I was aware of the read-then-write pattern for counters, but not
secondary indexes. I'll have to take a look into that.
Thanks.
On 07/20/2012 02:32 AM, aaron morton wrote:
I'm assuming the logical row is in a CQL 3 CF with composite
PRIMARYKEY http://www.datastax.com/dev/blog/whats-new-in-cql-3-0
It will still be a no look write. The exception being secondary
indexes and counters which include reads in the write path.
Cheers
-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com
On 20/07/2012, at 10:26 AM, Kirk True wrote:
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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