Re: [HACKERS] proposal: schema variables

Pavel Stehule <pavel.stehule@gmail.com>

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

To: "David G. Johnston" <david.g.johnston@gmail.com>, Pavel Luzanov <p.luzanov@postgrespro.ru>

Cc: Pavel Golub <pavel@gf.microolap.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>

Date: 2018-03-08T18:00:36Z

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

Attachments

schema-variables-poc-180308-01-diff (application/octet-stream)

Hi

2018-02-07 7:34 GMT+01:00 Pavel Stehule <pavel.stehule@gmail.com>:

> Hi
>
> updated patch with your changes in documentation and pg_dump (initial)
> support
>
> Main issue of this patch is storage. We can reuse local buffers used for
> temp tables. But it does allocation by 8KB and it creates temp files for
> every object. That is too big overhead. Storing just in session memory is
> too simple - then there should be lot of new code used, when variable will
> be dropped.
>
> I have ideas how to allow work with mix of scalar and composite types - so
> it will be next step of this prototype.
>
> Regards
>
> Pavel
>

new update - rebased, + some initial support for composite values on right
side and custom types, arrays are supported too.

omega=# CREATE VARIABLE xx AS (a int, b numeric);
CREATE VARIABLE
omega=# LET xx = (10, 20)::xx;
LET
omega=# SELECT xx;
+---------+
|   xx    |
+---------+
| (10,20) |
+---------+
(1 row)

omega=# SELECT xx.a + xx.b;
+----------+
| ?column? |
+----------+
|       30 |
+----------+
(1 row)

omega=# \d xx
schema variable "public.xx"
+--------+---------+
| Column |  Type   |
+--------+---------+
| a      | integer |
| b      | numeric |
+--------+---------+


Regards

Pavel