Re: [HACKERS] proposal: schema variables

Hi

2018-02-07 7:34 GMT+01:00 Pavel Stehule <pavel(dot)stehule(at)gmail(dot)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