### Description

This is to investigate what we could do to support the data streams in SQL. The backing indices can be queried already, but to address them similarly as they're queried over QDSL one would need to construct a pattern learned out of band and not through SQL metadata discovery mechanisms.
x-pack/plugin/ql/src/main/java/org/elasticsearch/xpack/ql/index/IndexResolver.java
}
                        if (createField) {
                            int dot = fieldName.lastIndexOf('.');
                            /*
                             * Looking up the "tree" at the parent fields here to see if the field is an alias.
                             * When the upper elements of the "tree" have no elements in fieldcaps, then this is an alias field. But not
                             * always: if there are two aliases - a.b.c.alias1 and a.b.c.alias2 - only one of them will be considered alias.
                             */
                            Holder<Boolean> isAliasFieldType = new Holder<>(false);
                            if (dot >= 0) {
                                String parentName = fieldName.substring(0, dot);
                                if (indexFields.flattedMapping.get(parentName) == null) {
                                    
                                    if (fieldCaps.get(parentName) == null) {
                                        isAliasFieldType.set(true);
                                    }
                                }
                            }
                            createField(
                                typeRegistry,
                                fieldName,
                                fieldCaps,
                                indexFields.hierarchicalMapping,
                                indexFields.flattedMapping,
                                s -> invalidField != null
                                    ? invalidField
                                    : createField(
                                        typeRegistry,
                                        s,
                                        typeCap.getType(),