Horton

Re: Schema variables - new implementation for Postgres 15

Julien Rouhaud <rjuju123@gmail.com>

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From: Julien Rouhaud <rjuju123@gmail.com>
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: Dean Rasheed <dean.a.rasheed@gmail.com>, Joel Jacobson <joel@compiler.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-01-23T08:10:34Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Allow underscores in integer and numeric constants.

  2. Remove special outfuncs/readfuncs handling of RangeVar.catalogname.

  3. Remove extra space from dumped ALTER DEFAULT PRIVILEGES.

  4. Create FKs properly when attaching table as partition

  5. psql: improve tab-complete's handling of variant SQL names.

Hi,

On Fri, Jan 21, 2022 at 09:23:34PM +0100, Pavel Stehule wrote:
> 
> I am sending updated patches

I've been looking a bit deeper at the feature and I noticed that there's no
locking involved around the session variable usage, and I don't think that's
ok.  AFAICS any variable used in a session will be cached in the local hash
table and will never try to access some catalog or cache, so I don't have any
naive scenario that would immediately crash, but this has some other
implications that seems debatable.

For instance, right now nothing prevents a variable from being dropped while
another session is using it.

Obviously we can't lock a session variable forever just because a session
assigned a value once ages ago, especially outside of the current transaction.
But if a session set a variable in the local transaction, I don't think that
it's ok to have a subsequent query failing because someone else concurrently
dropped the variable.

I only backlogged this current thread but I didn't see that being discussed.