On Mon, Aug 19, 2013 at 11:52 PM, Monish r <[email protected]> wrote:
> Hi Jean, > s/Jean/Jean-Daniel ;) > Thanks for the explanation. > > Just a clarification on the third answer, > > In our current cluster ( 0.90.6 ) , i find that irrespective of whether TTL > is set or not , Major compaction compaction rewrites hfile for the region ( > there is only one hfile for that region ) on every manual major compaction > trigger. > Can you enable DEBUG logs? You'd see why the major compaction is triggered. > > log : > > 2013-08-19 14:15:29,926 INFO org.apache.hadoop.hbase.regionserver.Store: > Completed major compaction of 1 file(s), new > > file=hdfs://x.x.x.x:9000/hbase/NOTIFICATION_HISTORY/b00086bca62ee55796a960002291aca4/n/4754838096619480671 > > i find a new file is created for every major compaction triggger. > > Regards, > R.Monish > > > On Mon, Aug 19, 2013 at 11:52 PM, Jean-Daniel Cryans <[email protected] > >wrote: > > > Inline. > > > > J-D > > > > > > On Mon, Aug 19, 2013 at 2:48 AM, Monish r <[email protected]> wrote: > > > > > Hi guys, > > > I have the following questions in HBASE 0.90.6 > > > > > > 1. Does hbase use only one compaction thread to handle both major and > > minor > > > compaction? > > > > > > > Yes, look at CompactSplitThread > > > > > > > > > > 2. If hbase uses multiple compaction threads, which configuration > > parameter > > > defines the number of compaction threads? > > > > > > > It doesn't in 0.90.6 but CompactSplitThread lists those for 0.92+ > > > > hbase.regionserver.thread.compaction.large > > hbase.regionserver.thread.compaction.small > > > > > > > > > > 3. After hbase.majorcompaction.interval from last major compaction ,if > > > major compaction is executed on a table already major compacted Does > > hbase > > > skip all the table regions from major compaction? > > > > > > > Determining if something is major-compacted is definitely not at the > > table-level. > > > > In 0.90.6, MajorCompactionChecker will ask HRegion.isMajorCompaction() to > > check if it needs to major compact again, which in turns checks every > > Store. FWW if you have TTL turned on it will still major compact a major > > compacted file, HFiles don't have an index of what's deleted or TTL'd and > > it doesn't do a full read of each files to check. > > > > > > > > > > Regards, > > > R.Monish > > > > > >
