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copied!<p>It looks like in PostgreSQL constraint exclusion on booleans does not work. When you use <code>integer</code> or <code>enum</code> then it works well.</p> <p>Integer:</p> <pre><code>CREATE TABLE mos (type_id INTEGER UNIQUE, expired int); CREATE TABLE mos_expired_1 ( CHECK ( expired = 0 ) ) INHERITS (mos); CREATE TABLE mos_active_1 ( CHECK ( expired = 1 ) ) INHERITS (mos); INSERT INTO mos_expired_1 (type_id,expired) VALUES(1, 0); INSERT INTO mos_active_1 (type_id,expired) VALUES(2, 1); analyze; EXPLAIN SELECT * from mos where expired = 0; QUERY PLAN ----------------------------------------------------------------------------- Result (cost=0.00..37.76 rows=12 width=8) -> Append (cost=0.00..37.76 rows=12 width=8) -> Seq Scan on mos (cost=0.00..36.75 rows=11 width=8) Filter: (expired = 0) -> Seq Scan on mos_expired_1 mos (cost=0.00..1.01 rows=1 width=8) Filter: (expired = 0) (6 rows) EXPLAIN SELECT * from mos where expired = 1; QUERY PLAN ---------------------------------------------------------------------------- Result (cost=0.00..37.76 rows=12 width=8) -> Append (cost=0.00..37.76 rows=12 width=8) -> Seq Scan on mos (cost=0.00..36.75 rows=11 width=8) Filter: (expired = 1) -> Seq Scan on mos_active_1 mos (cost=0.00..1.01 rows=1 width=8) Filter: (expired = 1) (6 rows) </code></pre> <p>Enum:</p> <pre><code>CREATE TYPE mybool AS ENUM ('true', 'false'); CREATE TABLE mos (type_id INTEGER UNIQUE, expired mybool); CREATE TABLE mos_expired_1 ( CHECK ( expired = 'true' ) ) INHERITS (mos); CREATE TABLE mos_active_1 ( CHECK ( expired = 'false' ) ) INHERITS (mos); INSERT INTO mos_expired_1 (type_id,expired) VALUES(1, 'true'); INSERT INTO mos_active_1 (type_id,expired) VALUES(2, 'false'); analyze; EXPLAIN SELECT * from mos where expired = 'true'; QUERY PLAN ----------------------------------------------------------------------------- Result (cost=0.00..37.76 rows=12 width=8) -> Append (cost=0.00..37.76 rows=12 width=8) -> Seq Scan on mos (cost=0.00..36.75 rows=11 width=8) Filter: (expired = 'true'::mybool) -> Seq Scan on mos_expired_1 mos (cost=0.00..1.01 rows=1 width=8) Filter: (expired = 'true'::mybool) (6 rows) EXPLAIN SELECT * from mos where expired = 'false'; QUERY PLAN ---------------------------------------------------------------------------- Result (cost=0.00..37.76 rows=12 width=8) -> Append (cost=0.00..37.76 rows=12 width=8) -> Seq Scan on mos (cost=0.00..36.75 rows=11 width=8) Filter: (expired = 'false'::mybool) -> Seq Scan on mos_active_1 mos (cost=0.00..1.01 rows=1 width=8) Filter: (expired = 'false'::mybool) (6 rows) </code></pre> <p>I don't know if it is a bug. I think it is not documented anywhere.</p>

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