>From the HBase Shell: "hbase(main):003:0> major_compact
ERROR: Wrong # of arguments(0 for 1) Here is some help for this command: Run major compaction on passed table or pass a region row to major compact an individual region " So it looks like you can major_compact a region. Should be easy to open a table, get the start row of each region and then one by one do a major compaction. That would be less of a load on your system than doing a major compaction on the entire table all at once, right? HTH -Mike ---------------------------------------- > Date: Tue, 5 Apr 2011 13:45:44 +0300 > From: [email protected] > To: [email protected] > Subject: Compactions in busy system(s) > > Hi all, > > I'm not sure if I've understood well the purpose of major compaction and > how to handle it in a busy system. > It is important to run major compaction when we have a lot of deleted > data, as it removes the "marked as deleted" flags. > There are also the "flush" and "minor compaction" operations associated > with the writing on disk. I understand that in minor compaction many > files resulted from flush operations are written in only one file. What > is not very clear is whether major compaction does the same operation > (and so it can be skipped if no deletes are in the system) or there is > also a particular operation which is not done in minor compaction and > skipping it may affect the performance or volume. > > An other thing that I'd like you to help me clarifying is if major > compaction on all dataset is the sum of major compaction of all regions. > If so, it is possible to major compact only some regions at a time, and > other regions at other time. I also don't understand well if it is > possible for the system to merge a region with less data with other > region and if it does, which of the mentioned operations might affect > the good system behavior(i.e. what NOT to do). > > The last point is regarding the files in HDFS (this might affect the > volume). When is the data deleted from HDFS(in minor and major > compaction)? Are the files deleted when a compaction is performed or > they are only marked as deleted? > > Thank you, > Iulia > > > > -- > Iulia Zidaru > Java Developer > > 1&1 Internet AG - Bucharest/Romania - Web Components Romania > 18 Mircea Eliade St > Sect 1, Bucharest > RO Bucharest, 012015 > [email protected] > 0040 31 223 9153 > > >
