deleteById for collection with composite router and routing.field - is this sufficient solution?

[Jaroslaw Rozanski <me...@jarekrozanski.eu>]

Hi all,

Facing issues with delete by ID in Solr 5.5.5 (but it looks like it 
affects version as high as 7.5.x and possibly newer). Collection uses 
composite router with routing field set to field *other than* unique key.

In the above set-up the SolrJ .deleteByQuery works fine albeit is very 
slow (high load, large index, etc). However the .deleteById is not 
working correctly. The delete by ID, even when "route" param is provided 
yields: "missing _version_ on update from leader".

That does correlate with https://issues.apache.org/jira/browse/SOLR-7384.


In the org.apache.solr.cloud.FullSolrCloudDistribCmdsTest (5.5.5 release 
tag)

these tests are commented out:

     // See SOLR-7384
     //    testDeleteByIdImplicitRouter();
     //    testDeleteByIdCompositeRouterWithRouterField();

I followed suggestion from 
https://issues.apache.org/jira/browse/SOLR-12694 and arrived at this in:

org.apache.solr.client.solrj.request.JavaBinUpdateRequestCodec (starting 
from line #220)

         if (params != null) {
           Long version = getVersion(params);
           if (params.containsKey(UpdateRequest.ROUTE)) {
             // WAS updateRequest.deleteById(entry.getKey(), (String) 
params.get(UpdateRequest.ROUTE));
             updateRequest.deleteById(entry.getKey(), (String) 
params.get(UpdateRequest.ROUTE), version);
           } else {
             updateRequest.deleteById(entry.getKey(), version);
           }
         } else {
           updateRequest.deleteById(entry.getKey());
         }


With the above, by setting version on deserialized UpdateRequest the 
previously commented out tests pass once again.

Now, the question is: *Is this correct approach?*
If I am reading this correctly, this change means that the version 
deleted on the leader is passed to the replicas. But should it? Is the 
version always consistent between leader and replica (except for out of 
sync state)?


Thanks,
Jaroslaw


-- 
Jaroslaw Rozanski | e: me@jarekrozanski.eu