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From Ben West <bwsithspaw...@yahoo.com>
Subject Custom timestamps
Date Wed, 19 Oct 2011 19:18:38 GMT
Hi all,

We're storing timestamped data in HBase; from lurking on the mailing list it seems like the
recommendation is usually to make the timestamp part of the row key. I'm curious why this
is - is scanning over rows more efficient than scanning over timestamps within a cell? 

The book says: "the version timestamp is internally by HBase for things like time-to-live
calculations. It's usually best to avoid setting this timestamp yourself. Prefer using a separate
timestamp attribute of the row, or have the timestamp a part of the rowkey, or both." I understand
that TTL would be ruined (or saved, depending on your goal) by custom timestamps, and I also
gather that the way HBase handles concurrency is through MVCC. But we are using application
level locks, and HBase's TTL functionality applying is a bonus if anything.

So is there any reason why we shouldn't set the timestamps manually?

Thanks!
-Ben

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