CREATE OR REPLACE FUNCTION now_function_ts_notz() RETURNS timestamp without time zone AS $BODY$ SELECT (NOW())::timestamp without time zone; $BODY$ LANGUAGE sql IMMUTABLE STRICT COST 100;
2.
CREATE VIEW v_recent_food AS SELECT * FROM food WHERE food.post_timestamp >= (now_function_ts_notz() - '1 mon'::interval)::date AND food.post_timestamp <= now_function_ts_notz()::timestamp without time zone ORDER BY food.post_timestamp DESC LIMIT 30;
While running 'EXPLAIN ANALYZE select * from v_recent_items'
I found that it skipped the partition table food_2013p.
Is it a valid work around? Or there is other better or elegant way?
Thanks and regards,
Patrick
On Thursday, August 21, 2014 4:01 PM, Patrick Dung <patrick_dkt@yahoo.com.hk> wrote:
CREATE OR REPLACE FUNCTION now_function_ts_notz() RETURNS timestamp without time zone AS $BODY$ SELECT (NOW())::timestamp without time zone; $BODY$ LANGUAGE sql IMMUTABLE STRICT COST 100;
2. Create my View like this:
CREATE OR REPLACE VIEW v_recent_items AS SELECT * FROM food WHERE food.post_timestamp >= (now_function_ts_notz() - '1 mon'::interval)::timestamp without time zone AND food.post_timestamp <= now()::timestamp without time zone ORDER BY food.post_timestamp DESC LIMIT 30;
While running 'EXPLAIN ANALYZE select * from v_recent_items'
I found that it skipped the partition table food_2013p.
Is it a valid work around? Or there is other better or elegant way?
Thanks and regards,
Patrick
On Thursday, August 21, 2014 3:21 PM, Patrick Dung <patrick_dkt@yahoo.com.hk> wrote:
Resent. As I could not see my mail in the mailing list after about two hours.
On Thursday, August 21, 2014 1:43 PM, Patrick Dung <patrick_dkt@yahoo.com.hk> wrote:
Hi Postgresql users,
I have a master table with two partition table (food_2013p, food_2014p).
I found that when I use SELECT + 'now' constant, constraint exclusion works, (it skipped the 2013 partition).
EXPLAIN ANALYZE SELECT * FROM food WHERE food.post_timestamp >= ('now'::date - interval '1 month')::date AND food.post_timestamp <= 'now' ORDER BY food.post_timestamp DESC LIMIT 30;
But when I put the query inside view, 'now' is converted to the timestamp when I run the create view.
So the view becomes:
WHERE food.post_timestamp >= ('2014-08-21'::date - '1 mon'::interval)::date AND food.post_timestamp <= '2014-08-21 13:38:29.642347'::timestamp without time zone
This is not dynamic.
When I use now(), the query will scan other partition tables. I know this is a restriction of partition on non-immutable function.
Would it be possible or a feature request to take advantage of the partition table with query like this?
