Re: [HACKERS] proposal: schema variables

Pavel Stehule <pavel.stehule@gmail.com>

From: Pavel Stehule <pavel.stehule@gmail.com>

To: Arthur Zakirov <a.zakirov@postgrespro.ru>

Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>

Date: 2018-04-17T16:28:19Z

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 →

Move WAL sequence code into its own file
- a87987cafca6 19 (unreleased) cited
Add ExplainState argument to pg_plan_query() and planner().
- c83ac02ec730 19 (unreleased) cited
Don't include access/htup_details.h in executor/tuptable.h
- 1a8b5b11e48a 19 (unreleased) cited
Refactor to avoid code duplication in transformPLAssignStmt.
- b0fb2c6aa5a4 19 (unreleased) cited
Avoid including commands/dbcommands.h in so many places
- 325fc0ab14d1 19 (unreleased) cited
Restrict psql meta-commands in plain-text dumps.
- 71ea0d679543 19 (unreleased) cited
Split func.sgml into more manageable pieces
- 4e23c9ef65ac 19 (unreleased) cited
Fix squashing algorithm for query texts
- 0f65f3eec478 18.0 cited
EXPLAIN: Always use two fractional digits for row counts.
- 95dbd827f2ed 18.0 cited
Preliminary refactoring of plpgsql expression construction.
- a654af21ae52 18.0 cited
plpgsql: pure parser and reentrant scanner
- 7b27f5fd36cb 18.0 cited
Add some sanity checks in executor for query ID reporting
- 24f520594809 18.0 cited
Fix misleading error message context
- 4af123ad45bd 18.0 cited
Add macros for looping through a List without a ListCell.
- 14dd0f27d7cd 17.0 cited

Hi

2018-04-17 16:14 GMT+02:00 Arthur Zakirov <a.zakirov@postgrespro.ru>:

> Hello Pavel,
>
> On Thu, Oct 26, 2017 at 09:21:24AM +0200, Pavel Stehule wrote:
> > I hope so this proposal is good enough and simple.
> >
> > Comments, notes?
>
> As I understood variables are stored in pg_class table. Did you consider
> storing variables in a special catalog table? It can be named as
> pg_variable.
>
> pg_variable table requires more code of course, but it would fix the
> issues:
> - pg_class has a lot attributes which are not related with variables,
>   and I think variables don't need many of them
> - in a future variables might want to have some additional attributes
>   which are not needed for relations, you can easily add them to
>   pg_variable
>
> What do you think?
>

I though about it, and I am inclined to prefer pg_class instead separate
tables.

It true, so there are lot of "unused" attributes for this purpose, but
there is lot of shared attributes, and lot of shared code. Semantically, I
see variables in family of sequences, tables, indexes, views. Now, it
shares code, and I hope in next steps more code can be shared -
constraints, triggers.

There are two objective arguments for using pg_class:

1. unique name in schema - it reduces risk of collisions
2. sharing lot of code

So in this case I don't see well benefits of separate table.

Regards

Pavel

>
> --
> Arthur Zakirov
> Postgres Professional: http://www.postgrespro.com
> Russian Postgres Company
>