Re: [SQL/PGQ] Custom executor node for VLE

Hi,

On 2026-07-21 16:06:55 +0200, Henri GASC wrote:
> From what I understand, graph queries are rewritten into JOIN queries in order
> to use the complete machinery available for optimization.

> However, only single hop are currently allowed. While more complex queries are
> parsed, an error is raised by the executor if it encounter this situation.
> VLE are not allowed at all, and we are missing the capabilities to support
> TRAIL/SIMPLE/ACYCLIC syntax, as well as SHORTEST and other selective path
> search prefixes.
>
> My plan was to keep the query rewriting for fixed-depth, and switch to the
> custom executor in case of VLE, with VLE following the strategy from Henson
> Choi ([1]) (with the correct syntax for the queries).
>
> However, it seems a rather complex thing to keep with query rewriting,

FWIW, I continue to believe that choosing to implement something like PGQ in
the rewriter is architecturally wrong:
https://postgr.es/m/20240216192301.q2tf4bqjydymg3g2%40awork3.anarazel.de

Greetings,

Andres Freund