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From Josh Elser <>
Subject Re: Column Scan / table metadata
Date Wed, 18 Sep 2013 18:57:28 GMT
There isn't a reliable way to ascertain the column set for a table via the
Accumulo API.

Scanning all of the keys in a table would work; however, this quickly
becomes too costly to perform for modestly sized tables.

An easy way to manage this is to build up the set of columns as part of
your "ingest" code and store them in Accumulo (a separate table is
easiest). By adding a quick cache to your ingest code, you can track a
column schema without much extra effort or cost.

On Wed, Sep 18, 2013 at 2:42 PM, Devin Pinkston <>wrote:

> I have been looking through the Accumulo source to try and find the best
> way to derive the column structure/metadata of a table.  If I have a table
> "sample", and I want to find all the column families/qualifiers, is there a
> built-in facility in Accumulo to get a list of columns in that table?  Or
> would my best option be to scan() the entire table, and only put unique
> column families/qualifiers into a list and return to the user?
> I am imagining the user has no idea of what their columns are like in this
> table, that is why I ask.
> Thanks!

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