All right, I understand the integrity cost is there because we don't get transactions in HBase over multiple tables. Thanks a lot for your time and help :)
Hari On Mon, Feb 21, 2011 at 11:09 AM, Ted Yu <[email protected]> wrote: > 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 > > > > > > > > > >
