I want to implement history of changes of PostgreSQL table. The table is defined the following way:
CREATE TABLE "ps_counters"
(
"psid" integer NOT NULL,
"counter" bigint[] NOT NULL
);
I want the history table to look like:
CREATE TABLE "ps_counters_history"
(
"timestamp" timestamp NOT NULL,
"psid" integer NOT NULL,
"counter" bigint[] NOT NULL
);
I need a trigger and a stored procedure which on every change (insertion or update) in ps_couneters
to insert in ps_counters_history
, but in addition to prevent ps_counters_history
to became too big I want partitioning of ps_counters_history
table on every month.
I managed to implement it.
CREATE TABLE "ps_counters_history"
(
"id" serial PRIMARY KEY,
"timestamp" timestamp NOT NULL DEFAULT clock_timestamp(),
"psid" integer NOT NULL,
"counter" bigint[] NOT NULL
);
CREATE OR REPLACE FUNCTION ps_counters_history_trigger()
RETURNS trigger AS
$BODY$
DECLARE
table_name text;
BEGIN
table_name := 'ps_counters_history_' || to_char(CURRENT_DATE, 'yyyy_mm');
IF NOT EXISTS (SELECT 1 FROM pg_class WHERE relname = table_name)
THEN
EXECUTE 'CREATE TABLE IF NOT EXISTS ' || table_name ||
' () INHERITS (ps_counters_history);';
END IF;
EXECUTE 'INSERT INTO ' || table_name ||
'(psid, counter) VALUES ($1.psid, $1.counter);' USING NEW;
RETURN NEW;
END
$BODY$
LANGUAGE plpgsql;
CREATE TRIGGER ps_counters_history_trigger
AFTER INSERT OR UPDATE ON ps_counters FOR EACH ROW
EXECUTE PROCEDURE ps_counters_history_trigger();
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