Re: add function for creating/attaching hash table in DSM registry

On Mon, Jun 30, 2025 at 01:29:22PM +0530, Rahila Syed wrote:
> /* XXX: Should we verify params matches what table was created with? */
>
> Are you planning to address the above before you commit? It seems like a
> helpful check since GetNamedDshash takes the params as arguments. That
> said, I don't have a strong preference either way.

I was not planning on this, primarily because I'm not sure about comparing
the function pointers. Note the following comment above the declaration of
dshash_parameters:

* Compare, hash, and copy functions must be supplied even when attaching,
* because we can't safely share function pointers between backends in general.
* The user data pointer supplied to the create and attach functions will be
* passed to these functions.

> I have a question: is there a way to remove the entries from the registry
> and free the space? For example, if a user decides to call
> dshash_destroy the dshash entry in the registry would no longer be
> needed.

See the following thread:

https://postgr.es/m/flat/CAAdDe3N%3Dj8mbkJJhmU6hTQRUXKEQMoJWsQz7JZyVK%3DrDWnVdiA%40mail.gmail.com

--
nathan