> Table a has 15905 rows and table b has 25905 rows.
>
>
> For the following query
>
> select a.pkey, b.key2 from a, b
> where b.key1 = 1369
> and a.pkey = b.key1;
>
> "explain" shows
>
> NOTICE: QUERY PLAN:
>
> Nested Loop (cost=6.19 rows=3 width=10)
> -> Index Scan using b_pkey on b on b (cost=2.09 rows=2 width=6)
> -> Index Scan using a_pkey on a on a (cost=2.05 rows=15905 width=4)
>
> What does "rows=15905" of InnerPlan mean ?
> Is "rows=3" of Nested Loop irrelevant to "rows=15905" ?
It means it thinks it is going to access X rows in that pass, but end
up with 3 joined rows as a result of the nested loop. It is only an
estimate, based on table size and column uniqueness from vacuum analyze.
-- Bruce Momjian | http://www.op.net/~candle maillist@candle.pha.pa.us | (610)
853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill,
Pennsylvania19026
