
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
}
            }
            
            for (NamedExpression agg : aggs) {
                Expression e = agg instanceof Alias a ? a.child() : agg;
                if (e instanceof SurrogateExpression sf) {
                    changed = true;
                    Expression s = sf.surrogate();
                    
                    if (s instanceof AggregateFunction == false) {
                        
                        var surrogateWithRefs = s.transformUp(AggregateFunction.class, af -> {
                            
                            
                            var attr = aggFuncToAttr.get(af);
                            
                            if (attr == null) {
                                var temporaryName = temporaryName(agg, af);
                                
                                var newAlias = new Alias(agg.source(), temporaryName, null, af, null, true);
                                attr = newAlias.toAttribute();
                                aggFuncToAttr.put(af, attr);
                                newAggs.add(newAlias);
                            }
                            return attr;
                        });
                        
                        
                        
                        var aliased = new Alias(agg.source(), agg.name(), null, surrogateWithRefs, agg.toAttribute().id());