In Cassandra you don't read-then-write updates, you just write the updates.
Sorry for being dense, but can you clarify a logical vs. physical row?
Batching is useful for reducing round trips to the server.
On 07/18/2012 06:18 AM, Leonid Ilyevsky wrote:
I have a question about efficiency of updates to a CF with composite key.
Let say I have 100 of logical rows to update, and they all belong to
the same physical wide row. In my naïve understanding (correct me if I
am wrong), in order to update a logical row, Cassandra has to retrieve
the whole physical row, add columns to it, and put it back. So I put
all my 100 updates in a batch and send it over. Would Cassandra be
smart enough to recognize that they all belong to one physical row,
retrieve it once, do all the updates and put it back once? Is my batch
thing even relevant in this case? What happens if I just send updates
one by one?
I want to understand why I should use batches. I don't really care
about one timestamp for all records, I only care about efficiency. So
I thought, I want to at least save on the number of remote calls, but
I also wonder what happens on Cassandra side.
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