Hi,

looking at merge tables and the related query plans I was expecting the planner to skip tables depending on partition information and query predicates.

I'm using the official example for merge tables: https://www.monetdb.org/blog/updatable-merge-tables

CREATE MERGE TABLE splitted (stamp TIMESTAMP, val INT) PARTITION BY RANGE ON (stamp);
CREATE TABLE first_decade (stamp TIMESTAMP, val INT);
CREATE TABLE second_decade (stamp TIMESTAMP, val INT);
CREATE TABLE third_decade (stamp TIMESTAMP, val INT);
ALTER TABLE splitted ADD TABLE first_decade AS PARTITION FROM TIMESTAMP '2000-01-01 00:00:00' TO TIMESTAMP '2010-01-01 00:00:00';
ALTER TABLE splitted ADD TABLE second_decade AS PARTITION FROM TIMESTAMP '2010-01-01 00:00:00' TO TIMESTAMP '2020-01-01 00:00:00';
ALTER TABLE splitted ADD TABLE third_decade AS PARTITION FROM TIMESTAMP '2020-01-01 00:00:00' TO RANGE MAXVALUE WITH NULL VALUES;
INSERT INTO splitted VALUES (TIMESTAMP '2000-01-01 00:00:00', 1), (TIMESTAMP '2002-12-03 20:00:00', 2), (TIMESTAMP '2012-05-12 21:01:00', 3), (TIMESTAMP '2019-12-12 23:59:59', 4);
INSERT INTO splitted VALUES (TIMESTAMP '2020-01-01 00:00:00', 5), (NULL, 6);

When I trigger the following query I was expecting that only table second_decade would be used as Monet would be smart enough to check the partition information for each table.

Kind regards,
Daniel

sql>plan select * from splitted where stamp = TIMESTAMP '2020-01-01 00:00:00';
+--------------------------------------------------------------------------------------------------------------------------------------+
| rel |
+======================================================================================================================================+
| union ( |
| | union ( |
| | | project ( |
| | | | select ( |
| | | | | table(sys.first_decade) [ "first_decade"."stamp" as "splitted"."stamp", "first_decade"."val" as "splitted"."val" ] COUNT |
| | | | ) [ "splitted"."stamp" = timestamp(7) "2020-01-01 00:00:00.000000" ] |
| | | ) [ "splitted"."stamp", "splitted"."val" ], |
| | | project ( |
| | | | select ( |
| | | | | table(sys.second_decade) [ "second_decade"."stamp" as "splitted"."stamp", "second_decade"."val" as "splitted"."val" ] COUNT |
| | | | ) [ "splitted"."stamp" = timestamp(7) "2020-01-01 00:00:00.000000" ] |
| | | ) [ "splitted"."stamp", "splitted"."val" ] |
| | ) [ "splitted"."stamp", "splitted"."val" ], |
| | project ( |
| | | select ( |
| | | | table(sys.third_decade) [ "third_decade"."stamp" as "splitted"."stamp", "third_decade"."val" as "splitted"."val" ] COUNT |
| | | ) [ "splitted"."stamp" = timestamp(7) "2020-01-01 00:00:00.000000" ] |
| | ) [ "splitted"."stamp", "splitted"."val" ] |
| ) [ "splitted"."stamp", "splitted"."val" ] |
+--------------------------------------------------------------------------------------------------------------------------------------+
19 tuples
clk: 2.428 ms