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From Edmond Lau <edm...@ooyala.com>
Subject Would deleted columns slow down reads?
Date Fri, 26 Feb 2010 02:56:32 GMT
Given that Cassandra needs to maintain tombstones to handle
distributed deletes, does the existence of deleted columns slow down
slices?

To be more concrete, suppose I used a row as a queue.  I keep adding
columns to the end of the sort order of a column family, and I keep
deleting columns from the start of the sort order.  After some time,
the row would have a large number of deleted columns followed by a
number of undeleted columns in the column family.  Does slicing for
the first N columns from the row now require scanning over all the
initial deleted columns (meaning reads would get more expensive as
time goes on), or are the deleted columns stored separately to enable
Cassandra to skip over deleted columns when processing reads?

Edmond

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