This is a bad idea. You're creating a MATERIALIZED VIEW
, just use the native functionality for that.
CREATE MATERIALIZED VIEW schema_test
AS SELECT timestamp, component_name, component_type, status, message;
Then simply run REFRESH MATERIALIZED VIEW
schema_test;
it will clear out the old results and insert the new results of the query.
The manual for psql:
Variable interpolation will not be performed within quoted SQL literals and identifiers.
The body of a DO
statement (or function) is a quoted literal. Dollar-quoted in this case, but all the same:
$$
DECLARE
_now_date timestamp := :now_utc;
BEGIN
--
END
$$
To enable SQL interpolation, do it outside the string and then concatenate - which gets tedious quickly ...
One way to make it simpler is to let Postgres do the string processing and then execute the result using \gexec
. Call from psql:
SELECT format($$
DO
$do$
DECLARE
_now_date timestamp := %L;
BEGIN
RAISE NOTICE '%%', _now_date;
END
$do$;
$$, :'now_utc')\gexec
NOTICE: 2019-06-14 00:41:53.040879
DO
(%
has a special meaning inside format()
, using %%
to get a single %
in the string.)
Also note the syntax :'now_utc'
to get a quoted string.
To just use the current UTC timestamp, you don't need all this complication:
DO
$do$
DECLARE
_now_date timestamp := now() AT TIME ZONE 'UTC';
BEGIN
RAISE NOTICE '%', _now_date;
END
$do$;
DO
statements are not meant to take parameters. It's simpler to create a (temporary) function and pass value(s) as function parameter(s) in the call:
CREATE FUNCTION pg_temp.foo(_now_date timestamp)
RETURNS void AS
$func$
BEGIN
RAISE NOTICE '%', _now_date;
END
$func$ LANGUAGE plpgsql;
Call with SQL interpolation in psql:
SELECT pg_temp.foo(:'now_utc');
Finally, for passing values, you can also (ab)use a Postgres "customized option" (as session variable):
SET myvars.now_date TO :'now_utc';
DO
$do$
BEGIN
RAISE NOTICE '%', current_setting('myvars.now_date', true);
END
$do$;
Note that the the value is stored as text
and you may need to cast.
Details:
But then you might skip the psql variable and set the option in Postgres directly ...
Best Answer
As said in "40.5.3. Executing a Query with a Single-row Result" (emphasis mine):
So this should work: