One particular region is for only one table. So the answer to your first question is no.
For your use case, you need to consider the cost of maintaining 4 index tables (in terms of data integrity). You should try to minimize the number of index tables. On Sun, Feb 20, 2011 at 7:50 PM, Hari Sreekumar <[email protected]>wrote: > So if I have 10 tables each with 2 families, I'd open up 20 stores whenever > I open a region for reading? Is it a problem to have too many tables. e.g, > if I have 1 big table and 4 indexing tables for the big table? Are there > any > potential issues with this? > > Thanks, > Hari > > On Sun, Feb 20, 2011 at 8:47 PM, Ted Yu <[email protected]> wrote: > > > >> Does this mean that a store instance is opened for all tables present > in > > >> HBase irrespective of which table we are querying and for all > > >> columnfamilies? > > No. The blog says Store instance is for each family. > > > > You should generally avoid multiple column families. But we can help you > > analyze your use case. > > If you read through https://issues.apache.org/jira/browse/HBASE-3149, > you > > would better understand current implementation. > > > > On Sun, Feb 20, 2011 at 6:38 AM, Hari Sreekumar < > [email protected] > > >wrote: > > > > > Hi, > > > > > > I was going through the HBase architecture blog by Lars George ( > > > http://www.larsgeorge.com/2009/10/hbase-architecture-101-storage.html) > > and > > > I just wanted a clarification regarding how HBase reads data. The blog > > > mentions that : > > > > > > Next the HRegionServer opens the region it creates a corresponding > > > HRegion object. > > > When the HRegion is "opened" it sets up a Store instance for each > > > HColumnFamily for every table as defined by the user beforehand. Each > of > > > the Store instances can in turn have one or more StoreFile instances, > > which > > > are lightweight wrappers around the actual storage file called HFile. A > > > HRegion also has a MemStore and a HLog instance. We will now have a > look > > at > > > how they work together but also where there are exceptions to the rule. > > > > > > Does this mean that a store instance is opened for all tables present > in > > > HBase irrespective of which table we are querying and for all > > > columnfamilies? Is this why I generally see people avoiding large > number > > of > > > tables/large number of column families. If not, what is the reason for > > > that? > > > Is it true at all that we should avoid too many tables/CFs ? > > > > > > Thanks, > > > Hari > > > > > >
