Hi
Following up the performance problems I am having in migrating an
application to Postgres I have noticed that one query gives me
ncndb=# explain select code from tableA where code=9;
QUERY PLAN
----------------------------------------------------------------
Seq Scan on tableA (cost=0.00..18451.99 rows=2 width=8)
Filter: (code = 9)
(2 rows)
whilst another provides
ncndb=# explain select code from tableB where code=123;
QUERY PLAN
----------------------------------------------------------------------------
Index Scan using contacts_pk on contacts (cost=0.00..3.71 rows=1
width=4)
Index Cond: (code = 123)
(2 rows)
The two table are a similar size, and have a field, code, as their
primary key. In tableA, code is a bigint, whilst in tableB is an
integer.
Is there a reason why the table with the bigint code column does full
table scans (cost 18500), whilst the other uses an index scan (cost
3.7).
Many thanks
Simon
--
Simon Windsor
Email: simon.windsor@cornfield.org.uk
Tel: 01454 617689
Mob: 07960 321599
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