I've filed https://issues.apache.org/jira/browse/HBASE-18090 some time ago and attached draft patch to it. It's not complete as we need some deeper changes in the way we open regions (see comments) but basic stuff works (I ended up going the other route and didn't have bandwidth to finish that - would be great if someone picked it up)
Mikhail On Mon, Sep 4, 2017 at 11:13 AM Chia-Ping Tsai <[email protected]> wrote: > That sounds good. There are some related issue. see > https://issues.apache.org/jira/browse/HBASE-4914 and > https://issues.apache.org/jira/browse/HBASE-4063. > > On 2017-09-04 15:06, libis <[email protected]> wrote: > > Hi > > > > When TableInputFormat is used to source an HBase table in a MapReduce > job, > > its splitter will make a map task for each region of the table. However, > in > > some cases, the user’s scan range may locate in a single region, > resulting > > in there is a only mapper. For example, the rowkey of the table is > > ‘md5(userid) + timestamp’, once client want to scan the data of a > specified > > user in the latest month with MR, it’s much possible that there is only > one > > mapper working. > > > > In order to scan data in parallel if the user's scan range located in a > > single region, should we split the scan range into serveral segments > within > > a region? > > > > Best, > > > > xinxin > > > -- Thanks, Michael Antonov
