From: Bruce Momjian <bruce@momjian.us>
To: Simon Riggs <simon@2ndquadrant.com>
Cc: PostgreSQL-documentation <pgsql-docs@postgresql.org>
Subject: Partitioning documentation example
Date: Fri, 4 Jan 2008 10:27:07 -0500 (EST)
Message-ID: <200801041527.m04FR7L19863@momjian.us> (raw)
Simon, I was looking at the new table partitioning documentation that
recommends triggers:
http://developer.postgresql.org/pgdocs/postgres/ddl-partitioning.html#DDL-PARTITIONING-IMPLEMENTATIO...
and came upon this trigger function example:
CREATE OR REPLACE FUNCTION measurement_insert_trigger()
RETURNS TRIGGER AS $$
BEGIN
IF ( NEW.logdate >= DATE '2006-02-01' AND NEW.logdate < DATE '2006-03-01' ) THEN
INSERT INTO measurement_y2006m02 VALUES (NEW.*);
ELSIF ( NEW.logdate >= DATE '2006-03-01' AND NEW.logdate < DATE '2006-04-01' ) THEN
INSERT INTO measurement_y2006m03 VALUES (NEW.*);
...
ELSIF ( NEW.logdate >= DATE '2008-01-01' AND NEW.logdate < DATE '2008-02-01' ) THEN
INSERT INTO measurement_y2008m01 VALUES (NEW.*);
ELSE
RAISE EXCEPTION 'Date out of range. Fix the measurement_insert_trigger() function!';
END IF;
RETURN NULL;
END;
$$
LANGUAGE plpgsql;
It seems to me it would be much clearer if we added a second example
that used to_char() to create the INSERT statement dynamically based on
NEW.logdate:
CREATE OR REPLACE FUNCTION measurement_insert_trigger()
RETURNS TRIGGER AS $$
BEGIN
EXECUTE 'INSERT INTO measurement_y' || to_char(NEW.logdate,'YYYY_mMM') || ' VALUES (NEW.*)';
END;
$$
LANGUAGE plpgsql;
It will of course fail if the table does not exist, which I think is
what we want. This trigger function would not have to be modified when
new tables are added.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://postgres.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
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To: pgsql-docs@postgresql.org
Cc: bruce@momjian.us, simon@2ndquadrant.com
Subject: Re: Partitioning documentation example
In-Reply-To: <200801041527.m04FR7L19863@momjian.us>
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