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From Jools <>
Subject Inserting new data, where the key points to a tombstone record.
Date Wed, 09 Jun 2010 08:38:38 GMT

I've been developing a system against cassandra over the last few weeks, and
I'd like to ask the community some advice on the best way to deal with
inserting new data where the key is currently a tombstone record.

As with all distributed systems, this is always a tricky thing to deal with,
so I though I'd throw it to a wider audience.

1) insert new record.
2) deleted record.
3) insert record with same key as deleted record.

Now I know I can make this work if I flush and compact between 2 and 3.
However, I don't want to rely on a flush and compact and I'd like to code
defensively against this senario, and I've ended up looking up to see if the
key exists, then if it does then I know I can't insert the data. However, if
the key does not exist then I attempt an insert.

Now, here lies the issue. If I have more than one client doing this at the
same time, both trying to insert using the same key. One will succeed and
ones will fail. However neither insert will give me an indication of which
one actually succeeded.

So should an insert against an existing key, or deleted key produce some
kind of exception ?



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