Re: triple self-join crawling

T E Schmitz wrote:
> T E Schmitz wrote:
>
> Things improved hugely when I changed the JOIN clauses:

see explain analyze below - can this be improved further?

>
> LEFT OUTER JOIN history AS past_month ON (past_month.stock =
> history.stock AND past_month.day >= (history.day - 30) AND
> past_month.day < history.day)
> LEFT OUTER JOIN history AS past_week ON (past_week.stock =
> past_month.stock AND past_week.day =past_month.day AND past_week.day >=
> (history.day - 7))

QUERY PLAN
GroupAggregate (cost=1370368.19..1435888.88 rows=5801 width=56) (actual
time=11945.030..13163.156 rows=5801 loops=1)
-> Sort (cost=1370368.19..1379715.86 rows=3739067 width=56) (actual
time=11944.753..12462.623 rows=120117 loops=1)
Sort Key: history.stock, history."day", history.high, history.low
-> Hash Left Join (cost=160.02..391554.63 rows=3739067
width=56) (actual time=52.746..3778.409 rows=120117 loops=1)
Hash Cond: ((("outer".stock)::text =
("inner".stock)::text) AND ("outer"."day" = "inner"."day"))
Join Filter: ("inner"."day" >= ("outer"."day" - 7))
-> Nested Loop Left Join (cost=0.00..204441.26
rows=3739067 width=57) (actual time=0.077..2313.375 rows=120117 loops=1)
Join Filter: (("inner".stock)::text =
("outer".stock)::text)
-> Seq Scan on history (cost=0.00..131.01
rows=5801 width=34) (actual time=0.016..34.845 rows=5801 loops=1)
-> Index Scan using idx_history_day on history
past_month (cost=0.00..22.32 rows=645 width=23) (actual
time=0.020..0.185 rows=21 loops=5801)
Index Cond: ((past_month."day" >=
("outer"."day" - 30)) AND (past_month."day" < "outer"."day"))
-> Hash (cost=131.01..131.01 rows=5801 width=23)
(actual time=52.608..52.608 rows=5801 loops=1)
-> Seq Scan on history past_week
(cost=0.00..131.01 rows=5801 width=23) (actual time=0.010..25.110
rows=5801 loops=1)

Total runtime: 13187.729 ms
--

Regards,

Tarlika Elisabeth Schmitz