[SOLR-11942] need better ref guide docs on join (and grouping) limitations in solr cloud

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: documentation
• Assignee: Unassigned
• Reporter: Chris M. Hostetter
• Created: 02/Feb/18 23:41
• Updated: 08/Jun/19 15:16

Description

on irc, a user asked about joining in solr cloud and i realized that the "JoinQParser" docs don't really clarify what does/doesn't work in cloud. There is a section on "Joining Across Collections" which points out some limitations in cloud mode, and the "Result Grouping" page has a brief note that "a...ll documents in each group must be co-located on the same shard in order for accurate counts to be returned. Document routing via composite keys can be a useful solution in many situations." But there is no similar warning for using the join parser n a single collection.

We should probably beef up the warning on the "Result Grouping" section to give an example of what does/doesn't work, and cross link to that from the "join" parser docs? (ie: "Note that when using multiple shards, the join parser has similar limitations as the GroupComponent regarding co-located documents|LINK_TO_OTHER_DOC )