QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Unique (cost=32164.87..32164.89 rows=1 width=44) (actual time=221552.831..221552.831 rows=0 loops=1)
-> Sort (cost=32164.87..32164.87 rows=1 width=44) (actual time=221552.827..221552.827 rows=0 loops=1)
Sort Key: t.date_effective, t.acct_account_transaction_id, p.method, t.amount, c.business_name, t.amount
-> Nested Loop (cost=22871.67..32164.86 rows=1 width=44) (actual time=221552.808..221552.808 rows=0 loops=1)
-> Nested Loop (cost=22871.67..32160.37 rows=1 width=52) (actual time=221431.071..221546.619 rows=670 loops=1)
-> Nested Loop (cost=22871.67..32157.33 rows=1 width=43) (actual time=221421.218..221525.056 rows=2571 loops=1)
-> Hash Join (cost=22871.67..32152.80 rows=1 width=16) (actual time=221307.382..221491.019 rows=2593 loops=1)
Hash Cond: ("outer".acct_account_id = "inner".acct_account_fk)
-> Seq Scan on acct_account a (cost=0.00..7456.08 rows=365008 width=8) (actual time=0.032..118.369 rows=61295 loops=1)
-> Hash (cost=22871.67..22871.67 rows=1 width=16) (actual time=221286.733..221286.733 rows=2593 loops=1)
-> Nested Loop Left Join (cost=0.00..22871.67 rows=1 width=16) (actual time=1025.396..221266.357 rows=2593 loops=1)
Join Filter: ("inner".orig_acct_payment_fk = "outer".acct_account_transaction_id)
Filter: ("inner".link_type IS NULL)
-> Seq Scan on acct_account_transaction t (cost=0.00..18222.98 rows=1 width=16) (actual time=949.081..976.432 rows=2596 loops=1)
Filter: ((("type")::text = 'debit'::text) AND ((transaction_status)::text = 'active'::text) AND (date_effective >= '2012-03-01'::date) AND (date_effective < '2012-04-01 00:00:00'::timestamp without time zone))
-> Seq Scan on acct_payment_link l (cost=0.00..4648.68 rows=1 width=15) (actual time=1.073..84.610 rows=169 loops=2596)
Filter: ((link_type)::text ~~ 'return_%'::text)
-> Index Scan using contact_pk on contact c (cost=0.00..4.52 rows=1 width=27) (actual time=0.007..0.008 rows=1 loops=2593)
Index Cond: (c.contact_id = "outer".contact_fk)
-> Index Scan using acct_payment_transaction_fk on acct_payment p (cost=0.00..3.02 rows=1 width=13) (actual time=0.005..0.005 rows=0 loops=2571)
Index Cond: (p.acct_account_transaction_fk = "outer".acct_account_transaction_id)
Filter: ((method)::text <> 'trade'::text)
-> Index Scan using contact_role_pk on contact_role (cost=0.00..4.48 rows=1 width=4) (actual time=0.007..0.007 rows=0 loops=670)
Index Cond: ("outer".contact_id = contact_role.contact_fk)
Filter: (exchange_fk = 74)
Total runtime: 221553.019 ms
答案 0 :(得分：4)
你的问题在这里：
-> Nested Loop Left Join (cost=0.00..22871.67 rows=1 width=16) (actual time=1025.396..221266.357 rows=2593 loops=1)
Join Filter: ("inner".orig_acct_payment_fk = "outer".acct_account_transaction_id)
Filter: ("inner".link_type IS NULL)
-> Seq Scan on acct_account_transaction t (cost=0.00..18222.98 rows=1 width=16) (actual time=949.081..976.432 rows=2596 loops=1)
Filter: ((("type")::text = 'debit'::text) AND ((transaction_status)::text = 'active'::text) AND (date_effective >= '2012-03-01'::date) AND (date_effective
Seq Scan on acct_payment_link l (cost=0.00..4648.68 rows=1 width=15) (actual time=1.073..84.610 rows=169 loops=2596)
Filter: ((link_type)::text ~~ 'return_%'::text)
它希望在acct_account_transaction中找到1行，而它找到2596，对于另一个表也是如此。
你没有提到你的postgres版本（可以吗？），但这应该可以解决问题：
SELECT DISTINCT
t.date_effective,
t.acct_account_transaction_id,
p.method,
t.amount,
c.business_name,
t.amount
FROM
contact c inner join contact_role on (c.contact_id=contact_role.contact_fk and contact_role.exchange_fk=74),
acct_account a, acct_payment p,
acct_account_transaction t
WHERE
p.acct_account_transaction_fk=t.acct_account_transaction_id
and t.type = 'debit'
and transaction_status = 'active'
and p.method != 'trade'
and t.date_effective >= '2012-03-01'
and t.date_effective < (date '2012-03-01' + interval '1 month')
and c.contact_id=a.contact_fk and a.acct_account_id = t.acct_account_fk
and not exists(
select * from acct_payment_link l
where orig_acct_payment_fk == acct_account_transaction_id
and link_type like 'return_%'
)
ORDER BY
t.date_effective DESC
另外，尝试为相关列设置适当的统计目标。链接到友好手册：http://www.postgresql.org/docs/current/static/sql-altertable.html
答案 1 :(得分：0)
我删除了我的第一个建议，因为它改变了查询的性质。
我发现LEFT JOIN花了太多时间。
首先要尝试只对acct_payment_link表进行一次扫描。您可以尝试将查询重写为：
... LEFT JOIN (SELECT * FROM acct_payment_link
WHERE link_type LIKE 'return_%') AS l ...
您应该检查统计信息，因为计划行数和返回行数之间存在差异。
您没有包含表格和索引的定义，最好看一下这些。
您可能还希望使用contrib/pg_tgrm扩展程序在acct_payment_link.link_type上构建索引，但我会将此作为最后一个选项来尝试。
答案 2 :(得分：0)
你的索引是什么，你最近分析过吗？它正在acct_account_transaction上进行表扫描，即使该表上有多个条件：
如果这些列上没有索引，那么复合一个(type, date_effective)可以提供帮助（假设有很多行不符合这些列的标准）。
答案 3 :(得分：0)
您的陈述被重写并格式化：
SELECT DISTINCT
t.date_effective,
t.acct_account_transaction_id,
p.method,
t.amount,
c.business_name,
t.amount
FROM contact c
JOIN contact_role cr ON cr.contact_fk = c.contact_id
JOIN acct_account a ON a.contact_fk = c.contact_id
JOIN acct_account_transaction t ON t.acct_account_fk = a.acct_account_id
JOIN acct_payment p ON p.acct_account_transaction_fk
= t.acct_account_transaction_id
LEFT JOIN acct_payment_link l ON orig_acct_payment_fk
= acct_account_transaction_id
-- missing table-qualification!
AND link_type like 'return_%'
-- missing table-qualification!
WHERE transaction_status = 'active' -- missing table-qualification!
AND cr.exchange_fk = 74
AND t.type = 'debit'
AND t.date_effective >= '2012-03-01'
AND t.date_effective < (date '2012-03-01' + interval '1 month')
AND p.method != 'trade'
AND l.link_type IS NULL
ORDER BY t.date_effective DESC;
最好使用显式JOIN语句。我根据您的JOIN逻辑重新排序了表格。
为什么(date '2012-03-01' + interval '1 month')代替日期'2012-04-01'？
缺少某些表格资格。在这样一个复杂的陈述中，这是一种糟糕的风格。可能隐瞒了一个错误。
性能的关键是索引，适当的，适当的配置的PostgreSQL和准确的统计。
General advice on performance tuning in the PostgreSQL wiki.