Re: [HACKERS] proposal: schema variables

Pavel Stehule <pavel.stehule@gmail.com>

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

To: Robert Haas <robertmhaas@gmail.com>

Cc: Arthur Zakirov <a.zakirov@postgrespro.ru>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>

Date: 2018-04-20T17:45:06Z

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

2018-04-20 17:32 GMT+02:00 Robert Haas <robertmhaas@gmail.com>:

> On Tue, Apr 17, 2018 at 12:28 PM, Pavel Stehule <pavel.stehule@gmail.com>
> wrote:
> > 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.
>
> I dunno, it seems awfully different to me.  There's only one "column",
> right?  What code is really shared here?  Are constraints and triggers
> even desirable feature for variables?  What would be the use case?
>

The schema variable can hold composite value. The patch allows to use any
composite type or adhoc composite values

DECLARE x AS compositetype;
DECLARE x AS (a int, b int, c int);

Constraints are clear, no.

Triggers are strange maybe, but why not - it can be used like enhanced
constraints, can be used for some value calculations, ..

> I think stuffing this into pg_class is pretty strange.
>

It will be if variable is just scalar value without any possibilities. But
then there is only low benefit

The access rights implementation is shared with other from pg_class too.

Regards

Pavel

>
> --
> Robert Haas
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>