Hi kurt, thanks for responding.
I understand that that query is very resource consuming. My question was
why I only see its effect on the same node? considering that I have a
replication factor of 2, I was hoping to see this load evenly
distributed among those 2 nodes. That query runs hundreds of time on
each run, but the loads seems to be always on the node2. That is what I
am trying to figure out.
On 09/11/2017 06:25 PM, kurt greaves wrote:
Your first query will effectively have to perform table scans to satisfy
what you are asking. If a query requires ALLOW FILTERING to be
specified, it means that Cassandra can't really optimise that query in
any way and it's going to have to query a lot of data (all of it...) to
satisfy the result.
Because you've only specified one attribute of the partitioning key,
Cassandra doesn't know where to look for that data, and will need to
query all of it to find partitions matching that restriction.
If you want to select distinct you should probably do it in a
distributed manner using token range scans, however this is generally
not a good use case for Cassandra. If you really need to know your
partitioning keys you should probably store them in a separate cache.
--
Kaveh Minooie
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