On Mon, Jul 24, 2017 at 3:22 PM, Dmitry Lazurkin <dila...@gmail.com> wrote:
> ALTER TABLE ids ALTER COLUMN id SET NOT NULL; > EXPLAIN (ANALYZE, BUFFERS) SELECT count(*) FROM ids WHERE id IN > :values_clause; > > Aggregate (cost=245006.46..245006.47 rows=1 width=8) (actual > time=3824.095..3824.095 rows=1 loops=1) > Buffers: shared hit=44248 > -> Hash Join (cost=7.50..235006.42 rows=4000019 width=0) (actual > time=1.108..3327.112 rows=3998646 loops=1) > ... > You haven't constrained the outer relation (i.e., :values_clause) to be non-null which is what I believe is required for the semi-join algorithm to be considered. David J.