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From Peter Schuller <peter.schul...@infidyne.com>
Subject Re: Atomically adding a column to columns_
Date Mon, 27 Sep 2010 20:54:29 GMT
> Function addColumn at class SuperColumn tries to atomically add a column to
> the concurrent collection “columns_” using the following code:

Deletions in Cassandra involve an insertion of a tombstone rather than
actual column deletion.

In the case of this bit of code, I believe, and I am not speaking
authoritatively, the removal only happens in (1) the read path when
filtering results (on presumably query-local data) and (2) during
compaction (on presumably compaction-local data). I did browse through
the various callers which seemed to confirm that this was the case. In
other words, I do not believe the remove() code path should not ever
be taken concurrently with insertions (by design, and not by
accident).

Anyone care to confirm/deny?

-- 
/ Peter Schuller

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