SQL查询优化-执行时间

Question

我正在执行以下查询，这花了我2秒钟的时间来执行，现在大约需要10分钟，因为我在表custom_redemptions中增加了100个条目，而在其他表中又增加了大约10个条目。

随着DISTINCT它使我返回

Showing rows 0 - 29 (96 total, Query took 0.00156 sec)

我拿出DISTINCT跟踪该错误，它返回了我

 Showing rows 0 - 29 (94174080 total, Query took 0.1510 sec)

有什么办法可以优化这个？

SELECT DISTINCT c.id, c.couponid, c.branchid, c.chainid
FROM `users_roles` a,
     `field_data_field_ypefthinos` b,
     `custom_redemptions` c,
     `field_data_field_chain_manager` e,
     `field_data_field_node_tax_inception` f,
     `field_data_field_brand_manager` j,
     `field_data_field_brand_node_ref` k,
     `field_data_field_product_ref` i,
     `field_data_field_company_manager` z,
     `field_data_field_brand_company` t
WHERE (a.rid = 4
       AND a.uid = 351
       AND b.field_ypefthinos_uid = a.uid
       AND b.entity_id = c.branchid)
   OR
      (a.rid = 5
       AND a.uid = 351
       AND e.field_chain_manager_uid = a.uid
       AND e.entity_id = f.entity_id
       AND f.field_node_tax_inception_tid = c.chainid)
   OR
      (a.rid = 9
       AND a.uid = 351
       AND j.field_brand_manager_uid = a.uid
       AND j.entity_id = k.field_brand_node_ref_nid
       AND k.entity_id = i.field_product_ref_nid
       AND i.entity_id = c.couponid)
   OR
      (a.rid = 6
       AND a.uid = 351
       AND z.field_company_manager_uid = a.uid
       AND z.entity_id = t.field_brand_company_nid
       AND t.entity_id = k.field_brand_node_ref_nid
       AND k.entity_id = i.field_product_ref_nid
       AND i.entity_id = c.couponid)

Answer 1

步骤1.您具有4个条件的OR 。 将查询转换为4个SELECTs的UNION ，每个选择都具有OR条件之一。

步骤2.删除每个SELECT未使用的表（摆脱笛卡尔乘积）。

第3步：添加INDEX(uid, rid)以任何顺序）到a 。