Gregory Stark <stark@enterprisedb.com> writes:
> "Tom Lane" <tgl@sss.pgh.pa.us> writes:
>> I already demonstrated that we could.
> We seem to be talking past each other. The plan you showed is analogous but
> using a plain old index scan.
That's only because that seemed like the appropriate thing for the given
case's statistics. [ fiddles with example... ]
regression=# explain select * from tenk1 a where thousand in (select f1 from int4_tbl b);
QUERY PLAN
------------------------------------------------------------------------------------------Nested Loop
(cost=5.39..198.81rows=51 width=244) -> HashAggregate (cost=1.06..1.11 rows=5 width=4) -> Seq Scan on
int4_tblb (cost=0.00..1.05 rows=5 width=4) -> Bitmap Heap Scan on tenk1 a (cost=4.33..39.41 rows=10 width=244)
Recheck Cond: (a.thousand = b.f1) -> Bitmap Index Scan on tenk1_thous_tenthous (cost=0.00..4.33 rows=10
width=0) Index Cond: (a.thousand = b.f1)
(7 rows)
regards, tom lane