Allow LIMIT subclause on all read-only clauses

[Mats-SX]

CIR-2017-194

Cypher's LIMIT subclause is currently applicable to the WITH and RETURN clauses only. It would be a nice feature to be able to support LIMIT directly on MATCH as well, reducing the currently mandated WITH * to be inserted in between. Compare the following two queries for an example:

MATCH (s:Source)
WITH * LIMIT 10
CREATE (s)-[:T]->(:Target)

vs

MATCH (s:Source)
LIMIT 10
CREATE (s)-[:T]->(:Target)

I see little reason to not extend this to UNWIND as well, in order to more easily define the rule that determines where LIMIT is allowed: all read-only clauses.

LIMIT will not affect the side effects of preceding updating clauses, which makes it unfit as a subclause for them. Allowing LIMIT on all read-only clauses could make this semantics more visible.

An extension of this CIR could be to define the same rule for SKIP.