Oracle SQL 查询运行缓慢

Question

我在下面有一个用于搜索功能的 oracle SQL 查询，它包含在存储过程中。

它运行得很慢。

打开 p_cursor FOR 选择 表A.*, TB_S.someColumn, TB_S.SomeColumn ..

    FROM
        customer_site TableA
        LEFT JOIN TableB TB on TB.some_id = TableA.some_id
        LEFT JOIN TableC TB_S on TB_S.Bla_ID = TB.Bla_ID
        LEFT JOIN TableC TB_CS on TB_CS.Bla2_ID = TB.Bla2_ID
        LEFT JOIN TableC TB_1 on TB_1.Bla3_ID = TB.Bla3_ID
        LEFT JOIN TableC TB_2 on TB_DC.Bla4_ID = TB.Bla4_ID
        LEFT JOIN TableD SP on SP.SP_ID = TableA.SP_ID
        LEFT JOIN TableC TB_3 on TB_3.Bla5_ID = TB.Bla5_ID
        LEFT JOIN TableC TB_4 on TB_4.Bla6_ID = TB.Bla6_ID
        LEFT JOIN TableC TB_5 on TB_5.Bla7_ID = TB.Bla7_ID
    WHERE 
        (p_nmi IS NULL OR TableA.someid LIKE p_nmi)
        AND (p_last_name IS NULL OR TableA.last_name LIKE p_last_name)
        AND (p_full_address IS NULL OR
            UPPER(assemble_address(flat_number, street_number, street_name,
                street_suffix, apartment_number, building_name, suburb, state, postcode))
            LIKE p_full_address)
        AND (p_param1 IS NULL OR TB.owner = p_param1)
        AND (p_param2 IS NULL OR TB.status = p_param2)
        AND (p_param3 IS NULL OR TB.contact_stage = p_param3)
        AND (p_param4 IS NULL OR TB.no_access_code = p_param4)
        AND (p_param5 IS NULL OR TB.defect_code = p_param5)
        AND (p_param6 IS NULL OR TB.REFUSAL_RESOLUTION = p_param6)
        AND (p_param7 IS NULL OR TB.DEFECT_LEVEL = p_param7)
        AND (p_param8 IS NULL OR TB.AMI_CTR_STATUS = p_param8)
        AND (p_param9 IS NULL OR TableA.meter_route LIKE p_param9)
        AND (p_param10 IS NULL OR TableA.sp_id = p_param10)
        AND (p_inTBdent_date_from IS NULL OR TB.inTBdent_date >= p_inTBdent_date_from)
        AND (p_inTBdent_date_to IS NULL OR TB.inTBdent_date <= p_inTBdent_date_to)
        AND rownum < 1001
    ORDER BY
        TB.inTBdent_date;

数据库专家可以帮助我如何调整上述查询吗？

谢谢。

Answer 1

按照@Annjawn 的建议，将(p_param IS NULL or col = p_param) 的所有实例更改为col = nvl(p_param, col)。如this Jonathan Lewis article 所述，Oracle 可以优化这些条件。这可能会启用INDEX RANGE SCAN 而不是TABLE ACCESS FULL。但是，只有当列为 NOT NULL 时，该更改在逻辑上才等效，因为 null = null 不会返回 true。 （我个人更喜欢您编写条件的方式，但 Oracle 似乎讨厌 OR。）

如果这没有帮助，请发布解释计划以确定真正的问题。首先，修改程序，添加提示SELECT /*+ gather_plan_statistics */ TableA.*, ...。运行该过程，然后使用类似select * from v$sql where lower(sql_fulltext) like '%gather_plan_statistics%'; 的查询找到相关的SQL_ID。最后贴出结果 select * from table(dbms_xplan.display_cursor(sql_id => '<sql_id from previous step>', format => 'allstats last'));。这将告诉我们执行计划以及优化器做出的错误决策。