[SOLR-10157] JSON Facets should give more helpful error msg when users attempt to an unknown aggregation

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 8.6
• Component/s: Facet Module
• Assignee: Munendra S N
• Reporter: Chris M. Hostetter
• Created: 17/Feb/17 22:19
• Updated: 15/Jul/20 15:09
• Resolved: 18/Mar/20 05:50

Description

Sample question from a confused solr-user email...

> I'm getting this error when I tried to do a division in JSON Facet.
>
>   "error":{
>     "msg":"org.apache.solr.search.SyntaxError: Unknown aggregation agg_div in ('div(4,2)', pos=4)",
>     "code":400}}
>
>
> Is this division function supported in JSON Facet?

And the subsequent followup from the same user...

I found that we can't put div(4,2) directly, as it wouldn't work.

It will work if I put something like max(div(4,2)).

---

It seems like a better error handline code path for FunctionQParser.parseAgg (once we've confirmed no such aggregation exists) would be:

• attempt to parse the original string as a regular (non-Agg)ValueSource) function
  • if that succeeds, give the user an error indicating that this ValueSource must be wrapped in an aggregation
  • if it fails, continue to throw the original error
• either way, any error thrown should refer to the original id before

For example:

• div(price,popularity) should throw an error with a msg along the lines of: 'div' is a per-document function, not a multi-document aggregation function, input: div(price,popularity)
• HOSS(price,popularity) on the other hand should throw an error such as: Unknown aggregation HOSS in ('HOSS(price,populaity)' ...
  • note the message cites HOSS not agg_HOSS