Nishant Khurana wrote:
Hi,
I was looking at the API Docs and HQL shell to create tables for Hbase. I
couldn't figure out :
1) How to create column families such that each column family contains more
than one column through shell.
Please tell us how you tripped over HQL. It was remove from hbase quite
a while ago. We need to fix our documentation links if folks are
continuing to trip over it.
HBase shell is documented here, off the main wiki page for hbase:
http://wiki.apache.org/hadoop/Hbase/Shell.
To answer your question, there is nothing special to do adding new
columns; just create the column family and then add columns. As long as
the columns carry an existing column family prefix, hbase won't complain.
To create a table 'x', with a column family 'x', do this in the shell:
create 'x', 'x'
Type 'help' in the shell for more info.
2) Also if I want to do it programmatically, HColumnDescriptor class only
lets you create column families with single columns. Is there a way to do it
?
See above. Yes, you only create the column family when defining your
schema. Thereafter you can add columns without modifying schema.
Also If I am not wrong, we can store multiple values of each column in each
column family ?
Yes.
Is there a way I can do a bulk import from a structured text file into Hbase
through the shell or any script already available
Usually folks write mapreduce jobs to load up hbase. If you want to
write a script to load hbase, see the aforementioned shell link. Has
some notes on how you to script the shell or on how to write a script in
jruby. Otherwise, there are python/jython examples here:
http://wiki.apache.org/hadoop/Hbase/Shell
St.Ack
