conditional delete consistency level/timeout

[Mohica Jasha <mo...@gmail.com>]

Earlier I reported the following bug against C* 2.0.5
https://issues.apache.org/jira/browse/CASSANDRA-7176
It seems to be fixed in C* 2.0.7, but we are still seeing similar
suspicious timeouts.

We have a cluster of C* 2.0.7, DC1:3, DC2:3

We have the following table:
CREATE TABLE conditional_update_lock (
  resource_id text,
  lock_id uuid,
  PRIMARY KEY (resource_id)
)

We noticed that DELETE queries against this table sometimes timeout:

A sample raw query executed through datastax java-driver 2.0.1 which timed
out:
DELETE from conditional_update_lock where resource_id =
'STUDY_4234234.324.470' IF lock_id = da2dd547-e807-45de-9d8c-787511123f3c;

java-driver throws
com.datastax.driver.core.exceptions.ReadTimeoutException: Cassandra timeout
during rea query at consistency LOCAL_QUORUM (2 responses were required but
only 1 replica responded)

We set LOCAL_SERIAL and LOCAL_QUORUM as serial consistency level and
consistency level in the query option passed to datastax Cluster.Builder.
In my understanding the above query should be executed in LOCAL_SERIAL
consistency level, I wonder why the exception says it failed to run the
query in the LOCAL_QUORUM consistency level?

We are running a large number of queries against different tables in our
cassandra cluster but only the above one times out often. I wonder if there
is anything inefficient/buggy in the implementation of conditional delete
in cassandra?

Mohica

Re: conditional delete consistency level/timeout

[Robert Coli <rc...@eventbrite.com>]

On Fri, May 16, 2014 at 7:06 AM, Mohica Jasha <mo...@gmail.com>
wrote:

> Earlier I reported the following bug against C* 2.0.5
>
    ...

> It seems to be fixed in C* 2.0.7, but we are still seeing similar
> suspicious timeouts.
>
    ...

> We noticed that DELETE queries against this table sometimes timeout:
>
   ...

> We set LOCAL_SERIAL and LOCAL_QUORUM as serial consistency level and
> consistency level in the query option passed to datastax Cluster.Builder.
> In my understanding the above query should be executed in LOCAL_SERIAL
> consistency level, I wonder why the exception says it failed to run the
> query in the LOCAL_QUORUM consistency level?
>

I swear I have seen a similar relevant bug in JIRA recently... did you
ultimately file one?

=Rob