[SOLR-9566] Can we avoid doing recovery when collections are first created?

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 6.3
• Assignee: Alan Woodward
• Reporter: Alan Woodward
• Created: 26/Sep/16 12:57
• Updated: 08/Jun/19 15:32
• Resolved: 18/Oct/16 08:34

Description

When a core starts up as part of a collection, and it's not a shard leader, it goes into recovery, part of which involves a 7 second wait (set in SOLR-7141) to ensure that updates being sent from the leader don't get missed in between buffering and replication.

This has the unfortunate side-effect of adding a 7-second pause to collection creation whenever the replication factor is 2 or more, which slows down tests massively - for example, DeleteReplicaTest takes about 54 seconds to execute on my machine, 28 seconds of which is just pauses - over 50% of execution time. It's not actually possible to add documents to a collection before the creation request has returned, so the recovery stage here isn't strictly speaking necessary.

I think we could try adding a parameter to a CoreAdmin create request that says the core is being created as part of a new collection, so it doesn't need to try and recover from it's leader when it starts up. Does this sound sensible, or am I missing something here?

Issue Links

• relates to: SOLR-11661 New HDFS collection reuses unremoved data from a deleted HDFS collection with same name causes inconsistent view of documents