > >> > > >> Thanks, > > >> Henning > > >> > > >> On 12/23/2013 08:10 PM, Jesse Yates wrote: > > >> > > >>> The work that James is referencing grew out of the discussions Lars > > >>> and I > > >>> had (which lead to those blog posts). The solution we implement is > > >>> designed > > >>> to be generic, as James mentioned above, but was written with all the > > >>> hooks > > >>> necessary for Phoenix to do some really fast updates (or skipping > > updates > > >>> in the case where there is no change). > > >>> > > >>> You should be able to plug in your own simple index builder (there is > > >>> an example > > >>> in the phoenix codebase<https://github.com/forcedotcom/phoenix/tree/ > > >>> master/src/main/java/com/salesforce/hbase/index/covered/example>) > > >>> to basic solution which supports the same transactional guarantees as > > >>> HBase > > >>> (per row) + data guarantees across the index rows. There are more > > details > > >>> in the presentations James linked. > > >>> > > >>> I'd love you see if your implementation can fit into the framework we > > >>> wrote > > >>> - we would be happy to work to see if it needs some more hooks or > > >>> modifications - I have a feeling this is pretty much what you guys > will > > >>> need > > >>> > > >>> -Jesse > > >>> > > >>> > > >>> On Mon, Dec 23, 2013 at 10:01 AM, James Taylor< > jtay...@salesforce.com> > > >>> wrote: > > >>> > > >>> Henning, > > >>>> Jesse Yates wrote the back-end of our global secondary indexing > system > > >>>> in > > >>>> Phoenix. He designed it as a separate, pluggable module with no > > Phoenix > > >>>> dependencies. Here's an overview of the feature: > > >>>> https://github.com/forcedotcom/phoenix/wiki/Secondary-Indexing. The > > >>>> section that discusses the data guarantees and failure management > > might > > >>>> be > > >>>> of interest to you: > > >>>> > https://github.com/forcedotcom/phoenix/wiki/Secondary-Indexing#data- > > >>>> guarantees-and-failure-management > > >>>> > > >>>> This presentation also gives a good overview of the pluggability of > > his > > >
