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From Lam <>
Subject querying for relevant rows
Date Fri, 29 Jun 2012 18:19:19 GMT
I'm using a timestamp as a key and the value is all the relevant data
starting at that timestamp up to the timestamp represented by the key
of the next row.

When querying, I'm given a time span, consisting of a start and stop
time.  I want to return all the relevant data within the time span, so
I was to retrieve the appropriate rows (then filter the data for the
given timespan).

In Accumulo:  (the format of the value is  <letter>.<timestamp>)
    key=1  value= {a.1 b.1 c.2 d.2}
    key=3  value= {m.3 n.4 o.5}
    key=6  value={x.6 y.6 z.7}

Query:  timespan=[2 4]  (get all data from timestamp 2 to 4 inclusively)

Desire result: retrieve key=1 and key=3, then filter out a.1, b.1, and
o.5, and return the rest

Problem: How do I know to retrieve key=1 and key=3 without scanning
all the keys?

Can I create a scanner that looks for the given start key=2 and go to
the prior row (i.e. key=1)?

D. Lam

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