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From Ayub M <>
Subject Cassandra lightweight transactions failing
Date Wed, 16 Jan 2019 02:08:20 GMT
There are 2 DCs each with 3 nodes, and the RF used for writes is 2 and
reads its each_quorum. A lightweight transaction is used to ensure
consistency of updates across DCs. Now what is happening is for certain
records, hundreds (maybe thousands) of lwt updates are hitting the cluster
around same time. What is happening is that all of these updates are
failing with "Operation timed out - received only 0 responses", not even
one attempt is able to change the status of that one record and its making
everyone else fail. Ideally it would be better for the first attempt to go
through the update and change the values so that subsequent lwt updates
will not go through since the lwt values do not satisfy. Is there any way
to achieve this?

Tried increasing cas_contention timeout but this not help except making all
the transactions wait longer before failing. Used "local consistency" which
made lwt run faster but this would not help in our case since we want
strong consistency on both the DCs. Any alternatives?

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