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