Hi Vsevolod, 1) Why such behavior? I thought any given SELECT request is handled by a limited subset of C* nodes and not by all of them, as per connection consistency/table replication settings, in case. When you run a query with allow filtering, Cassandra doesn't know where the data is located, so it has to go node by node, searching for the requested data.
2) Is it possible to forbid ALLOW FILTERING flag for given users/groups? I'm not familiar with such a flag. In my case, I just try to educate the R&D teams. Regards, On Wed, May 22, 2019 at 5:01 PM Vsevolod Filaretov <vsfilare...@gmail.com> wrote: > Hello everyone, > > We have an 8 node C* cluster with large volume of unbalanced data. Usual > per-partition selects work somewhat fine, and are processed by limited > number of nodes, but if user issues SELECT WHERE IN () ALLOW FILTERING, > such command stalls all 8 nodes to halt and unresponsiveness to external > requests while disk IO jumps to 100% across whole cluster. In several > minutes all nodes seem to finish ptocessing the request and cluster goes > back to being responsive. Replication level across whole data is 3. > > 1) Why such behavior? I thought any given SELECT request is handled by a > limited subset of C* nodes and not by all of them, as per connection > consistency/table replication settings, in case. > > 2) Is it possible to forbid ALLOW FILTERING flag for given users/groups? > > Thank you all very much in advance, > Vsevolod Filaretov. >
