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From Randy Hu <ruw...@gmail.com>
Subject Re: phoenix query modtime
Date Fri, 23 Jun 2017 22:50:31 GMT
First HBase does not have a concept of "row timestamp". Timestamp is part
of each cell. The closest to row timestamp is probably the latest timestamp
from all cells with same row key.

The reason that timestamp column need to be part of primary key is that
there could be multiple values with different timestamps but same row key,
family. and qualifier. The SQL result data model does not support such two
dimension structure well. The best Phoenix can do in the SQL model is to
return list of values in array, but then the cell timestamp need to be
returned in another array with same length under different column name. You
can imagine the mess and awkwardness it could be if going to that
direction. It's much straightforward to make time stamp part of primary
key, so the two dimension structure could be represented by multiple rows
naturally in SQL result.

Randy




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