Horton

Re: Schema variables - new implementation for Postgres 15

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: Tomas Vondra <tomas.vondra@enterprisedb.com>, Jaime Casanova <jcasanov@systemguards.com.ec>, Erik Rijkers <er@xs4all.nl>, Gilles Darold <gilles@darold.net>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Michael Paquier <michael@paquier.xyz>, Amit Kapila <amit.kapila16@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Tom Lane <tgl@sss.pgh.pa.us>, Alvaro Herrera <alvherre@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>
Date: 2021-11-06T14:57:14Z
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.

On Sat, Nov 06, 2021 at 04:45:19AM +0100, Pavel Stehule wrote:
> st 3. 11. 2021 v 14:05 odesílatel Tomas Vondra <tomas.vondra@enterprisedb.com> napsal:
> > 1) Not sure why we need to call this "schema variables". Most objects
> > are placed in a schema, and we don't say "schema tables" for example.
> > And it's CREATE VARIABLE and not CREATE SCHEMA VARIABLE, so it's a bit
> > inconsistent.

+1

At least the error messages need to be consistent.
It doesn't make sense to have both of these:

+               elog(ERROR, "cache lookup failed for schema variable %u", varid);
+               elog(ERROR, "cache lookup failed for variable %u", varid);

> Yes, there is inconsistency, but I think it is necessary. The name
> "variable" is too generic. Theoretically we can use other adjectives like
> session variables or global variables and the name will be valid. But it
> doesn't describe the fundamentals of design. This is similar to the
> package's variables from PL/SQL. These variables are global, session's
> variables too. But the usual name is "package variables". So schema
> variables are assigned to schemes, and I think a good name can be "schema
> variables". But it is not necessary to repeat keyword schema in the CREATE
> COMMAND.
> 
> My opinion is not too strong in this case, and I can accept just
> "variables" or "session's variables" or "global variables", but I am not
> sure if these names describe this feature well, because still they are too
> generic. There are too many different implementations of session global
> variables (see PL/SQL or T-SQL or DB2).

I would prefer "session variable".

To me, this feature seems similar to a CTE (which exists for a single
statement), or a temporary table (which exists for a single transaction).  So
"session" conveys a lot more of its meaning than "schema".

But don't rename everything just for me...

-- 
Justin