ESQL: Ensure we fail nicely for invalid INLINESTATS queries

[alex-spies]

Examples:

• INLINESTATS with CATEGORIZE (c.f. ESQL: INLINESTATS with CATEGORIZE in the BY clause #124717)
• INLINESTATS with SORT (Error when using INLINESTATS after SORT on snapshot build #113727)
• INLINESTATS with no aggregates, e.g. INLINESTATS BY group, expr = foo(...)
• INLINESTATS in CCQ scenarios (c.f. ESQL: Make INLINESTATS work in CCQ #124748)

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[kanoshiou]

Hi! 👋

I’d love to tackle this issue, but I could use some additional guidance on INLINESTATS in CCQ scenarios. Specifically, I’d like to understand how to trigger this failure and any other insights that could help me grasp the issue better. Thank you so much!

[luigidellaquila]

Hi @kanoshiou

With CCQ (cross-cluster queries, or more precisely CCS - cross-cluster search) we mean queries that involve multiple clusters, eg. with FROM cluster1:foo*,cluster2:bar* | ....

You'll need a multi-cluster ES configuration of course.

See also MultiClustersIT and MultiClusterSpecIT

[alex-spies]

@kanoshiou thanks a lot for offering help!

INLINESTATS is still pretty under construction and may change dramatically going forward; for this reason, I don't think this task is really ready to be worked on just yet.

[kanoshiou]

Thank you for sharing the information @luigidellaquila @alex-spies!

I'll leave this aside for now and focus on resolving other issues.