MySQL篇-SQL优化实战-减少子查询

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上一篇了解了分析SQL使用的explain，可以点击查看MySQL篇-SQL优化实战了解我在写sql的注意事项还有explain的说明，这次拿一段生产使用的sql进行优化说明。从14s优化到2.6s

待优化的SQL

sql 复制代码

SELECT DISTINCT
	swpe.tag_number,
	hca.ACCOUNT_NAME customer_name,
	sipa.PIN_LOGO area_number,
	cdla.delivery_header_id,
	swpe.pack_number,
	swph.packslip_number,
	cdpa.transport_mode,
	date_format(
	    swpe.inware_date,
	    '%Y-%m-%d %H:%i:%s'
	) in_warehouse_date,
	DATE(cdla.act_delivery_date) act_delivery_date,
	cdla.plate_number,
    wbp.PLATFORM_NAME schedule_stage_mir,
    sooh.order_number,
    swph.lot_number,
    milk.ATTRIBUTE14,
    ifnull(
        (
            SELECT
                'Y'
            FROM
                cwms_delivery_attachment_all cda
            WHERE
                cda.pack_entity_id = swpe.pack_entity_id
            AND cda.stock_scan_status = 'Y'
            LIMIT 1
        ),
        'N'
    ) stock_status,
    ifnull(
        (
            SELECT
                cda.comments
            FROM
                cwms_delivery_attachment_all cda
            WHERE
                cda.pack_entity_id = swpe.pack_entity_id
            LIMIT 1
        ),
        NULL
    ) comments,
	 ifnull(
	    (
	        SELECT
	            swdh.delivery_number
	        FROM
	            sfy_wsh_delivery_lines_all swdl
	        INNER JOIN sfy_wsh_delivery_headers_all swdh ON swdl.delivery_header_id = swdh.delivery_header_id
	        WHERE
	            swpe.tag_number = swdl.tag_number
	        LIMIT 1
	    ),
	    NULL
	) delivery_number,
	 ifnull(
	    (
	        SELECT
	            filter1
	        FROM
	            eos_dict_entry
	        WHERE
	            DICTTYPEID = 'AUTH_CONFIG'
	        LIMIT 1
	    ),
	    'Y'
	) zc_power,
	 ppl.PICK_NUMBER pd_number,
	
	IF (
	    ifnull(
	        (
	            SELECT
	
	            IF (
	                substr(father.license_number, 1, 2) = 'TP',
	                father.license_number,
	                NULL
	            ) tp_number
	            FROM
	                wms_mtl_onhand_quantities_detail child
	            INNER JOIN wms_mtl_onhand_quantities_detail father ON child.parent_mq_id = father.mq_id
	            WHERE
	                child.license_number = swpe.tag_number
	            LIMIT 1
	        ),
	        1
	    ) != 1,
	    (
	        SELECT
	
	        IF (
	            substr(father.license_number, 1, 2) = 'TP',
	            father.license_number,
	            NULL
	        ) tp_number
	        FROM
	            wms_mtl_onhand_quantities_detail child
	        INNER JOIN wms_mtl_onhand_quantities_detail father ON child.parent_mq_id = father.mq_id
	        WHERE
	            child.license_number = swpe.tag_number
	        LIMIT 1
	    ),
	    (
	        SELECT
	
	        IF (
	            substr(
	                oldfather.license_number,
	                1,
	                2
	            ) = 'TP',
	            oldfather.license_number,
	            NULL
	        ) tp_number
	        FROM
	            wms_mtl_onhand_quantities_detail child
	        INNER JOIN wms_mtl_onhand_quantities_detail father ON child.parent_mq_id = father.mq_id
	        INNER JOIN wms_mtl_onhand_quantities_detail oldfather ON father.parent_mq_id = oldfather.mq_id
	        WHERE
	            child.license_number = swpe.tag_number
	        LIMIT 1
	    )
	) tp_number,
	
	IF (
	    (
	        SELECT
	            DOWNRACKSTYPE
	        FROM
	            wms_mtl_onhand_quantities_detail
	        WHERE
	            license_number = swpe.tag_number
	        LIMIT 1
	    ) = 3,
	    'Y',
	    'N'
	) type,
	 (
	    SELECT
	        TC_NUMBER
	    FROM
	        cwms_mobile_tray_lines cmtl
	    WHERE
	        cmtl.TAG_NUMBER = swpe.tag_number
	    ORDER BY
	        CREATION_DATE DESC
	    LIMIT 1
	) tc_number,
	
	IF (
	    (
	        SELECT
	            DOWNRACKSTYPE
	        FROM
	            wms_mtl_onhand_quantities_detail
	        WHERE
	            license_number = swpe.tag_number
	        LIMIT 1
	    ) = 3,
	    1,
	    0
	) is_scan
FROM
    cwms_delivery_lines_all cdla
INNER JOIN hz_cust_accounts hca ON cdla.customer_id = hca.cust_account_id
INNER JOIN sfy_oe_order_headers_all sooh ON sooh.oe_header_id = cdla.oe_header_id
INNER JOIN sfy_wsh_pack_entities swpe ON cdla.oe_header_id = swpe.oe_header_id
INNER JOIN sfy_wsh_packslip_headers_all swph ON swpe.header_id = swph.header_id
INNER JOIN cwms_delivery_plan_all cdpa ON cdpa.DELIVERY_HEADER_ID = cdla.DELIVERY_HEADER_ID
LEFT JOIN mtl_secondary_inventories msit ON msit.organization_id = swpe.organization_id
AND msit.secondary_inventory_name = swpe.subinventory_code
LEFT JOIN pick_pack_link ppl ON ppl.TAG_NUMBER = swpe.TAG_NUMBER
LEFT JOIN mtl_item_locations_kfv milk ON swpe.LOCATOR_ID = milk.INVENTORY_LOCATION_ID
AND milk.ENABLE_FLAG = 1
LEFT JOIN sfy_inv_pd_agent sipa ON sipa.CUST_ACCOUNT_ID = hca.CUST_ACCOUNT_ID
AND sipa.ORGANIZATION_ID = swpe.ORGANIZATION_ID
LEFT JOIN (
    SELECT
        DELIVERY_HEADER_ID,
        SCHEDULE_STAGE,
        group_concat(CAR_NUMBER) CAR_NUMBER,
        group_concat(DISTINCT LOGISTIC_PROVIDER) LOGISTIC_PROVIDER
    FROM
        wms_delivery_car_detail
    GROUP BY
        DELIVERY_HEADER_ID
) wdcd ON cdpa.DELIVERY_HEADER_ID = wdcd.DELIVERY_HEADER_ID
LEFT JOIN wms_bill_platform wbp ON wbp.PLATFORM_CODE = wdcd.SCHEDULE_STAGE
AND wbp.PLATFORM_ENABLE_FLAG = 1
WHERE
    swpe.tag_number IS NOT NULL
AND swpe.pack_number IS NOT NULL
AND swpe. STATUS != 'X'
AND cdpa.approve_status = 'Y'
AND cdpa.inv_approve_status = 'Y'
AND hca.account_number = 'GPS21017802'
AND cdla.act_delivery_date = '2024-06-26'
AND ifnull(
    swpe.delivery_date,
    cdla.act_delivery_date
) >= cdla.act_delivery_date
ORDER BY
    milk.CONCATENATED_SEGMENTS

1、问题展示

查询效率：3w条数据，耗费14s

2、问题排查

2.1、操作思路

通过执行计划看到wms_delivery_car_detail的执行计划好像有优化空间，先将这张表的关联移除后 查看执行效率，以确认这张表影响的程度

2.2、执行结果

查询效率13.9s，发现移除后并没有显著的提高，说明这个子查询的执行计划并没有很大的效率问题

3、大胆假设，小心求证

3.1、操作思路

那么接下来看看其他执行计划，发现而且在字段上的子查询 有很多，假如我们把所有字段中的子查询都移除了会有什么效果------移除了执行计划中select_type=DEPENDENT SUBQUERY的子查询后，只需要1.3s就拿到查询结果了，执行计划如图所示，由此可知字段上的子查询多了，结果集大时会对查询效率有很大的影响。

既然找到了问题出现在子查询上，但这些字段还是要查的，只是我们得换种方式，目的是移除子查询的情况下依然查询所需字段 ，那就要修改为连接查询 的方式，如先把关联相同表的多个子查询通过表关联的方式合并为一次关联。

3.2、子查询分析

子查询表	对应的子查询数量	代码行数
`cwms_delivery_attachment_all`	2个	第21至28，34至40
`wms_mtl_onhand_quantities_detail`	2个	第86至95，100至112，115至132，138至144
`sfy_wsh_delivery_headers_all`	1个	第55至62
`cwms_mobile_tray_lines`	1个	第150至158（因为其中的tag_number是唯一的，经业务确认此处的`order by`可移除）

3.3、执行结果

修改为连接查询后，查询耗时仅需要2.6s，执行计划如下:

sql 复制代码

-- 修改后的sql
SELECT DISTINCT
    swpe.tag_number,
    hca.ACCOUNT_NAME customer_name,
    sipa.PIN_LOGO area_number,
    cdla.delivery_header_id,
    swpe.pack_number,
    swph.packslip_number,
    cdpa.transport_mode,
    date_format(
        swpe.inware_date,
        '%Y-%m-%d %H:%i:%s'
    ) in_warehouse_date,
    DATE(cdla.act_delivery_date) act_delivery_date,
    wbp.PLATFORM_NAME schedule_stage_mir,
    sooh.order_number,
    swph.lot_number,
    milk.ATTRIBUTE14,
    ifnull(cdaa.stock_scan_status, 'N') stock_status,
    ifnull(cdaa.comments, NULL) comments,
    ifnull(swdh.delivery_number, NULL) delivery_number,
    ifnull(
        (
            SELECT
                filter1
            FROM
                eos_dict_entry
            WHERE
                DICTTYPEID = 'AUTH_CONFIG'
            LIMIT 1
        ),
        'Y'
    ) zc_power,
    ppl.PICK_NUMBER pd_number,
    IF (
        -- wmoqd.TP_NUMBER是原关联fater.license_number或者oldfather.license_number的值
        substr(wmoqd.TP_NUMBER, 1, 2) = 'TP',
        wmoqd.TP_NUMBER,
        NULL
    ) tp_number,
    IF (wmoqd.DOWNRACKSTYPE = 3, 'Y', 'N') type,
    cmtl.TC_NUMBER tc_number,
    IF (wmoqd.DOWNRACKSTYPE = 3, 1, 0) is_scan
FROM
    cwms_delivery_lines_all cdla
INNER JOIN hz_cust_accounts hca ON cdla.customer_id = hca.cust_account_id
INNER JOIN sfy_oe_order_headers_all sooh ON sooh.oe_header_id = cdla.oe_header_id
INNER JOIN sfy_wsh_pack_entities swpe ON cdla.oe_header_id = swpe.oe_header_id
INNER JOIN sfy_wsh_packslip_headers_all swph ON swpe.header_id = swph.header_id
INNER JOIN cwms_delivery_plan_all cdpa ON cdpa.DELIVERY_HEADER_ID = cdla.DELIVERY_HEADER_ID
LEFT JOIN mtl_secondary_inventories msit ON msit.organization_id = swpe.organization_id
    AND msit.secondary_inventory_name = swpe.subinventory_code
LEFT JOIN pick_pack_link ppl ON ppl.TAG_NUMBER = swpe.TAG_NUMBER
LEFT JOIN mtl_item_locations_kfv milk ON swpe.LOCATOR_ID = milk.INVENTORY_LOCATION_ID
    AND milk.ENABLE_FLAG = 1
LEFT JOIN sfy_inv_pd_agent sipa ON sipa.CUST_ACCOUNT_ID = hca.CUST_ACCOUNT_ID
    AND sipa.ORGANIZATION_ID = swpe.ORGANIZATION_ID
LEFT JOIN (
    SELECT
        DELIVERY_HEADER_ID,
        SCHEDULE_STAGE,
        group_concat(CAR_NUMBER) CAR_NUMBER,
        group_concat(DISTINCT LOGISTIC_PROVIDER) LOGISTIC_PROVIDER
    FROM
        wms_delivery_car_detail
    GROUP BY
        DELIVERY_HEADER_ID
) wdcd ON cdpa.DELIVERY_HEADER_ID = wdcd.DELIVERY_HEADER_ID
LEFT JOIN wms_bill_platform wbp ON wbp.PLATFORM_CODE = wdcd.SCHEDULE_STAGE
    AND wbp.PLATFORM_ENABLE_FLAG = 1
-- 主要改动在这里：从子查询迁移到下面左关联
LEFT JOIN cwms_delivery_attachment_all cdaa ON cdaa.PACK_ENTITY_ID=swpe.PACK_ENTITY_ID
LEFT JOIN wms_mtl_onhand_quantities_detail wmoqd ON wmoqd.LICENSE_NUMBER=swpe.TAG_NUMBER AND wmoqd.ORGANIZATION_ID=swpe.ORGANIZATION_ID
LEFT JOIN sfy_wsh_delivery_lines_all swdl ON swdl.TAG_NUMBER=swpe.TAG_NUMBER
LEFT JOIN sfy_wsh_delivery_headers_all swdh ON swdh.DELIVERY_HEADER_ID=swdl.DELIVERY_HEADER_ID
LEFT JOIN cwms_mobile_tray_lines cmtl ON cmtl.TAG_NUMBER=swpe.TAG_NUMBER
WHERE
    swpe.tag_number IS NOT NULL
AND swpe.pack_number IS NOT NULL
AND swpe. STATUS != 'X'
AND cdpa.approve_status = 'Y'
AND cdpa.inv_approve_status = 'Y'
AND hca.account_number = 'GPS21017802'
AND cdla.act_delivery_date = '2024-06-26'
AND ifnull(
    swpe.delivery_date,
    cdla.act_delivery_date
) >= cdla.act_delivery_date
GROUP BY swpe.TAG_NUMBER
ORDER BY
    milk.CONCATENATED_SEGMENTS

总结

当结果集字段中有好几个相同表的子查询时，将子查询修改为连接查询的效率提升会比较大（相当于一行记录处理一次查询）
有时候执行计划可能无法直接看出修改哪里能提升，但能给我们提供优化的思路
在执行计划中看到每个表都走索引了，但是却还是很慢，那我们可以一段一段的、一表一表的排除，找到问题点在哪，而多快能找到主要就取决于经验还有对表的熟悉程度了。