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Re: Emulating trigger BEFORE SELECT behavior - Mailing list pgsql-general

From Fabrízio de Royes Mello
Subject Re: Emulating trigger BEFORE SELECT behavior
Date
Msg-id CAFcNs+rrRxsO1W5N7UN_p5MJreh7n61gLm1UqAREEm8D534o3Q@mail.gmail.com
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In response to Re: Emulating trigger BEFORE SELECT behavior  (Atri Sharma <atri.jiit@gmail.com>)
Responses Re: Emulating trigger BEFORE SELECT behavior
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On Thu, Apr 18, 2013 at 11:02 AM, Atri Sharma <atri.jiit@gmail.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
>> Blog sobre TI: http://fabriziomello.blogspot.com
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