New Query Language for Graph Databases to Become International Standard

Re:New Query Language for Graph Databases to Become Internat... by twic on Wednesday September 18, 2019 @01:34PM (#21007791)

Are you referring to recursive common table expressions? These do allow graph queries. They are quite different to the proprietary extensions, though, and much more awkward.

I would love to see SQL grow a concise navigation/join syntax like JPQL's [1]; imagine writing:

  select e.name, e.department.head.assistant.name from employees

Instead of:

  select e.name, a.name
  from employees e,
  join departments d using (department_id)
  join employees h on d.head_id = h.employee_id
  join employees a on h.assistant_id = a.employee_id

Given that dots already mean something in SQL, maybe it would have to be:

  select e.name, e->department->head->assistant.name from employees

Once you've got that, it would not be a huge leap to add a recursive version of this operator.

[1] https://www.objectdb.com/java/jpa/query/jpql/path#Navigation...

[ Parent | on HN ]

Re:New Query Language for Graph Databases to Become Internat... by dragonwriter on Wednesday September 18, 2019 @01:58PM (#21008077)

> I would love to see SQL grow a concise navigation/join syntax

Yeah, what you need is a specification of a name to use for the referenced table in implicit joins when you sepcify an FK, then if you reference the linked table, it performs the join (to bring in a different subthread, such an implicit join specification could be the mechanism of opting-in for index-free adjacency on that FK, too, so you'd combine syntactic support with the supporting query optimization.)

Maybe something like:

  REFERENCES <table> [(<key columns>)] AS <link-name>

So, your example would be be supported by (assuming all the FKs are to PKs so you don't need columns specified on the FKs):

  FOREIGN KEY department_id REFERENCES departments AS department

  FOREIGN KEY head_id REFERENCES employees AS head

  FOREIGN KEY assistant_id REFERENCES employees AS assistant

...on the relevant tables.

[ Parent | on HN ]