Mysql - 优化查询的帮助

Question

我有这个问题：

SELECT bi.id, 
       bi.location, 
       bi.expense_group, 
       bi.level, 
       bi.is_active, 
       bi.type, 
       full_name, 
       ( bl.bud_amount )                                     AS BudgetAmount, 
       ( COALESCE(( ( bl.bud_amount * 3 ) - ( 
                    + bal.bal_amount1 + bal.bal_amount2 
                    + bal.bal_amount3 ) ), 0) ) AS Difference, 
       ( COALESCE(Round(( + bal.bal_amount1 + bal.bal_amount2 
                          + bal.bal_amount3 ) / 3), 0) )     AS Average, 
       bal.bal_amount1                                       AS BAL1, 
       bal.bal_amount2                                       AS BAL2, 
       bal.bal_amount3                                       AS BAL3 
FROM   (SELECT * 
        FROM   budget_items bi 
        WHERE  bi.location IS NOT NULL) AS bi 
       LEFT JOIN (SELECT budget_item_id, 
                         Sum(CASE 
                               WHEN budget_id = 21491 THEN amount 
                             END) AS bud_amount 
                  FROM   budget_lines 
                  GROUP  BY budget_item_id) AS bl 
              ON bl.budget_item_id = bi.id 
       JOIN (SELECT budget_item_id, 
                    Ifnull(Sum(CASE 
                                 WHEN balance_id = 12841 THEN amount 
                               END), 0) AS bal_amount1, 
                    Ifnull(Sum(CASE 
                                 WHEN balance_id = 18647 THEN amount 
                               END), 0) AS bal_amount2, 
                    Ifnull(Sum(CASE 
                                 WHEN balance_id = 18674 THEN amount 
                               END), 0) AS bal_amount3 
             FROM   balance_lines 
             GROUP  BY budget_item_id) AS bal 
         ON bal.budget_item_id = bi.id 
ORDER  BY bi.location 

这需要很多时间。在budget_lines和balance_lines表中，每行有超过5,000,000行。

我还附加了查询的EXPLAIN，因此您将能够看到问题。 每个表中的所有ID都被编入索引。是否有任何列，如果将被索引加密查询？或许我需要改变它。

*** LEFT JOIN是必要的，因为我需要从nudget_items中获取所有项目，即使它们在balance / budget_line表中不存在。

架构是：每个预算都有其budget_lines。每个余额都有其balance_lines。该查询旨在使用一个表来总结预算和几个余额之间的差异。

您可以在此处看到更大的图片：http://i.stack.imgur.com/dlF8V.png

修改 在@Sebas回答之后：

对于@sabes饥饿，我在这里写了DESCRIBE： budget_items

budget_lines

balance_lines

Answer 1

也许是这样的;但没有样本数据和索引很难看到

SELECT * 
FROM   budget_items bi 
WHERE  bi.location IS NOT NULL) AS bi 
INNER JOIN  --Added inner for clarity  -changed order I just like my inner's before my outers.
  (SELECT budget_item_id, Sum(CASE WHEN balance_id = 12841 THEN coalesce(amount,0) END), 0) AS bal_amount1, 
                          Sum(CASE WHEN balance_id = 18647 THEN coalesce(amount,0) END), 0) AS bal_amount2, 
                          Sum(CASE WHEN balance_id = 18674 THEN coalesce(amount,0) END), 0) AS bal_amount3 
   FROM   balance_lines 
   WHERE balance_ID in (12841, 18647, 18674) --This way balance_IDs which aren't in this list don't even get evaluated
   GROUP  BY budget_item_id) AS bal 
 ON bal.budget_item_id = bi.id 
LEFT JOIN 
 (SELECT budget_item_id, Sum(CASE WHEN budget_id = 21491 THEN coalesce(amount,0) END) AS bud_amount 
  FROM   budget_lines 
  WHERE budget_Id = 21491 --Again since we only care about anything but budget_ID 21491, we can limit the results to JUST that 
  GROUP  BY budget_item_id) AS bl 
 ON bl.budget_item_id = bi.id