[
https://issues.apache.org/jira/browse/SOLR-2358?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13123231#comment-13123231
]
Ted Dunning commented on SOLR-2358:
-----------------------------------
Mark,
How do you handle failure scenarios?
The failures I am curious about are:
- the leader fails, but a transaction is still sent to it because the client
didn't get the memo in time
- the leader fails but has already written a transaction locally without having
a chance to forward it to the followers
- the leader fails after writing locally and to the replicas but before sending
an ACK
- a replica is partitioned from the cluster, a transaction is received and
committed by all live replicas and then the failed index returns from the land
of the living dead.
The bad behaviors that need to be avoided include
- document acked but not inserted
- document not acked, inserted again and two copies wind up in the index
- indexes diverge because some replicas commit a change while others do not
Two phase commit is not generally a viable solution for this in a cluster where
failures can occur because it requires locks to be taken. Once these locks are
taken, the cluster cannot proceed until the locks are cleared and this cannot
be done reliably in the presence of failures.
Zookeeper avoids this to a large degree by making updates idempotent before
they are inserted into the update queue. This means that if the updates are
done more than once, most importantly during error recovery, that no error
actually occurs. This is what makes ZK able to take snapshots without stopping
the world. It does not entirely resolve the case of transactions that are
committed but not acked.
> Distributing Indexing
> ---------------------
>
> Key: SOLR-2358
> URL: https://issues.apache.org/jira/browse/SOLR-2358
> Project: Solr
> Issue Type: New Feature
> Components: SolrCloud, update
> Reporter: William Mayor
> Priority: Minor
> Fix For: 4.0
>
> Attachments: SOLR-2358.patch
>
>
> The first steps towards creating distributed indexing functionality in Solr
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
