
Filing this issue to track a question/comment that was raised by @ywangd  here https://github.com/elastic/elasticsearch/pull/98309#discussion_r1294115440

One question I do have is why we chose to [execute the LookupRequest with the enrich origin](https://github.com/elastic/elasticsearch/blob/2e4440ff1c0decf79f8a40688566411f7d518aa7/x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/enrich/EnrichLookupService.java#L141C2-L141C2). It means the following query works when the user has access to only the playlist index without access to either the songs enrich policy or its associated index.

```
FROM playlist | ENRICH songs ON song_id
```

It feels a bit weird to me that we have no control on who can use what enrich process. That said, we don't have a good story around enrich and ingest pipeline either, i.e. we have no control over who can use what pipeline where a pipeline can contain an enrich processor. There have been quite a few complaints from users and we have an https://github.com/elastic/elasticsearch/issues/57586 for it. I wonder whether we should not repeat the problem here with ES|QL. On the surface, it might be easier to tackle compared to ingest pipelines since ES|QL is read-only and has no "bulk" operations. What do you think?
x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/optimizer/LogicalPlanOptimizer.java
if (l2 <= l1) {
                            return new Limit(limit.source(), Literal.of(limit.limit(), l2), limit.child());
                        }
                    }
                }
            }
            return limit;
        }
        /**
         * Checks the existence of another 'visible' Limit, that exists behind an operation that doesn't produce output more data than
         * its input (that is not a relation/source nor aggregation).
         * P.S. Typically an aggregation produces less data than the input.
         */
        private static Limit descendantLimit(UnaryPlan unary) {
            UnaryPlan plan = unary;
            while (plan instanceof Aggregate == false) {
                if (plan instanceof Limit limit) {
                    return limit;
                }
                if (plan.child() instanceof UnaryPlan unaryPlan) {
                    plan = unaryPlan;
                } else {
                    break;
                }
            }
            return null;
        }
    }
    
    public static class SplitInWithFoldableValue extends OptimizerRules.OptimizerExpressionRule<In> {