[英]Mysql Join Query optimisation
您好,我正在嘗試使用此查詢運行此select語句,並且要花2個小時才能運行。 我已經設置了所有正確的索引。 但是仍然需要我永遠丟失某些東西,或者將表連接在一起的更有效的方式可以加快查詢速度?
我為連接在一起的所有項目設置了索引,它們的長度和數據類型相同。
SELECT
p.sap_article_id,
p.numeric_line_code,
p.uag_linecode,
p.uag_partnum,
p.part_description,
p.jobber_price,
p.jobber_core,
p.discount1,
p.discount2,
p.uom,
p.product_category,
w.as400_warehouse,
w.atp_qty,
p.updated,
t.regular_discount
FROM part p
LEFT JOIN tabjbmaw t ON t.accountnum = '73050'
AND p.numeric_line_code = t.numeric_line_code
AND p.sub_code = t.sub_code
JOIN warehouse w ON w.sap_article_id = p.sap_article_id;
+----+-------------+-----------+------+--------------------------------------------------+-----------------------+---------+----------------------------------+--------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-----------+------+--------------------------------------------------+-----------------------+---------+----------------------------------+--------+-------------+
| 1 | SIMPLE | part | ALL | PRIMARY,sap_article,part_sap_article_id_fk | NULL | NULL | NULL | 389309 | |
| 1 | SIMPLE | warehouse | ref | article | article | 130 | inventory.part.sap_article_id | 5 | Using where |
| 1 | SIMPLE | tabjbmaw | ref | numeric_line_code_idx,subcode_idx,accountnum_idx | numeric_line_code_idx | 5 | inventory.part.numeric_line_code | 19 | |
+----+-------------+-----------+------+--------------------------------------------------+-----------------------+---------+----------------------------------+--------+-------------+
謝謝您的幫助
+-----------------------------+--------------+------+-----+---------------------+-----------------------------+
| Field | Type | Null | Key | Default | Extra |
+-----------------------------+--------------+------+-----+---------------------+-----------------------------+
| sap_article_id | varchar(24) | NO | PRI | | |
| sap_brand_id | varchar(20) | NO | | NULL | |
| uag_partnum | varchar(20) | NO | MUL | NULL | |
| uag_linecode | varchar(5) | NO | MUL | NULL | |
| cag_partnum | varchar(20) | NO | MUL | NULL | |
| cag_linecode | varchar(5) | NO | | NULL | |
| product_category_legacy | varchar(20) | NO | | NULL | |
| part_description | varchar(128) | NO | | NULL | |
| abc_indicator | varchar(8) | NO | | NULL | |
| pack_code | varchar(8) | NO | | NULL | |
| case_qty | int(11) | NO | | NULL | |
| per_car_qty | int(11) | NO | | NULL | |
| uom | varchar(6) | NO | | NULL | |
| upc_code | varchar(128) | NO | | NULL | |
| jobber_price | float(14,4) | YES | | NULL | |
| jobber_core | float(14,4) | YES | | NULL | |
| date_last_price_change | timestamp | NO | | CURRENT_TIMESTAMP | on update CURRENT_TIMESTAMP |
| weight | float(14,4) | YES | | NULL | |
| weight_unit | varchar(6) | NO | | NULL | |
| dimension_type | varchar(6) | NO | | NULL | |
| length | float(14,4) | YES | | NULL | |
| width | float(14,4) | YES | | NULL | |
| height | float(14,4) | YES | | NULL | |
| updated | tinyint(1) | NO | | 0 | |
| superseded_sap_article_id | varchar(24) | YES | | NULL | |
| last_updated | timestamp | NO | | 0000-00-00 00:00:00 | |
| hour_updated | int(11) | YES | | NULL | |
| discount1 | float | YES | | NULL | |
| discount2 | float | YES | | NULL | |
| product_category | varchar(3) | YES | | NULL | |
| superseded_part_number | varchar(20) | YES | | NULL | |
| sub_code | varchar(3) | YES | MUL | NULL | |
| date_effective_price_change | date | YES | | NULL | |
| numeric_line_code | varchar(3) | YES | MUL | NULL | |
| list | float | YES | | NULL | |
+-----------------------------+--------------+------+-----+---------------------+-----------------------------+
我為連接在一起的所有項目設置了索引
是的,但是我從索引的名稱猜測每個索引只有一個字段。
讓我們看一下describe中的幾列。
| table | possible_keys | key
+-----------+--------------------------------------------------+----------------
| part | PRIMARY,sap_article,part_sap_article_id_fk | NULL
| warehouse | article | article
| tabjbmaw | numeric_line_code_idx,subcode_idx,accountnum_idx | numeric_line_code_idx
它可以為numeric_line_code,subcode和accountnum使用索引,但是只有三個索引,每個索引都有一個字段,沒有索引包含所有字段。 您正在使優化器選擇一個字段索引之一,而不是提供一個可用於所有三個字段的索引。
在表tabjbmaw上添加帶有三個字段numeric_line_code,子代碼和accountnum的索引。
擴展@Sebas答案,您應該首先選擇tabjbmaw:
SELECT
p.sap_article_id,
p.numeric_line_code,
p.uag_linecode,
p.uag_partnum,
p.part_description,
p.jobber_price,
p.jobber_core,
p.discount1,
p.discount2,
p.uom,
p.product_category,
w.as400_warehouse,
w.atp_qty,
p.updated,
t.regular_discount
FROM tabjbmaw t
LEFT JOIN parts p ON p.numeric_line_code = t.numeric_line_code
AND p.sub_code = t.sub_code
JOIN warehouse w ON w.sap_article_id = p.sap_article_id
WHERE t.accountnum = '73050'
;
您可以嘗試將左聯接作為子選擇放入SELECT部分。 這樣“可能”會加快速度。
像這樣:
SELECT
p.sap_article_id,
p.numeric_line_code,
p.uag_linecode,
p.uag_partnum,
p.part_description,
p.jobber_price,
p.jobber_core,
p.discount1,
p.discount2,
p.uom,
p.product_category,
w.as400_warehouse,
w.atp_qty,
p.updated,
(SELECT t.regular_discount FROM tabjbmaw t WHERE t.accountnum = '73050' AND p.numeric_line_code = t.numeric_line_code AND p.sub_code = t.sub_code LIMIT 1)
FROM
part p
JOIN warehouse w ON w.sap_article_id = p.sap_article_id;
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