Re: Emulating trigger BEFORE SELECT behavior

On Thu, Apr 18, 2013 at 11:02 AM, Atri Sharma <atri(dot)jiit(at)gmail(dot)com> wrote:

>
> [...]
>
> One way I was thinking of was creating an updatable view, which is
> initialized to NULL. As SELECT queries take place, I can update the
> view to include the new rows.
>
>
Why you just create your track function and a view to call it?

Example:

BEGIN;

CREATE TABLE foo (id SERIAL PRIMARY KEY, data TEXT);
CREATE TABLE foo_track(tracktime TIMESTAMP DEFAULT now(), foo_row foo);

INSERT INTO foo (data) SELECT 'Some Data'||id FROM generate_series(1,10) AS
id;

CREATE OR REPLACE FUNCTION foo_track_func(foo) RETURNS integer AS
$$
INSERT INTO foo_track(foo_row) VALUES ($1) RETURNING (foo_row).id
$$
LANGUAGE sql;

CREATE VIEW v_foo AS SELECT foo.*, foo_track_func(foo.*) FROM foo;

SELECT * FROM v_foo;
SELECT * FROM foo_track;

COMMIT;

Regards,

--
Fabrízio de Royes Mello
Consultoria/Coaching PostgreSQL
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