Horton

Re: Schema variables - new implementation for Postgres 15

Julien Rouhaud <rjuju123@gmail.com>

View thread
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: 2022-01-25T08:48:21Z
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 Tue, Jan 25, 2022 at 09:35:09AM +0100, Pavel Stehule wrote:
> út 25. 1. 2022 v 6:18 odesílatel Julien Rouhaud <rjuju123@gmail.com> napsal:
> 
> > I think the lock should be
> > acquired during IdentifyVariable.  It should probably be optional as one
> > codepath only needs the information to raise a warning when a variable is
> > shadowed, so a concurrent drop isn't a problem there.
> >
> 
> There is a problem, because before the IdentifyVariable call I don't know
> if the variable will be shadowed or not.
> 
> If I lock a variable inside IdentifyVariable, then I need to remember if I
> did lock there, or if the variable was locked already, and If the variable
> is shadowed and if lock is fresh, then I can unlock the variable.

But in transformColumnRef() you already know if you found a matching column or
not when calling IdentifyVariable(), so you know if an existing variable will
shadow it right?

Couldn't you call something like

    lockit = node == NULL;
	varid = IdentifyVariable(cref->fields, &attrname, &not_unique, lockit);

The only other caller is transformLetStmt(), which should always lock the
variable anyway.