Re: [HACKERS] proposal: schema variables

Hi

I am sending new update. The code is less ugly, and the current
functionality is +/- final for first stage. It should be good enough for
playing and testing this concept.

What is supported:

1. scalar, composite and array variables
2. composite can be defined on place or some composite type can be used
3. variable, or any field of variable, can have defined default value
4. variable is database object - the access rights are required
5. the values are stored in binary form with defined typmod

An usage is very simple:

postgres=# create variable foo as numeric default 0;
CREATE VARIABLE
postgres=# select foo;
┌─────┐
│ foo │
╞═════╡
│ 0 │
└─────┘
(1 row)

postgres=# let foo = pi();
LET
postgres=# select foo;
┌──────────────────┐
│ foo │
╞══════════════════╡
│ 3.14159265358979 │
└──────────────────┘
(1 row)

postgres=# create variable boo as (x numeric default 0, y numeric default
0);
CREATE VARIABLE
postgres=# let boo.x = 100;
LET
postgres=# select boo;
┌─────────┐
│ boo │
╞═════════╡
│ (100,0) │
└─────────┘
(1 row)

postgres=# select boo.x;
┌─────┐
│ x │
╞═════╡
│ 100 │
└─────┘
(1 row)

Please try it.

Regards

Pavel