Hi testdb3=# \d csischema.dim_company; Table "csischema.dim_company" Column | Type | Modifiers -----------------+-----------------------------+----------- company_id | integer | not null company_name | character varying(100) | city | character varying(100) | state | character varying(100) | postal_code | character varying(100) | country | character varying(100) | latitude | double precision | longitude | double precision | update_datetime | timestamp without time zone | company_source | character varying(1) | Indexes: "dim_company_pkey" PRIMARY KEY, btree (company_id) testdb3=# \d woc.dim_company; Table "woc.dim_company" Column | Type | Modifiers -----------------+-----------------------------+----------- company_id | integer | not null company_name | character varying(100) | city | character varying(100) | state | character varying(100) | postal_code | character varying(100) | country | character varying(100) | latitude | double precision | longitude | double precision | update_datetime | timestamp without time zone | company_source | character varying(1) | Indexes: "dim_company_pkey" PRIMARY KEY, btree (company_id) testdb3=# select count(*) from csischema.dim_company; count --------- 1786376 (1 row) testdb3=# select count(*) from woc.dim_company; count ------- 18980 (1 row) woc.dim_company is a subset of csischema.dim_company meaning all company_id from woc.dim_company are in csischema.dim_company Ratio is around 1% SELECT a.company_id FROM csischema.dim_company a, woc.dim_company b WHERE a.company_id = b.company_id; testdb3=# explain analyze SELECT a.company_id FROM csischema.dim_company a, woc.dim_company b testdb3-# WHERE a.company_id = b.company_id; QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------- Hash Join (cost=711.05..54938.35 rows=18980 width=4) (actual time=34.067..1118.603 rows=18980 loops=1) Hash Cond: (a.company_id = b.company_id) -> Seq Scan on dim_company a (cost=0.00..47097.82 rows=1850582 width=4) (actual time=0.013..523.249 rows=1786376 loops=1) -> Hash (cost=473.80..473.80 rows=18980 width=4) (actual time=20.203..20.203 rows=18980 loops=1) Buckets: 32768 Batches: 1 Memory Usage: 924kB -> Seq Scan on dim_company b (cost=0.00..473.80 rows=18980 width=4) (actual time=0.007..10.076 rows=18980 loops=1) Planning time: 0.511 ms Execution time: 1121.068 ms (8 rows) I was expecting at least the PK of csischema.dim_company to be used . In another DBMS that was the case. The larger table , csischema.dim_company used the PK. Any hints, thoughts what am I not seing ? Thank you Armand -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general