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From Mark Robson <mar...@gmail.com>
Subject Re: why does remove need a timestamp?
Date Mon, 09 Nov 2009 10:43:27 GMT
2009/11/9 Ramzi Rabah <rrabah@playdom.com>

> Hello all:
> I am confused about the need of passing a  timestamp for the remove
> operation. Why does the remove operation in Cassandra require a
> timestamp? What happens if I provide a remove call with a different
> timestamp than what I inserted, will the row still be deleted?
>

It is so that if the commands are replayed in a different order on different
nodes, the same result is produced.

Remove only removes values which have a timestamp of before or the same as
the one provided - this is essential, as if a "later" insert "overtakes" the
remove, the remove needs to avoid removing "newer" data.

The eventual consistency model only works (i.e. only produces consistency)
if mutations have the same effect regardless of the order they are applied
in.

That is my understanding anyway.

Mark

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