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From "Peter Schuller (Commented) (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-3868) Remove or nullify replicate_on_write option
Date Thu, 23 Feb 2012 10:33:48 GMT


Peter Schuller commented on CASSANDRA-3868:

I completely agree about not adding more counter-specific code.

I still think it is a very useful feature to retain, for the same reasons as before. I'm not
suggesting running with it in general, but it is an extremely effective pressure release valve
for large data size counter clusters - keeping in mind in particular that counters are, in
addition to being potentially very expensive due to reading, non-idempotent and unsafe to
re-try. A cluster even "slightly" overloaded or misbehaving to the point of causing timeouts
is effectively causing you to drop increments (or overcount if you "incorrectly" retry). In
other words, it's fairly easy to end up in a position where you might prefer running with
replicate on write turned off for a few minutes/hours while you fix something; much more so
than with normal writes.

So in summary, the sensitivity to timeouts with counters from the client's perspective, in
combination with the easy with which you can get into temporary capacity issues due to read-on-write,
makes it, in my opinion, a useful thing to retain.

> Remove or nullify replicate_on_write option
> -------------------------------------------
>                 Key: CASSANDRA-3868
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 0.8.0
>            Reporter: Brandon Williams
>             Fix For: 1.1.0
>         Attachments: 3868.txt
> My understanding from Sylvain is that setting this option to false is rather dangerous/stupid,
and you should basically never do it.  So 1.1 is a good time to get rid of it, or make it
a no-op.

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