Stefan Genov created CASSANDRA-15621:
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Summary: LOCAL_QUORUM is waiting on remote datacenter
Key: CASSANDRA-15621
URL: https://issues.apache.org/jira/browse/CASSANDRA-15621
Project: Cassandra
Issue Type: Bug
Reporter: Stefan Genov
We have a 2 datacenters ( One in EU and one in US ) cluster with 4 nodes each
deployed in AWS.
The nodes are separated in 3 racks ( Availability zones ) each.
In the cluster we have a keyspace test with replication:
NetworkTopologyStrategy, eu-west:3, us-east:3
In the keyspace we have a table called mytable that has only one row 'id' text
Now, we were doing some tests on the performance of the database.
In CQLSH with a consistency level of LOCAL_QUORUM we were doing some inserts
with TRACING ON and we noticed that the requests were not working as we
expected them.
>From the tracing data we found out that the coordinator node was hitting as
>expected 2 other local nodes and was also sending a request to one of the
>remote datacenter nodes. Now the problem here was that the coordinator was
>waiting not only for the local nodes ( who finished in no time ) but for the
>remote nodes too.
Now since our 2 datacenters are geographically far away from each other, our
requests were taking a very long time to complete.
Notes:
- This does not happen with DSE but our understanding was we don't need to pay
crazy money for LOCAL_QUORUM to work as is expected
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