Since Doug maintains HBA actively, you can trust what it says. For item 3, most of your observations are correct except for b): There is only one RegionServer hosting .META. table at a given time
On Fri, Jul 1, 2011 at 7:09 AM, Florin P <[email protected]> wrote: > Hello! > I've read the HBase architecture from the book > http://hbase.apache.org/book.html#architecture (HBA) > and confronted with HBase definitive guide (HBDG) > http://ofps.oreilly.com/titles/9781449396107/architecture.html > Some questions raised: > 1. How many MemStores can have Region? > HBDG: "A HRegion also has a MemStore" > HBA: "A Store hosts a MemStore". A Store corresponds to a column family > for a table for a given region. > 2. How many HLog instances are created per Region Servers? > HBDG:"A HRegion also has [...] a HLog instance" > HBA: "[...]and there is one HLog instance per RegionServer. " > 3. After reading the HBA, I've concluded (please correct me if I'm wrong), > that the are these reletionships > a) A RegionServer has one HLog instance > b) A RegionServer has one .META. table that holds meta information about > many HTable > c) A HTable can be split in many Regions. > d) A HTable can have many column family > e) A Column family has one Store > f) A Store can have zero ore more HFile instances > g) A Store can one MemStore > h) A column family can have zero or many columns > I'll look forward for your opinions and answers...and please complete with > your knowledge. > Thank you. > Regards, > Florin > >
