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From Stack <st...@duboce.net>
Subject Re: Is there a API to get all the columns of a column family
Date Tue, 14 Feb 2012 04:15:59 GMT
On Mon, Feb 13, 2012 at 6:00 PM, hongqizh <hqzhang@talend.com> wrote:
> Thanks for your quick response. In my case, the tables comes from customers
> so I can't modify those tables, and some of the tables are very large(for
> example, one is more than 600MB) , when I scanning all the data of the
> table, the program just does not respond.

Why not?  It stops at a particular region?  Can you figure which one.
Is it not deployed anywhere?   Grep its name in master logs to see if
you can figure what happened to it?

>  Do you have a suggestion about
> this kind of case? And I think more and more people will encounter this
> problem,  is that possible in future to add the API to get all the column
> names of a column family(such as HColumnDescriptor.getColumnNames() )?
>

I don't think we'll be adding such a call; it would imply a full scan
of the whole table to find every unique column of which there could be
millions.  If the table is big, it'd need to mapreduce for the result
to come back in any reasonable amount of time.

St.Ack

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