Horton

Re: proposal: schema variables

Pavel Stehule <pavel.stehule@gmail.com>

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From: Pavel Stehule <pavel.stehule@gmail.com>
To: Wolfgang Walther <walther@technowledgy.de>
Cc: Dmitry Dolgov <9erthalion6@gmail.com>, Laurenz Albe <laurenz.albe@cybertec.at>, Erik Rijkers <er@xs4all.nl>, Michael Paquier <michael@paquier.xyz>, Amit Kapila <amit.kapila16@gmail.com>, DUVAL REMI <REMI.DUVAL@cheops.fr>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-11-16T15:36:19Z
Lists: pgsql-hackers, pgsql-performance

Commits

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

  1. Move WAL sequence code into its own file

  2. Add ExplainState argument to pg_plan_query() and planner().

  3. Don't include access/htup_details.h in executor/tuptable.h

  4. Refactor to avoid code duplication in transformPLAssignStmt.

  5. Avoid including commands/dbcommands.h in so many places

  6. Restrict psql meta-commands in plain-text dumps.

  7. Split func.sgml into more manageable pieces

  8. Fix squashing algorithm for query texts

  9. EXPLAIN: Always use two fractional digits for row counts.

  10. Preliminary refactoring of plpgsql expression construction.

  11. plpgsql: pure parser and reentrant scanner

  12. Add some sanity checks in executor for query ID reporting

  13. Fix misleading error message context

  14. Add macros for looping through a List without a ListCell.

so 16. 11. 2024 v 15:56 odesílatel Wolfgang Walther <walther@technowledgy.de>
napsal:

> Dmitry Dolgov:
> > This sounds to me like an argument against allowing name clashing between
> > variables and tables. It makes even more sense, since session variables
> are in
> > many ways similar to tables.
>
> +1
>

It doesn't help too much, because the unique tuple (schema, name), and
there is a search path.

Secondly, the pg_class is not good enough for description of scalar
variables, and enhancing pg_class for scalar variables can be messy.



>
> My mental model of a session variable is similar to a single-row,
> optionally global temporary, table.
>
> Is there any substantial difference that I am not aware of?
>

What I know, the variables are used as query parameters, not as relations -
Oracle, DB2, MSSQL, MySQL, ...

semantically, yes - it is a global temporary object, but  it can be scalar
or composite value - it is not row.

(global (temp)) table can hold 0, 1 or more rows (and rows are always
composite of 0..n fields). The variable holds a value of some type.
Proposed session variables are like plpgsql variables (only with different
scope). In Postgres there is a difference between a scalar variable and
composite variable with one field.

Regards

Pavel


> Best,
>
> Wolfgang
>