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Posted to issues@solr.apache.org by "wei wang (Jira)" <ji...@apache.org> on 2021/06/13 23:41:00 UTC

[jira] [Comment Edited] (SOLR-15472) shards.preference should support leader=false

    [ https://issues.apache.org/jira/browse/SOLR-15472?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17362669#comment-17362669 ] 

wei wang edited comment on SOLR-15472 at 6/13/21, 11:40 PM:
------------------------------------------------------------

We are also exploring the performance impact of excluding reads from the leader node.  In initial testing with 2 TLOG replicas + 6 PULL replicas set up, overall query throughput is improved especially when update load is heavy.  Here we can config 

shards.preference=replica.leader:false

So the leader TLOG node is excluded from reads, while the other non-leader TLOG takes the same query load as the PULL replicas.  It is compatible with existing routing options such as replica.type and replica.location.  

The benefit of replica.leader option is that in this set up, we are able to exclude the query load from only one node.  If we use replica.type=PULL,  both of the 2 TLOG replicas do not handle queries, meaning 25% of query capacity is lost.  Also having only 1 TLOG replicas per shard is not acceptable for the production environment. With replica.leader=false, we only lose 12.5% of query capacity and still have a backup TLOG node per shard. 


was (Author: weiwang19):
We are also exploring the performance impact of excluding reads from the leader node.  In initial testing with 2 TLOG replicas + 6 PULL replicas set up, overall query throughput is improved especially when update load is heavy.  Attach the patch tested. 

> shards.preference should support leader=false
> ---------------------------------------------
>
>                 Key: SOLR-15472
>                 URL: https://issues.apache.org/jira/browse/SOLR-15472
>             Project: Solr
>          Issue Type: Bug
>      Security Level: Public(Default Security Level. Issues are Public) 
>          Components: query
>            Reporter: Stephen Lewis Bianamara
>            Priority: Major
>         Attachments: SOLR-15472.patch
>
>
> The shards.preference command controls SOLR read request routing. But it doesn't currently support a property to exclude leaders from reads, e.g.
> shards.preference=leaders:false
> or
> shards.preference=followers
>  



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