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Posted to user@cassandra.apache.org by amit sehas <cu...@yahoo.com.INVALID> on 2019/02/05 15:45:07 UTC
coordinator failure handling
Sorry to bother you, i am just starting to look into Cassandra, and am confused about a lot of things.
If a client sends a query to a coordinator, then if it does not receive a response from the co-ordinator then:
a) is there a timeout at which client retries the query?b) is there somewhere we can specify the timeout?c) will it resend the query to the same co-ordinator, if not then how does it determine which coordinators to send it to?
thanks
Re: coordinator failure handling
Posted by Tom Wollert <to...@codeweavers.net>.
All below AFAIK
a) The query will only be retried after half the timeout has passed, if the
query is idempotent (you have to set that on prepare statement, otherwise
it will assume it isn't)
b) Querytimeout can be set globally in the
Cluster.Builder().WithQueryTimeout
c) The LoadBalancingPolicy should handle that. Generally use
TokenAwarePolicy it should round robin through nodes that are responsible
for the data you are trying to save/access
On Tue, 5 Feb 2019 at 15:45, amit sehas <cu...@yahoo.com.invalid> wrote:
> Sorry to bother you, i am just starting to look into Cassandra, and am
> confused about a lot of things.
>
> If a client sends a query to a coordinator, then if it does not receive a
> response from the co-ordinator then:
>
> a) is there a timeout at which client retries the query?
> b) is there somewhere we can specify the timeout?
> c) will it resend the query to the same co-ordinator, if not then how does
> it determine which coordinators to send it to?
>
> thanks
>
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Re: coordinator failure handling
Posted by Eric Stevens <mi...@gmail.com>.
This will depend on what driver you're using at the client. The Java
driver, for example, has ways to configure each of the things you
mentioned, with a variety of implementations you can choose from. There
are also ways to provide your own custom implementation if you don't like
the options available.
On Tue, Feb 5, 2019 at 8:45 AM amit sehas <cu...@yahoo.com.invalid> wrote:
> Sorry to bother you, i am just starting to look into Cassandra, and am
> confused about a lot of things.
>
> If a client sends a query to a coordinator, then if it does not receive a
> response from the co-ordinator then:
>
> a) is there a timeout at which client retries the query?
> b) is there somewhere we can specify the timeout?
> c) will it resend the query to the same co-ordinator, if not then how does
> it determine which coordinators to send it to?
>
> thanks
>