Daniel Kalchev <daniel@digsys.bg> writes:
> (table has ~30k rows)
> EXPLAIN SELECT * FROM r where d = 8;
> The result is
> NOTICE: QUERY PLAN:
> Seq Scan on r (cost=0.00...3041.13 rows=7191 width=4)
Seqscan is the right plan to retrieve 7k rows out of a 30k table.
So the question is whether that estimate is in the right ballpark
or not. How many rows are there really with d=8? If it's way off,
what do you get from
select attname,attdispersion,s.*
from pg_statistic s, pg_attribute a, pg_class c
where starelid = c.oid and attrelid = c.oid and staattnum = attnum
and relname = 'r';
regards, tom lane
