Re: Oddball data distribution giving me planner headaches

--- On Fri, 12/2/11, David Johnston <polobo@yahoo.com> wrote:

> From: David Johnston <polobo@yahoo.com>
> What kind of plan does the following give?
>
> EXPLAIN ANALYZE
> SELECT *
> FROM customer_rel p
> JOIN customer c ON (p.parent_customer = c.customer_id)
> WHERE c.customer_type = 'DISTRIBUTOR'

Nearly identical output

"Nested Loop  (cost=0.00..29624.69 rows=931 width=97) (actual time=0.032..1330.208 rows=1025401 loops=1)"
"  ->  Seq Scan on customer c  (cost=0.00..25429.10 rows=136 width=71) (actual time=0.017..212.059 rows=68 loops=1)"
"        Filter: (customer_type = 'DISTRIBUTOR'::bpchar)"
"  ->  Index Scan using rel_parent on customer_rel p  (cost=0.00..30.76 rows=7 width=26) (actual time=0.006..7.732
rows=15079loops=68)" 
"        Index Cond: (parent_customer = c.customer_id)"
"Total runtime: 1544.281 ms"