{"id":103207,"date":"2026-09-10T02:25:18","date_gmt":"2026-09-09T18:25:18","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/103207.html"},"modified":"2026-09-10T02:25:18","modified_gmt":"2026-09-09T18:25:18","slug":"mysql-explain-%e6%80%8e%e4%b9%88%e7%9c%8b%ef%bc%9f%e4%b8%80%e6%9d%a1%e6%85%a2-sql-%e5%88%b0%e5%ba%95%e6%85%a2%e5%9c%a8%e5%93%aa%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/103207.html","title":{"rendered":"MySQL EXPLAIN \u600e\u4e48\u770b\uff1f\u4e00\u6761\u6162 SQL \u5230\u5e95\u6162\u5728\u54ea\uff1f"},"content":{"rendered":"

\u4e0a\u4e00\u7bc7\u6211\u4eec\u8bb2\u4e86 MySQL \u7d22\u5f15\u4e3a\u4ec0\u4e48\u53ef\u80fd\u5931\u6548\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

SELECT<\/span> *<\/span>
\nFROM<\/span> user<\/span>
\nWHERE<\/span> YEAR<\/span>(<\/span>create_time)<\/span> =<\/span> 2026<\/span>;<\/span><\/p>\n

\u6216\u8005：<\/p>\n

SELECT<\/span> *<\/span>
\nFROM<\/span> user<\/span>
\nWHERE<\/span> name LIKE<\/span> '%\u5f20'<\/span>;<\/span><\/p>\n

\u6211\u4eec\u77e5\u9053，\u8fd9\u4e9b\u5199\u6cd5\u901a\u5e38\u4e0d\u5229\u4e8e\u666e\u901a B+Tree \u7d22\u5f15\u8fdb\u884c\u9ad8\u6548\u5b9a\u4f4d\u3002<\/p>\n

\u4f46\u5b9e\u9645\u5f00\u53d1\u4e2d，\u4e0d\u80fd\u53ea\u9760\u7ecf\u9a8c\u5224\u65ad：<\/p>\n

\u8fd9\u4e2a SQL \u5e94\u8be5\u8d70\u7d22\u5f15\u5427？<\/p>\n

\u56e0\u4e3a MySQL \u4f18\u5316\u5668\u6700\u7ec8\u53ef\u80fd\u9009\u62e9：<\/p>\n

\u5168\u8868\u626b\u63cf<\/p>\n

\u4e5f\u53ef\u80fd\u9009\u62e9：<\/p>\n

\u7d22\u5f15\u626b\u63cf<\/p>\n

\u751a\u81f3\u67d0\u4e9b\u770b\u8d77\u6765\u80fd\u8d70\u7d22\u5f15\u7684 SQL，\u4f18\u5316\u5668\u4e5f\u53ef\u80fd\u8ba4\u4e3a\u5168\u8868\u626b\u63cf\u66f4\u5212\u7b97\u3002<\/p>\n

\u6240\u4ee5\u771f\u6b63\u5206\u6790 SQL \u65f6，\u6211\u4eec\u9700\u8981\u4e00\u4e2a\u5de5\u5177：<\/p>\n

EXPLAIN<\/span><\/p>\n

1. EXPLAIN \u662f\u4ec0\u4e48？<\/h3>\n

EXPLAIN \u53ef\u4ee5\u67e5\u770b MySQL \u4e3a\u4e00\u6761 SQL \u9009\u62e9\u7684\u6267\u884c\u8ba1\u5212\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

EXPLAIN<\/span>
\nSELECT<\/span> *<\/span>
\nFROM<\/span> user<\/span>
\nWHERE<\/span> id =<\/span> 10001<\/span>;<\/span><\/p>\n

\u5b83\u4f1a\u544a\u8bc9\u6211\u4eec：<\/p>\n

\u51c6\u5907\u600e\u4e48\u67e5？<\/p>\n

\u53ef\u80fd\u4f7f\u7528\u54ea\u4e9b\u7d22\u5f15？<\/p>\n

\u6700\u7ec8\u9009\u62e9\u54ea\u4e2a\u7d22\u5f15？<\/p>\n

\u9884\u8ba1\u626b\u63cf\u591a\u5c11\u884c？<\/p>\n

\u662f\u5426\u9700\u8981\u989d\u5916\u6392\u5e8f？<\/p>\n

MySQL \u5728\u771f\u6b63\u6267\u884c\u67e5\u8be2\u4e4b\u524d，\u5148\u628a\u81ea\u5df1\u7684\u67e5\u8be2\u65b9\u6848\u5c55\u793a\u7ed9\u6211\u4eec\u3002<\/p>\n

\u666e\u901a EXPLAIN \u5c55\u793a\u7684\u662f\u4f18\u5316\u5668\u9009\u62e9\u7684\u8ba1\u5212\u548c\u4f30\u7b97\u4fe1\u606f，\u5e76\u4e0d\u7b49\u4e8e\u8fd9\u6761 SQL \u5df2\u7ecf\u5b9e\u9645\u6267\u884c\u5b8c\u6bd5\u3002<\/p>\n

2. \u5148\u51c6\u5907\u4e00\u5f20\u793a\u4f8b\u8868<\/h2>\n

\u5047\u8bbe\u6709\u4e00\u5f20\u8ba2\u5355\u8868：<\/p>\n

CREATE<\/span> TABLE<\/span> orders (<\/span>
\n id BIGINT<\/span> PRIMARY<\/span> KEY<\/span>,<\/span>
\n user_id BIGINT<\/span> NOT<\/span> NULL<\/span>,<\/span>
\n status<\/span> INT<\/span> NOT<\/span> NULL<\/span>,<\/span>
\n create_time DATETIME<\/span> NOT<\/span> NULL<\/span>,<\/span>
\n amount DECIMAL<\/span>(<\/span>10<\/span>,<\/span> 2<\/span>)<\/span> NOT<\/span> NULL<\/span>
\n)<\/span>;<\/span><\/p>\n

\u5e76\u4e14\u5efa\u7acb\u8054\u5408\u7d22\u5f15：<\/p>\n

CREATE<\/span> INDEX<\/span> idx_user_status_time
\nON<\/span> orders(<\/span>user_id,<\/span> status<\/span>,<\/span> create_time)<\/span>;<\/span><\/p>\n

\u6211\u4eec\u7ecf\u5e38\u67e5\u8be2：<\/p>\n

SELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> user_id =<\/span> 10001<\/span>
\n AND<\/span> status<\/span> =<\/span> 1<\/span>
\nORDER<\/span> BY<\/span> create_time DESC<\/span>
\nLIMIT<\/span> 20<\/span>;<\/span><\/p>\n

\u63a5\u4e0b\u6765\u5c31\u7528\u8fd9\u5f20\u8868\u7406\u89e3 EXPLAIN\u3002<\/p>\n

3. EXPLAIN \u6700\u5e38\u770b\u7684\u51e0\u4e2a\u5b57\u6bb5<\/h2>\n

\u6267\u884c：<\/p>\n

EXPLAIN<\/span>
\nSELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> user_id =<\/span> 10001<\/span>
\n AND<\/span> status<\/span> =<\/span> 1<\/span>
\nORDER<\/span> BY<\/span> create_time DESC<\/span>
\nLIMIT<\/span> 20<\/span>;<\/span><\/p>\n

\u4f1a\u5f97\u5230\u4e00\u5f20\u6267\u884c\u8ba1\u5212\u8868\u3002<\/p>\n

\u4e0d\u540c MySQL \u7248\u672c\u3001SQL \u548c\u6570\u636e\u5206\u5e03，\u5177\u4f53\u7ed3\u679c\u4f1a\u4e0d\u540c，\u4f46\u6700\u503c\u5f97\u5173\u6ce8\u7684\u662f：<\/p>\n\n\u5b57\u6bb5\u4e3b\u8981\u542b\u4e49<\/tr>\n\n\n\n\n\n\n\n\n
type<\/td>\n\u8bbf\u95ee\u8868\u7684\u65b9\u5f0f<\/td>\n<\/tr>\n
possible_keys<\/td>\n\u53ef\u80fd\u4f7f\u7528\u7684\u7d22\u5f15<\/td>\n<\/tr>\n
key<\/td>\n\u5b9e\u9645\u9009\u62e9\u7684\u7d22\u5f15<\/td>\n<\/tr>\n
key_len<\/td>\n\u4f7f\u7528\u7684\u7d22\u5f15\u952e\u957f\u5ea6<\/td>\n<\/tr>\n
rows<\/td>\n\u9884\u8ba1\u9700\u8981\u68c0\u67e5\u7684\u884c\u6570<\/td>\n<\/tr>\n
filtered<\/td>\n\u9884\u8ba1\u6709\u591a\u5c11\u6bd4\u4f8b\u7684\u884c\u80fd\u901a\u8fc7\u6761\u4ef6<\/td>\n<\/tr>\n
Extra<\/td>\n\u989d\u5916\u6267\u884c\u4fe1\u606f<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

type
\n \u2193
\n\u600e\u4e48\u67e5？<\/p>\n

key
\n \u2193
\n\u7528\u54ea\u4e2a\u7d22\u5f15？<\/p>\n

rows
\n \u2193
\n\u9884\u8ba1\u67e5\u591a\u5c11？<\/p>\n

Extra
\n \u2193
\n\u6709\u6ca1\u6709\u989d\u5916\u64cd\u4f5c？<\/p>\n

4. type：MySQL \u51c6\u5907\u600e\u4e48\u67e5？<\/h2>\n

type \u662f\u5165\u95e8\u9636\u6bb5\u975e\u5e38\u91cd\u8981\u7684\u5b57\u6bb5\u3002<\/p>\n

\u5b83\u8868\u793a MySQL \u5bf9\u8fd9\u5f20\u8868\u91c7\u7528\u7684\u8bbf\u95ee\u65b9\u5f0f\u3002<\/p>\n

\u5e38\u89c1\u7684\u6709：<\/p>\n

system
\nconst
\neq_ref
\nref
\nrange
\nindex
\nALL<\/p>\n

5. const：\u901a\u8fc7\u552f\u4e00\u6761\u4ef6\u627e\u5230\u4e00\u6761\u8bb0\u5f55<\/h3>\n

\u4f8b\u5982：<\/p>\n

EXPLAIN<\/span>
\nSELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> id =<\/span> 10001<\/span>;<\/span><\/p>\n

\u56e0\u4e3a：<\/p>\n

id<\/p>\n

\u662f\u4e3b\u952e\u3002<\/p>\n

MySQL \u53ef\u4ee5\u901a\u8fc7\u4e3b\u952e\u7d22\u5f15\u76f4\u63a5\u5b9a\u4f4d\u5230\u4e00\u6761\u8bb0\u5f55\u3002<\/p>\n

\u6240\u4ee5\u901a\u5e38\u4f1a\u770b\u5230：<\/p>\n

type = const<\/p>\n

\u53ef\u4ee5\u7b80\u5355\u7406\u89e3\u6210：<\/p>\n

\u901a\u8fc7\u4e3b\u952e\u6216\u552f\u4e00\u7d22\u5f15\u7684\u7b49\u503c\u6761\u4ef6，\u6700\u591a\u786e\u5b9a\u4e00\u6761\u8bb0\u5f55\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

WHERE<\/span> id =<\/span> 10001<\/span><\/p>\n

\u6216\u8005\u67d0\u4e2a\u975e\u7a7a\u552f\u4e00\u7d22\u5f15\u4e0a\u7684\u7b49\u503c\u67e5\u8be2\u3002<\/p>\n

\u8fd9\u79cd\u8bbf\u95ee\u65b9\u5f0f\u901a\u5e38\u975e\u5e38\u9ad8\u6548\u3002<\/p>\n

6. ref：\u901a\u8fc7\u666e\u901a\u7d22\u5f15\u67e5\u627e\u5339\u914d\u8bb0\u5f55<\/h2>\n

\u5047\u8bbe\u6709：<\/p>\n

CREATE<\/span> INDEX<\/span> idx_status
\nON<\/span> orders(<\/span>status<\/span>)<\/span>;<\/span><\/p>\n

\u6267\u884c：<\/p>\n

EXPLAIN<\/span>
\nSELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> status<\/span> =<\/span> 1<\/span>;<\/span><\/p>\n

\u56e0\u4e3a：<\/p>\n

status<\/p>\n

\u4e0d\u662f\u552f\u4e00\u5b57\u6bb5\u3002<\/p>\n

\u53ef\u80fd\u6709\u5f88\u591a\u8ba2\u5355\u90fd\u662f：<\/p>\n

status = 1<\/p>\n

\u6240\u4ee5 MySQL \u9700\u8981\u627e\u5230\u4e00\u7ec4\u5339\u914d\u8bb0\u5f55\u3002<\/p>\n

\u8fd9\u65f6\u5019\u53ef\u80fd\u51fa\u73b0：<\/p>\n

type = ref<\/p>\n

\u53ef\u4ee5\u7406\u89e3\u6210：<\/p>\n

\u901a\u8fc7\u975e\u552f\u4e00\u7d22\u5f15\u7684\u7b49\u503c\u6761\u4ef6，\u67e5\u627e\u4e00\u7ec4\u5339\u914d\u8bb0\u5f55\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

status = 1<\/p>\n

\u53ef\u80fd\u5339\u914d：<\/p>\n

100 \u6761<\/p>\n

1000 \u6761<\/p>\n

10 \u4e07\u6761<\/p>\n

\u6240\u4ee5：<\/p>\n

ref<\/p>\n

\u4e0d\u4ee3\u8868\u4e00\u5b9a\u53ea\u67e5\u4e00\u6761\u3002<\/p>\n

7. range：\u8303\u56f4\u626b\u63cf<\/h2>\n

\u4f8b\u5982：<\/p>\n

EXPLAIN<\/span>
\nSELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> create_time >=<\/span> '2026-01-01'<\/span>
\n AND<\/span> create_time <<\/span> '2027-01-01'<\/span>;<\/span><\/p>\n

\u5982\u679c create_time \u6709\u5408\u9002\u7d22\u5f15，MySQL \u53ef\u80fd\u4f7f\u7528：<\/p>\n

type = range<\/p>\n

\u4e5f\u5c31\u662f：<\/p>\n

\u8303\u56f4\u626b\u63cf<\/p>\n

\u53ef\u4ee5\u7406\u89e3\u6210：<\/p>\n

B+Tree
\n \u2193
\n\u5b9a\u4f4d\u8d77\u59cb\u4f4d\u7f6e
\n \u2193
\n\u987a\u5e8f\u626b\u63cf
\n \u2193
\n\u5230\u7ed3\u675f\u4f4d\u7f6e\u505c\u6b62<\/p>\n

\u5e38\u89c1\u8303\u56f4\u6761\u4ef6\u5305\u62ec：<\/p>\n

><\/span>
\n<<\/span>
\n>=<\/span>
\n<=<\/span>
\nBETWEEN<\/span>
\nIN<\/span> (<\/span>.<\/span>.<\/span>.<\/span>)<\/span><\/p>\n

\u4e0d\u8fc7\u8fd9\u4e9b\u64cd\u4f5c\u7b26\u5e76\u4e0d\u4fdd\u8bc1\u4e00\u5b9a\u51fa\u73b0 range，\u6700\u7ec8\u4ecd\u7136\u53d6\u51b3\u4e8e\u4f18\u5316\u5668\u9009\u62e9\u3002<\/p>\n

8. index：\u626b\u63cf\u6574\u4e2a\u7d22\u5f15<\/h2>\n

\u8fd9\u4e2a\u5b57\u6bb5\u7279\u522b\u5bb9\u6613\u8bef\u89e3\u3002<\/p>\n

\u5f88\u591a\u4eba\u770b\u5230：<\/p>\n

type = index<\/p>\n

\u4f1a\u8ba4\u4e3a：<\/p>\n

\u592a\u597d\u4e86，\u4f7f\u7528\u7d22\u5f15\u4e86，\u80af\u5b9a\u5f88\u5feb\u3002<\/p>\n

\u5176\u5b9e\u4e0d\u4e00\u5b9a\u3002<\/p>\n

index \u901a\u5e38\u8868\u793a：<\/p>\n

\u626b\u63cf\u6574\u4e2a\u7d22\u5f15<\/p>\n

\u4f8b\u5982：<\/p>\n

B+Tree
\n \u2193
\n\u4ece\u5934\u5f00\u59cb\u626b\u63cf
\n \u2193
\n\u4e00\u76f4\u626b\u63cf\u5230\u540e\u9762<\/p>\n

\u5b83\u548c：<\/p>\n

range<\/p>\n

\u4e0d\u4e00\u6837\u3002<\/p>\n

range \u662f：<\/p>\n

\u5b9a\u4f4d\u5230\u67d0\u4e2a\u8303\u56f4
\n \u2193
\n\u53ea\u626b\u63cf\u8fd9\u4e2a\u8303\u56f4<\/p>\n

\u800c index \u53ef\u80fd\u662f：<\/p>\n

\u6574\u4e2a\u7d22\u5f15\u90fd\u8981\u626b\u63cf<\/p>\n

\u6240\u4ee5：<\/p>\n

\u4f7f\u7528\u7d22\u5f15，\u4e0d\u4ee3\u8868\u5c31\u4e00\u5b9a\u662f\u9ad8\u6548\u7684\u7d22\u5f15\u67e5\u627e\u3002<\/p>\n

\u6709\u65f6\u5019\u626b\u63cf\u6574\u4e2a\u4e8c\u7ea7\u7d22\u5f15\u6bd4\u626b\u63cf\u6574\u5f20\u8868\u66f4\u4fbf\u5b9c，\u4f46\u5b83\u4ecd\u7136\u53ef\u80fd\u9700\u8981\u68c0\u67e5\u5927\u91cf\u7d22\u5f15\u8bb0\u5f55\u3002<\/p>\n

9. ALL：\u5168\u8868\u626b\u63cf<\/h2>\n

\u5982\u679c\u770b\u5230：<\/p>\n

type = ALL<\/p>\n

\u901a\u5e38\u8868\u793a：<\/p>\n

Full Table Scan<\/p>\n

\u4e5f\u5c31\u662f\u5168\u8868\u626b\u63cf\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

EXPLAIN<\/span>
\nSELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> amount ><\/span> 100<\/span>;<\/span><\/p>\n

\u5047\u8bbe amount \u6ca1\u6709\u7d22\u5f15\u3002<\/p>\n

MySQL \u53ef\u80fd\u53ea\u80fd：<\/p>\n

\u7b2c 1 \u884c
\n \u2193
\n\u7b2c 2 \u884c
\n \u2193
\n\u7b2c 3 \u884c
\n \u2193
\n…<\/p>\n

\u9010\u884c\u68c0\u67e5\u3002<\/p>\n

\u4f46\u8fd9\u91cc\u4e00\u5b9a\u8981\u8bb0\u4f4f：<\/p>\n

ALL \u4e0d\u4e00\u5b9a\u4ee3\u8868 SQL \u5199\u9519\u4e86\u3002<\/p>\n

\u5982\u679c\u8868\u53ea\u6709：<\/p>\n

100 \u884c<\/p>\n

\u5168\u8868\u626b\u63cf\u53ef\u80fd\u975e\u5e38\u5feb\u3002<\/p>\n

\u5982\u679c\u67e5\u8be2\u9700\u8981\u8fd4\u56de：<\/p>\n

90% \u7684\u6570\u636e<\/p>\n

\u5168\u8868\u626b\u63cf\u4e5f\u53ef\u80fd\u6bd4\u5927\u91cf\u56de\u8868\u66f4\u5212\u7b97\u3002<\/p>\n

\u6240\u4ee5\u4e0d\u80fd\u7b80\u5355\u5730：<\/p>\n

type = ALL
\n \u2193
\n\u5fc5\u987b\u52a0\u7d22\u5f15<\/p>\n

\u800c\u5e94\u8be5\u7ee7\u7eed\u770b：<\/p>\n

rows<\/p>\n

\u67e5\u8be2\u6761\u4ef6<\/p>\n

\u8fd4\u56de\u6570\u636e\u91cf<\/p>\n

\u5b9e\u9645\u6267\u884c\u8017\u65f6<\/p>\n

10. type \u600e\u4e48\u770b？<\/h2>\n

const
\n \u2193
\n\u552f\u4e00\u6761\u4ef6\u5b9a\u4f4d\u4e00\u6761<\/p>\n

ref
\n \u2193
\n\u666e\u901a\u7d22\u5f15\u7b49\u503c\u67e5\u627e<\/p>\n

range
\n \u2193
\n\u7d22\u5f15\u8303\u56f4\u626b\u63cf<\/p>\n

index
\n \u2193
\n\u626b\u63cf\u6574\u4e2a\u7d22\u5f15<\/p>\n

ALL
\n \u2193
\n\u5168\u8868\u626b\u63cf<\/p>\n

\u4e00\u822c\u6765\u8bf4：<\/p>\n

\u7cbe\u51c6\u5b9a\u4f4d
\n \u2193
\n\u901a\u5e38\u6bd4\u5927\u91cf\u626b\u63cf\u66f4\u6709\u4f18\u52bf<\/p>\n

\u4f46\u662f\u771f\u6b63\u5feb\u4e0d\u5feb，\u8fd8\u8981\u770b：<\/p>\n

\u626b\u63cf\u591a\u5c11\u6570\u636e<\/p>\n

\u662f\u5426\u56de\u8868<\/p>\n

\u662f\u5426\u6392\u5e8f<\/p>\n

\u662f\u5426\u8bbf\u95ee\u5927\u91cf\u78c1\u76d8\u9875<\/p>\n

11. possible_keys：\u53ef\u80fd\u4f7f\u7528\u54ea\u4e9b\u7d22\u5f15？<\/h2>\n

\u5047\u8bbe：<\/p>\n

CREATE<\/span> INDEX<\/span> idx_user_id
\nON<\/span> orders(<\/span>user_id)<\/span>;<\/span><\/p>\n

CREATE<\/span> INDEX<\/span> idx_status
\nON<\/span> orders(<\/span>status<\/span>)<\/span>;<\/span><\/p>\n

\u6267\u884c：<\/p>\n

EXPLAIN<\/span>
\nSELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> user_id =<\/span> 10001<\/span>
\n AND<\/span> status<\/span> =<\/span> 1<\/span>;<\/span><\/p>\n

\u4f18\u5316\u5668\u53ef\u80fd\u8ba4\u4e3a：<\/p>\n

idx_user_id<\/p>\n

idx_status<\/p>\n

\u90fd\u6709\u673a\u4f1a\u7528\u4e8e\u67e5\u8be2\u3002<\/p>\n

\u4e8e\u662f：<\/p>\n

possible_keys<\/p>\n

\u53ef\u80fd\u663e\u793a：<\/p>\n

idx_user_id,idx_status<\/p>\n

\u5b83\u7684\u610f\u601d\u662f：<\/p>\n

\u8fd9\u4e9b\u7d22\u5f15\u53ef\u80fd\u7528\u4e8e\u67e5\u627e\u8fd9\u5f20\u8868\u4e2d\u7684\u8bb0\u5f55\u3002<\/p>\n

\u4f46\u5e76\u4e0d\u4ee3\u8868：<\/p>\n

\u8fd9\u4e9b\u7d22\u5f15\u5168\u90e8\u90fd\u4f1a\u4f7f\u7528<\/p>\n

\u771f\u6b63\u9009\u62e9\u54ea\u4e2a，\u8981\u770b：<\/p>\n

key<\/p>\n

12. key：\u5b9e\u9645\u9009\u62e9\u4e86\u54ea\u4e2a\u7d22\u5f15<\/h2>\n

\u4f8b\u5982：<\/p>\n

possible_keys = idx_user_id,idx_status<\/p>\n

key = idx_user_id<\/p>\n

\u8868\u793a\u4f18\u5316\u5668\u6700\u7ec8\u9009\u62e9：<\/p>\n

idx_user_id<\/p>\n

\u4f5c\u4e3a\u8bbf\u95ee\u7d22\u5f15\u3002<\/p>\n

\u5982\u679c：<\/p>\n

key = NULL<\/p>\n

\u901a\u5e38\u8868\u793a\u6ca1\u6709\u9009\u62e9\u7d22\u5f15\u4f5c\u4e3a\u5f53\u524d\u8868\u7684\u8bbf\u95ee\u8def\u5f84\u3002<\/p>\n

\u4f46\u662f：<\/p>\n

key \u4e0d\u4e3a NULL，\u4e5f\u4e0d\u4ee3\u8868\u8fd9\u6761 SQL \u4e00\u5b9a\u5f88\u5feb\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

type = index<\/p>\n

key = idx_user_id<\/p>\n

\u53ef\u80fd\u4ecd\u7136\u662f\u5728\u626b\u63cf\u6574\u4e2a\u7d22\u5f15\u3002<\/p>\n

\u6240\u4ee5：<\/p>\n

key<\/p>\n

\u8981\u548c：<\/p>\n

type
\nrows
\nExtra<\/p>\n

\u4e00\u8d77\u770b\u3002<\/p>\n

13. key_len：\u8054\u5408\u7d22\u5f15\u7528\u5230\u4e86\u591a\u5c11<\/h2>\n

\u8054\u5408\u7d22\u5f15：<\/p>\n

CREATE<\/span> INDEX<\/span> idx_user_status_time
\nON<\/span> orders(<\/span>user_id,<\/span> status<\/span>,<\/span> create_time)<\/span>;<\/span><\/p>\n

\u5047\u8bbe\u67e5\u8be2：<\/p>\n

EXPLAIN<\/span>
\nSELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> user_id =<\/span> 10001<\/span>
\n AND<\/span> status<\/span> =<\/span> 1<\/span>;<\/span><\/p>\n

\u6211\u4eec\u60f3\u77e5\u9053：<\/p>\n

\u8054\u5408\u7d22\u5f15\u7528\u5230\u4e86\u54ea\u4e9b\u5217？<\/p>\n

\u8fd9\u65f6\u5019\u53ef\u4ee5\u53c2\u8003：<\/p>\n

key_len<\/p>\n

\u5b83\u8868\u793a MySQL \u4e3a\u6240\u9009\u7d22\u5f15\u4f7f\u7528\u7684\u952e\u957f\u5ea6，\u5355\u4f4d\u662f\u5b57\u8282\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

\u53ea\u5229\u7528 user_id<\/p>\n

\u548c<\/p>\n

\u5229\u7528 user_id + status<\/p>\n

\u5bf9\u5e94\u7684 key_len \u53ef\u80fd\u4e0d\u540c\u3002<\/p>\n

\u4f46\u8fd9\u91cc\u8981\u6ce8\u610f：<\/p>\n

\u4e0d\u8981\u53ea\u9760 key_len \u7684\u6570\u5b57，\u673a\u68b0\u5730\u5224\u65ad\u201c\u7528\u4e86\u51e0\u4e2a\u5b57\u6bb5\u201d\u3002<\/p>\n

\u56e0\u4e3a\u5b83\u8fd8\u4f1a\u53d7\u5230：<\/p>\n

\u5b57\u6bb5\u7c7b\u578b<\/p>\n

\u662f\u5426\u5141\u8bb8 NULL<\/p>\n

\u5b57\u7b26\u96c6<\/p>\n

\u7d22\u5f15\u5217\u5b9a\u4e49<\/p>\n

\u7b49\u56e0\u7d20\u5f71\u54cd\u3002<\/p>\n

\u800c\u4e14 key_len \u4e5f\u4e0d\u80fd\u5b8c\u6574\u8bf4\u660e\u67d0\u4e2a\u5b57\u6bb5\u7a76\u7adf\u7528\u4e8e\u8303\u56f4\u5b9a\u4f4d，\u8fd8\u662f\u7528\u4e8e\u540e\u7eed\u8fc7\u6ee4\u3002<\/p>\n

\u6240\u4ee5\u5b83\u66f4\u9002\u5408：<\/p>\n

\u8f85\u52a9\u5224\u65ad\u8054\u5408\u7d22\u5f15\u4f7f\u7528\u60c5\u51b5<\/p>\n

\u800c\u4e0d\u662f\u5355\u72ec\u4f5c\u4e3a\u6700\u7ec8\u7ed3\u8bba\u3002<\/p>\n

14. rows：\u9884\u8ba1\u9700\u8981\u68c0\u67e5\u591a\u5c11\u884c？<\/h2>\n

\u8fd9\u662f\u5206\u6790\u6162 SQL \u65f6\u975e\u5e38\u91cd\u8981\u7684\u5b57\u6bb5\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

rows = 10<\/p>\n

\u53ef\u4ee5\u7406\u89e3\u6210\u4f18\u5316\u5668\u9884\u8ba1：<\/p>\n

\u5927\u7ea6\u68c0\u67e5 10 \u884c<\/p>\n

\u800c：<\/p>\n

rows = 1000000<\/p>\n

\u5219\u8868\u793a\u9884\u8ba1\u9700\u8981\u68c0\u67e5：<\/p>\n

\u5927\u7ea6 100 \u4e07\u884c<\/p>\n

\u5982\u679c\u4e00\u4e2a SQL：<\/p>\n

type = ALL<\/p>\n

rows = 1000000<\/p>\n

\u90a3\u5c31\u503c\u5f97\u91cd\u70b9\u5173\u6ce8\u3002<\/p>\n

\u4f46\u8981\u6ce8\u610f：<\/p>\n

\u666e\u901a EXPLAIN \u4e2d\u7684 rows \u662f\u4f30\u7b97\u503c，\u4e0d\u662f\u5b9e\u9645\u6267\u884c\u540e\u7cbe\u786e\u7edf\u8ba1\u7684\u884c\u6570\u3002
\n\u4f18\u5316\u5668\u4f1a\u6839\u636e\u7edf\u8ba1\u4fe1\u606f\u4f30\u7b97\u6210\u672c，\u56e0\u6b64\u53ef\u80fd\u5b58\u5728\u8bef\u5dee\u3002<\/p>\n

15. filtered：\u9884\u8ba1\u8fc7\u6ee4\u540e\u5269\u591a\u5c11<\/h2>\n

\u5047\u8bbe：<\/p>\n

rows = 10000<\/p>\n

filtered = 10.00<\/p>\n

\u53ef\u4ee5\u7b80\u5355\u7406\u89e3\u6210：<\/p>\n

\u9884\u8ba1\u68c0\u67e5 10000 \u884c<\/p>\n

\u5176\u4e2d\u5927\u7ea6：<\/p>\n

10%<\/p>\n

\u80fd\u591f\u901a\u8fc7\u5f53\u524d\u8868\u7684\u6761\u4ef6\u3002<\/p>\n

\u4e5f\u5c31\u662f：<\/p>\n

10000 \u00d7 10%
\n=
\n1000 \u884c<\/p>\n

\u53ef\u80fd\u7ee7\u7eed\u8fdb\u5165\u540e\u7eed\u5904\u7406\u3002<\/p>\n

\u6240\u4ee5：<\/p>\n

rows<\/p>\n

\u5173\u6ce8\u7684\u662f：<\/p>\n

\u9884\u8ba1\u68c0\u67e5\u591a\u5c11\u884c<\/p>\n

\u800c：<\/p>\n

filtered<\/p>\n

\u5173\u6ce8\u7684\u662f：<\/p>\n

\u9884\u8ba1\u6709\u591a\u5c11\u6bd4\u4f8b\u901a\u8fc7\u6761\u4ef6<\/p>\n

\u4e0d\u8fc7\u8fd9\u4e24\u4e2a\u503c\u90fd\u662f\u4f30\u7b97，\u4e0d\u8981\u628a\u5b83\u4eec\u5f53\u6210\u771f\u5b9e\u6267\u884c\u7ed3\u679c\u3002<\/p>\n

16. Extra：\u6709\u6ca1\u6709\u989d\u5916\u64cd\u4f5c<\/h2>\n

Extra \u662f\u53e6\u4e00\u4e2a\u975e\u5e38\u503c\u5f97\u5173\u6ce8\u7684\u5b57\u6bb5\u3002<\/p>\n

\u5e38\u89c1\u5185\u5bb9\u5305\u62ec：<\/p>\n

Using where<\/p>\n

Using index<\/p>\n

Using index condition<\/p>\n

Using filesort<\/p>\n

Using temporary<\/p>\n

17. Using where：\u8fd8\u9700\u8981\u8fc7\u6ee4<\/h2>\n

\u4f8b\u5982：<\/p>\n

SELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> status<\/span> =<\/span> 1<\/span>;<\/span><\/p>\n

\u6267\u884c\u8ba1\u5212\u4e2d\u53ef\u80fd\u51fa\u73b0：<\/p>\n

Using where<\/p>\n

\u8868\u793a：<\/p>\n

MySQL \u8fd8\u9700\u8981\u6839\u636e WHERE \u6761\u4ef6\u8fc7\u6ee4\u8bb0\u5f55<\/p>\n

\u4f46\u8fd9\u91cc\u8981\u6ce8\u610f：<\/p>\n

Using where \u4e0d\u4ee3\u8868\u6ca1\u6709\u4f7f\u7528\u7d22\u5f15\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

type = range<\/p>\n

key = idx_create_time<\/p>\n

Extra = Using where<\/p>\n

\u4ecd\u7136\u53ef\u80fd\u5df2\u7ecf\u5229\u7528\u7d22\u5f15\u5b8c\u6210\u4e86\u8303\u56f4\u5b9a\u4f4d\u3002<\/p>\n

\u53ea\u662f\u540e\u9762\u8fd8\u9700\u8981\u7ee7\u7eed\u5224\u65ad\u67d0\u4e9b\u6761\u4ef6\u3002<\/p>\n

\u6240\u4ee5\u4e0d\u8981\u770b\u5230：<\/p>\n

Using where<\/p>\n

\u5c31\u8ba4\u4e3a：<\/p>\n

\u7d22\u5f15\u5931\u6548<\/p>\n

18. Using index：\u8986\u76d6\u7d22\u5f15<\/h2>\n

\u5047\u8bbe：<\/p>\n

CREATE<\/span> INDEX<\/span> idx_user_status
\nON<\/span> orders(<\/span>user_id,<\/span> status<\/span>)<\/span>;<\/span><\/p>\n

\u6267\u884c：<\/p>\n

SELECT<\/span> user_id,<\/span> status<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> user_id =<\/span> 10001<\/span>;<\/span><\/p>\n

\u67e5\u8be2\u9700\u8981：<\/p>\n

user_id<\/p>\n

status<\/p>\n

\u90fd\u5728\u7d22\u5f15\u4e2d\u3002<\/p>\n

\u56e0\u6b64 MySQL \u53ef\u80fd\u76f4\u63a5\u4ece\u7d22\u5f15\u4e2d\u83b7\u53d6\u7ed3\u679c：<\/p>\n

\u4e8c\u7ea7\u7d22\u5f15
\n \u2193
\n\u627e\u5230\u9700\u8981\u7684\u5b57\u6bb5
\n \u2193
\n\u76f4\u63a5\u8fd4\u56de<\/p>\n

\u4e0d\u9700\u8981\u518d\u56de\u8868\u8bfb\u53d6\u5b8c\u6574\u884c\u3002<\/p>\n

\u8fd9\u5c31\u662f：<\/p>\n

\u8986\u76d6\u7d22\u5f15<\/p>\n

\u6267\u884c\u8ba1\u5212\u4e2d\u53ef\u80fd\u51fa\u73b0：<\/p>\n

Using index<\/p>\n

\u6240\u4ee5：<\/p>\n

Using index \u901a\u5e38\u8868\u793a\u67e5\u8be2\u6240\u9700\u7684\u5217\u53ef\u4ee5\u76f4\u63a5\u4ece\u7d22\u5f15\u4e2d\u83b7\u53d6\u3002<\/p>\n

\u4f46\u8981\u6ce8\u610f：<\/p>\n

type = index<\/p>\n

\u548c：<\/p>\n

Extra = Using index<\/p>\n

\u4e0d\u662f\u4e00\u56de\u4e8b\u3002<\/p>\n

\u524d\u8005：<\/p>\n

\u626b\u63cf\u6574\u4e2a\u7d22\u5f15<\/p>\n

\u540e\u8005：<\/p>\n

\u8986\u76d6\u7d22\u5f15<\/p>\n

19. Using index condition：\u7d22\u5f15\u6761\u4ef6\u4e0b\u63a8<\/h2>\n

CREATE<\/span> INDEX<\/span> idx_a_b_c
\nON<\/span> test(<\/span>a,<\/span> b,<\/span> c)<\/span>;<\/span><\/p>\n

\u6267\u884c：<\/p>\n

SELECT<\/span> *<\/span>
\nFROM<\/span> test
\nWHERE<\/span> a =<\/span> 1<\/span>
\n AND<\/span> b ><\/span> 10<\/span>
\n AND<\/span> c =<\/span> 3<\/span>;<\/span><\/p>\n

\u8fd9\u91cc：<\/p>\n

a = 1<\/p>\n

\u548c：<\/p>\n

b > 10<\/p>\n

\u53ef\u4ee5\u5e2e\u52a9\u5b9a\u4f4d\u7d22\u5f15\u8303\u56f4\u3002<\/p>\n

\u800c：<\/p>\n

c = 3<\/p>\n

\u867d\u7136\u901a\u5e38\u4e0d\u80fd\u7ee7\u7eed\u7f29\u5c0f\u8303\u56f4，\u4f46\u4ecd\u53ef\u80fd\u5728\u7d22\u5f15\u5c42\u8fdb\u884c\u8fc7\u6ee4\u3002<\/p>\n

\u5982\u679c MySQL \u4f7f\u7528\u4e86：<\/p>\n

Index Condition Pushdown<\/p>\n

\u6267\u884c\u8ba1\u5212\u4e2d\u53ef\u80fd\u51fa\u73b0：<\/p>\n

Using index condition<\/p>\n

\u53ef\u4ee5\u7406\u89e3\u6210：<\/p>\n

\u626b\u63cf\u7d22\u5f15\u8bb0\u5f55
\n \u2193
\n\u5148\u5224\u65ad\u7d22\u5f15\u4e2d\u80fd\u5224\u65ad\u7684\u6761\u4ef6
\n \u2193
\n\u7b26\u5408\u6761\u4ef6
\n \u2193
\n\u518d\u8bfb\u53d6\u5b8c\u6574\u884c<\/p>\n

\u8fd9\u6837\u53ef\u4ee5\u51cf\u5c11\u4e0d\u5fc5\u8981\u7684\u56de\u8868\u3002<\/p>\n

\u6240\u4ee5：<\/p>\n

Using index condition \u4e0d\u662f\u7d22\u5f15\u5931\u6548，\u800c\u662f MySQL \u5229\u7528\u7d22\u5f15\u4fe1\u606f\u8fdb\u884c\u63d0\u524d\u8fc7\u6ee4\u3002<\/p>\n

20. Using filesort：\u9700\u8981\u989d\u5916\u6392\u5e8f<\/h2>\n

\u5047\u8bbe：<\/p>\n

SELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> status<\/span> =<\/span> 1<\/span>
\nORDER<\/span> BY<\/span> amount DESC<\/span>;<\/span><\/p>\n

\u5982\u679c\u6ca1\u6709\u5408\u9002\u7d22\u5f15\u5e2e\u52a9\u6392\u5e8f，MySQL \u53ef\u80fd\u9700\u8981\u989d\u5916\u6267\u884c\u6392\u5e8f\u64cd\u4f5c\u3002<\/p>\n

\u8fd9\u65f6\u5019 Extra \u53ef\u80fd\u51fa\u73b0：<\/p>\n

Using filesort<\/p>\n

\u5f88\u591a\u4eba\u770b\u5230：<\/p>\n

filesort<\/p>\n

\u4f1a\u4ee5\u4e3a：<\/p>\n

\u4e00\u5b9a\u5728\u78c1\u76d8\u4e0a\u6392\u5e8f<\/p>\n

\u5176\u5b9e\u4e0d\u662f\u3002<\/p>\n

filesort \u662f MySQL \u5bf9\u989d\u5916\u6392\u5e8f\u64cd\u4f5c\u7684\u540d\u79f0，\u5e76\u4e0d\u4ee3\u8868\u4e00\u5b9a\u4f7f\u7528\u78c1\u76d8\u6587\u4ef6\u3002<\/p>\n

\u5b83\u53ef\u80fd\u5728\u5185\u5b58\u4e2d\u5b8c\u6210，\u4e5f\u53ef\u80fd\u5728\u6570\u636e\u91cf\u8f83\u5927\u65f6\u6d89\u53ca\u78c1\u76d8\u3002<\/p>\n

\u6240\u4ee5：<\/p>\n

Using filesort \u8868\u793a\u9700\u8981\u989d\u5916\u6392\u5e8f，\u4e0d\u7b49\u4e8e\u4e00\u5b9a\u53d1\u751f\u78c1\u76d8\u6392\u5e8f\u3002<\/p>\n

21. Using temporary：\u4f7f\u7528\u4e34\u65f6\u8868<\/h2>\n

\u67d0\u4e9b：<\/p>\n

GROUP<\/span> BY<\/span><\/p>\n

DISTINCT<\/span><\/p>\n

ORDER<\/span> BY<\/span><\/p>\n

\u590d\u6742\u67e5\u8be2<\/p>\n

\u53ef\u80fd\u9700\u8981\u4e34\u65f6\u8868\u8f85\u52a9\u5904\u7406\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

SELECT<\/span> status<\/span>,<\/span> COUNT<\/span>(<\/span>*<\/span>)<\/span>
\nFROM<\/span> orders
\nGROUP<\/span> BY<\/span> status<\/span>;<\/span><\/p>\n

\u5728\u67d0\u4e9b\u6267\u884c\u8ba1\u5212\u4e0b，\u53ef\u80fd\u770b\u5230：<\/p>\n

Using temporary<\/p>\n

\u8868\u793a MySQL \u4f7f\u7528\u4e86\u4e34\u65f6\u8868\u8fdb\u884c\u4e2d\u95f4\u7ed3\u679c\u5904\u7406\u3002<\/p>\n

\u4f46\u540c\u6837\u9700\u8981\u6ce8\u610f：<\/p>\n

Using temporary \u4e0d\u4ee3\u8868 SQL \u4e00\u5b9a\u5f88\u6162\u3002<\/p>\n

\u5982\u679c\u6570\u636e\u91cf\u5f88\u5c0f，\u4e34\u65f6\u8868\u53ef\u80fd\u6ca1\u6709\u660e\u663e\u95ee\u9898\u3002<\/p>\n

\u771f\u6b63\u9700\u8981\u5173\u6ce8\u7684\u662f：<\/p>\n

\u4e34\u65f6\u8868\u5904\u7406\u7684\u6570\u636e\u91cf<\/p>\n

\u662f\u5426\u53d1\u751f\u78c1\u76d8\u4e34\u65f6\u8868<\/p>\n

\u662f\u5426\u53ef\u4ee5\u901a\u8fc7\u7d22\u5f15\u4f18\u5316<\/p>\n

22. \u4e00\u4e2a\u6162 SQL \u600e\u4e48\u5206\u6790<\/h2>\n

\u73b0\u5728\u6765\u770b\u4e00\u4e2a\u6bd4\u8f83\u5178\u578b\u7684\u4f8b\u5b50\u3002<\/p>\n

\u5047\u8bbe\u8ba2\u5355\u8868\u6709：<\/p>\n

100 \u4e07\u6761\u6570\u636e<\/p>\n

\u5e76\u4e14\u5efa\u7acb：<\/p>\n

CREATE<\/span> INDEX<\/span> idx_create_time
\nON<\/span> orders(<\/span>create_time)<\/span>;<\/span><\/p>\n

\u73b0\u5728\u6267\u884c：<\/p>\n

SELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> YEAR<\/span>(<\/span>create_time)<\/span> =<\/span> 2026<\/span>;<\/span><\/p>\n

\u5047\u8bbe EXPLAIN \u663e\u793a：<\/p>\n

type = ALL<\/p>\n

possible_keys = NULL<\/p>\n

key = NULL<\/p>\n

rows = 1000000<\/p>\n

Extra = Using where<\/p>\n

\u8fd9\u91cc\u662f\u4e00\u4e2a\u793a\u610f\u6267\u884c\u8ba1\u5212，\u4e0d\u662f\u5b9e\u9645\u6570\u636e\u5e93\u6d4b\u8bd5\u7ed3\u679c\u3002<\/p>\n

\u6211\u4eec\u53ef\u4ee5\u8fd9\u6837\u5206\u6790\u3002<\/p>\n

\n

\u7b2c\u4e00\u6b65：\u770b type<\/h3>\n

type = ALL<\/p>\n

\u8bf4\u660e：<\/p>\n

\u5168\u8868\u626b\u63cf<\/p>\n

\n

\u7b2c\u4e8c\u6b65：\u770b key<\/h3>\n

key = NULL<\/p>\n

\u8bf4\u660e：<\/p>\n

\u6ca1\u6709\u9009\u62e9\u7d22\u5f15\u4f5c\u4e3a\u8bbf\u95ee\u8def\u5f84<\/p>\n

\n

\u7b2c\u4e09\u6b65：\u770b rows<\/h3>\n

rows = 1000000<\/p>\n

\u8bf4\u660e\u4f18\u5316\u5668\u9884\u8ba1：<\/p>\n

\u9700\u8981\u68c0\u67e5\u5927\u91cf\u8bb0\u5f55<\/p>\n

\n

\u7b2c\u56db\u6b65：\u770b SQL<\/h3>\n

YEAR<\/span>(<\/span>create_time)<\/span> =<\/span> 2026<\/span><\/p>\n

\u53d1\u73b0：<\/p>\n

\u5bf9\u7d22\u5f15\u5217\u4f7f\u7528\u4e86\u51fd\u6570<\/p>\n

\u666e\u901a create_time \u7d22\u5f15\u901a\u5e38\u65e0\u6cd5\u76f4\u63a5\u7528\u4e8e\u8fd9\u4e2a\u8868\u8fbe\u5f0f\u7684\u8303\u56f4\u5b9a\u4f4d\u3002<\/p>\n

\u4e8e\u662f\u53ef\u4ee5\u8003\u8651\u6539\u5199\u3002<\/p>\n

23. \u6539\u5199\u4ee5\u540e\u518d\u770b EXPLAIN<\/h2>\n

\u6539\u6210：<\/p>\n

SELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> create_time >=<\/span> '2026-01-01'<\/span>
\n AND<\/span> create_time <<\/span> '2027-01-01'<\/span>;<\/span><\/p>\n

\u5047\u8bbe\u65b0\u7684\u6267\u884c\u8ba1\u5212：<\/p>\n

type = range<\/p>\n

key = idx_create_time<\/p>\n

rows = 50000<\/p>\n

Extra = Using index condition<\/p>\n

\u540c\u6837，\u8fd9\u91cc\u53ea\u662f\u793a\u610f\u7ed3\u679c，\u5b9e\u9645\u8f93\u51fa\u53d6\u51b3\u4e8e\u6570\u636e\u548c MySQL \u7248\u672c\u3002<\/p>\n

\u73b0\u5728\u53ef\u4ee5\u7406\u89e3\u6210：<\/p>\n

\u539f\u6765：<\/p>\n

\u5168\u8868\u626b\u63cf
\n \u2193
\n\u9884\u8ba1\u68c0\u67e5 100 \u4e07\u884c<\/p>\n

\u6539\u6210：<\/p>\n

\u7d22\u5f15\u8303\u56f4\u626b\u63cf
\n \u2193
\n\u9884\u8ba1\u68c0\u67e5 5 \u4e07\u884c<\/p>\n

\u8bf4\u660e\u6539\u5199\u6709\u673a\u4f1a\u660e\u663e\u51cf\u5c11\u626b\u63cf\u91cf\u3002<\/p>\n

\u4f46\u6700\u540e\u8fd8\u9700\u8981\u9a8c\u8bc1：<\/p>\n

\u5b9e\u9645\u6267\u884c\u65f6\u95f4\u6709\u6ca1\u6709\u4e0b\u964d？<\/p>\n

\u56e0\u4e3a：<\/p>\n

EXPLAIN \u53ea\u662f\u5206\u6790\u5de5\u5177，\u771f\u6b63\u7684\u4f18\u5316\u7ed3\u679c\u8fd8\u9700\u8981\u901a\u8fc7\u5b9e\u9645\u6267\u884c\u6765\u9a8c\u8bc1\u3002<\/p>\n

24. EXPLAIN ANALYZE \u53c8\u662f\u4ec0\u4e48？<\/h2>\n

\u666e\u901a：<\/p>\n

EXPLAIN<\/span>
\nSELECT<\/span> .<\/span>.<\/span>.<\/span><\/p>\n

\u4e3b\u8981\u5c55\u793a：<\/p>\n

\u4f18\u5316\u5668\u9009\u62e9\u7684\u6267\u884c\u8ba1\u5212<\/p>\n

\u800c MySQL 8.0.18 \u53ca\u4ee5\u540e\u652f\u6301：<\/p>\n

EXPLAIN<\/span> ANALYZE<\/span>
\nSELECT<\/span> .<\/span>.<\/span>.<\/span><\/p>\n

\u5b83\u4f1a：<\/p>\n

\u5b9e\u9645\u6267\u884c\u67e5\u8be2<\/p>\n

\u5e76\u63d0\u4f9b\u5b9e\u9645\u6267\u884c\u4fe1\u606f，\u4f8b\u5982：<\/p>\n

\u5b9e\u9645\u8017\u65f6<\/p>\n

\u5b9e\u9645\u8bfb\u53d6\u884c\u6570<\/p>\n

\u5faa\u73af\u6b21\u6570<\/p>\n

\u56e0\u6b64\u53ef\u4ee5\u7528\u6765\u6bd4\u8f83：<\/p>\n

\u4f18\u5316\u5668\u4f30\u7b97<\/p>\n

\u548c：<\/p>\n

\u771f\u5b9e\u6267\u884c\u60c5\u51b5<\/p>\n

\u4f8b\u5982：<\/p>\n

EXPLAIN<\/span> ANALYZE<\/span>
\nSELECT<\/span> *<\/span>
\nFROM<\/span> orders
\nWHERE<\/span> user_id =<\/span> 10001<\/span>;<\/span><\/p>\n

\u8fd9\u5bf9\u4e8e\u5206\u6790：<\/p>\n

\u4e3a\u4ec0\u4e48\u4f18\u5316\u5668\u4f30\u7b97\u4e0d\u51c6？<\/p>\n

\u5230\u5e95\u54ea\u4e00\u6b65\u771f\u6b63\u8017\u65f6？<\/p>\n

\u975e\u5e38\u6709\u5e2e\u52a9\u3002<\/p>\n

\u4e0d\u8fc7\u8981\u6ce8\u610f：<\/p>\n

EXPLAIN ANALYZE \u4f1a\u5b9e\u9645\u6267\u884c\u8bed\u53e5，\u4e0d\u8981\u628a\u5b83\u5f53\u6210\u5b8c\u5168\u65e0\u526f\u4f5c\u7528\u7684\u666e\u901a EXPLAIN\u3002<\/p>\n

\u5c24\u5176\u5728\u751f\u4ea7\u73af\u5883\u4e2d，\u9700\u8981\u6ce8\u610f\u67e5\u8be2\u6210\u672c\u548c\u6267\u884c\u5f71\u54cd\u3002<\/p>\n

25. EXPLAIN \u8fd8\u6709\u54ea\u4e9b\u503c\u5f97\u77e5\u9053\u7684\u5f62\u5f0f？<\/h2>\n

\u9664\u4e86\u666e\u901a\u8868\u683c\u5f62\u5f0f：<\/p>\n

EXPLAIN<\/span>
\nSELECT<\/span> .<\/span>.<\/span>.<\/span><\/p>\n

MySQL \u8fd8\u652f\u6301：<\/p>\n

EXPLAIN<\/span> FORMAT=<\/span>JSON
\nSELECT<\/span> .<\/span>.<\/span>.<\/span><\/p>\n

JSON \u683c\u5f0f\u4f1a\u63d0\u4f9b\u66f4\u52a0\u8be6\u7ec6\u7684\u6267\u884c\u8ba1\u5212\u4fe1\u606f\u3002<\/p>\n

\u4f8b\u5982：<\/p>\n

\u8bbf\u95ee\u8def\u5f84<\/p>\n

\u6210\u672c\u4f30\u7b97<\/p>\n

\u4f7f\u7528\u7684\u7d22\u5f15<\/p>\n

\u8fc7\u6ee4\u6761\u4ef6<\/p>\n

\u6392\u5e8f\u4fe1\u606f<\/p>\n

\u5bf9\u4e8e\u5165\u95e8\u9636\u6bb5：<\/p>\n

\u666e\u901a EXPLAIN<\/p>\n

\u5df2\u7ecf\u8db3\u591f\u3002<\/p>\n

\u7b49\u4ee5\u540e\u5206\u6790\u590d\u6742 JOIN\u3001\u5b50\u67e5\u8be2\u6216\u4f18\u5316\u5668\u6210\u672c\u65f6，\u518d\u6df1\u5165：<\/p>\n

EXPLAIN FORMAT=JSON<\/p>\n

\u4f1a\u66f4\u52a0\u5408\u9002\u3002<\/p>\n

26. \u5b9e\u9645\u5f00\u53d1\u4e2d\u600e\u4e48\u770b EXPLAIN？<\/h2>\n

\u6211\u5efa\u8bae\u6309\u7167\u8fd9\u4e2a\u987a\u5e8f：<\/p>\n

SQL \u5f88\u6162
\n \u2193
\n\u5148\u770b type
\n \u2193
\n\u662f\u5168\u8868\u626b\u63cf\u8fd8\u662f\u7d22\u5f15\u8bbf\u95ee？
\n \u2193
\n\u770b key
\n \u2193
\n\u5b9e\u9645\u7528\u4e86\u54ea\u4e2a\u7d22\u5f15？
\n \u2193
\n\u770b rows
\n \u2193
\n\u9884\u8ba1\u626b\u63cf\u591a\u5c11\u884c？
\n \u2193
\n\u770b Extra
\n \u2193
\n\u662f\u5426\u6709\u989d\u5916\u6392\u5e8f\u3001\u4e34\u65f6\u8868\u3001\u7d22\u5f15\u6761\u4ef6\u4e0b\u63a8？
\n \u2193
\n\u7ed3\u5408 SQL \u548c\u7d22\u5f15\u7ed3\u6784\u5206\u6790<\/p>\n

\u4e0d\u8981\u53ea\u76ef\u7740：<\/p>\n

key<\/p>\n

\u56e0\u4e3a：<\/p>\n

\u7528\u4e86\u7d22\u5f15<\/p>\n

\u4e0d\u4ee3\u8868：<\/p>\n

\u67e5\u8be2\u4e00\u5b9a\u5feb<\/p>\n

\u4e5f\u4e0d\u8981\u53ea\u76ef\u7740：<\/p>\n

type = ALL<\/p>\n

\u56e0\u4e3a：<\/p>\n

\u5168\u8868\u626b\u63cf<\/p>\n

\u4e0d\u4ee3\u8868：<\/p>\n

\u4e00\u5b9a\u9700\u8981\u4f18\u5316<\/p>\n

\u771f\u6b63\u8981\u7ed3\u5408：<\/p>\n

\u6570\u636e\u91cf<\/p>\n

\u8fc7\u6ee4\u6bd4\u4f8b<\/p>\n

\u56de\u8868\u6210\u672c<\/p>\n

\u6392\u5e8f\u6210\u672c<\/p>\n

\u5b9e\u9645\u6267\u884c\u65f6\u95f4<\/p>\n

\u4e00\u8d77\u5224\u65ad\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

\u4e0a\u4e00\u7bc7\u6211\u4eec\u8bb2\u4e86 MySQL \u7d22\u5f15\u4e3a\u4ec0\u4e48\u53ef\u80fd\u5931\u6548\u3002
\n\u4f8b\u5982：
\nSELECT *
\nFROM user
\nWHERE YEAR(create_time) 2026;\u6216\u8005：
\nSELECT *
\nFROM user
\nWHERE name LIKE %\u5f20;\u6211\u4eec\u77e5\u9053，\u8fd9\u4e9b\u5199\u6cd5\u901a\u5e38\u4e0d\u5229\u4e8e\u666e\u901a BTree \u7d22\u5f15\u8fdb\u884c\u9ad8\u6548\u5b9a\u4f4d\u3002
\n\u4f46\u5b9e\u9645\u5f00\u53d1\u4e2d，\u4e0d\u80fd\u53ea\u9760\u7ecf\u9a8c\u5224\u65ad：\u8fd9\u4e2a SQL \u5e94\u8be5\u8d70\u7d22\u5f15\u5427？\u56e0\u4e3a MySQL \u4f18\u5316\u5668\u6700\u7ec8\u53ef<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[11653,114,100],"topic":[],"class_list":["post-103207","post","type-post","status-publish","format-standard","hentry","category-server","tag-11653","tag-mysql","tag-100"],"yoast_head":"\nMySQL EXPLAIN \u600e\u4e48\u770b\uff1f\u4e00\u6761\u6162 SQL \u5230\u5e95\u6162\u5728\u54ea\uff1f - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.wsisp.com\/helps\/103207.html\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"MySQL EXPLAIN \u600e\u4e48\u770b\uff1f\u4e00\u6761\u6162 SQL \u5230\u5e95\u6162\u5728\u54ea\uff1f - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"og:description\" content=\"\u4e0a\u4e00\u7bc7\u6211\u4eec\u8bb2\u4e86 MySQL \u7d22\u5f15\u4e3a\u4ec0\u4e48\u53ef\u80fd\u5931\u6548\u3002 \u4f8b\u5982： SELECT * FROM user WHERE YEAR(create_time) 2026;\u6216\u8005： SELECT * FROM user WHERE name LIKE %\u5f20;\u6211\u4eec\u77e5\u9053，\u8fd9\u4e9b\u5199\u6cd5\u901a\u5e38\u4e0d\u5229\u4e8e\u666e\u901a BTree \u7d22\u5f15\u8fdb\u884c\u9ad8\u6548\u5b9a\u4f4d\u3002 \u4f46\u5b9e\u9645\u5f00\u53d1\u4e2d，\u4e0d\u80fd\u53ea\u9760\u7ecf\u9a8c\u5224\u65ad：\u8fd9\u4e2a SQL \u5e94\u8be5\u8d70\u7d22\u5f15\u5427？\u56e0\u4e3a MySQL \u4f18\u5316\u5668\u6700\u7ec8\u53ef\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.wsisp.com\/helps\/103207.html\" \/>\n<meta property=\"og:site_name\" content=\"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\" \/>\n<meta property=\"article:published_time\" content=\"2026-09-09T18:25:18+00:00\" \/>\n<meta name=\"author\" content=\"admin\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u4f5c\u8005\" \/>\n\t<meta name=\"twitter:data1\" content=\"admin\" \/>\n\t<meta name=\"twitter:label2\" content=\"\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4\" \/>\n\t<meta name=\"twitter:data2\" content=\"6 \u5206\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/103207.html\",\"url\":\"https:\/\/www.wsisp.com\/helps\/103207.html\",\"name\":\"MySQL EXPLAIN \u600e\u4e48\u770b\uff1f\u4e00\u6761\u6162 SQL \u5230\u5e95\u6162\u5728\u54ea\uff1f - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\",\"isPartOf\":{\"@id\":\"https:\/\/www.wsisp.com\/helps\/#website\"},\"datePublished\":\"2026-09-09T18:25:18+00:00\",\"dateModified\":\"2026-09-09T18:25:18+00:00\",\"author\":{\"@id\":\"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41\"},\"breadcrumb\":{\"@id\":\"https:\/\/www.wsisp.com\/helps\/103207.html#breadcrumb\"},\"inLanguage\":\"zh-Hans\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.wsisp.com\/helps\/103207.html\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/103207.html#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"\u9996\u9875\",\"item\":\"https:\/\/www.wsisp.com\/helps\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"MySQL EXPLAIN \u600e\u4e48\u770b\uff1f\u4e00\u6761\u6162 SQL \u5230\u5e95\u6162\u5728\u54ea\uff1f\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/#website\",\"url\":\"https:\/\/www.wsisp.com\/helps\/\",\"name\":\"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3\",\"description\":\"\u9999\u6e2f\u670d\u52a1\u5668_\u9999\u6e2f\u4e91\u670d\u52a1\u5668\u8d44\u8baf_\u670d\u52a1\u5668\u5e2e\u52a9\u6587\u6863_\u670d\u52a1\u5668\u6559\u7a0b\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.wsisp.com\/helps\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"zh-Hans\"},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41\",\"name\":\"admin\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"zh-Hans\",\"@id\":\"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery\",\"contentUrl\":\"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery\",\"caption\":\"admin\"},\"sameAs\":[\"http:\/\/wp.wsisp.com\"],\"url\":\"https:\/\/www.wsisp.com\/helps\/author\/admin\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"MySQL EXPLAIN \u600e\u4e48\u770b\uff1f\u4e00\u6761\u6162 SQL \u5230\u5e95\u6162\u5728\u54ea\uff1f - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.wsisp.com\/helps\/103207.html","og_locale":"zh_CN","og_type":"article","og_title":"MySQL EXPLAIN \u600e\u4e48\u770b\uff1f\u4e00\u6761\u6162 SQL \u5230\u5e95\u6162\u5728\u54ea\uff1f - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","og_description":"\u4e0a\u4e00\u7bc7\u6211\u4eec\u8bb2\u4e86 MySQL \u7d22\u5f15\u4e3a\u4ec0\u4e48\u53ef\u80fd\u5931\u6548\u3002 \u4f8b\u5982： SELECT * FROM user WHERE YEAR(create_time) 2026;\u6216\u8005： SELECT * FROM user WHERE name LIKE %\u5f20;\u6211\u4eec\u77e5\u9053，\u8fd9\u4e9b\u5199\u6cd5\u901a\u5e38\u4e0d\u5229\u4e8e\u666e\u901a BTree \u7d22\u5f15\u8fdb\u884c\u9ad8\u6548\u5b9a\u4f4d\u3002 \u4f46\u5b9e\u9645\u5f00\u53d1\u4e2d，\u4e0d\u80fd\u53ea\u9760\u7ecf\u9a8c\u5224\u65ad：\u8fd9\u4e2a SQL \u5e94\u8be5\u8d70\u7d22\u5f15\u5427？\u56e0\u4e3a MySQL \u4f18\u5316\u5668\u6700\u7ec8\u53ef","og_url":"https:\/\/www.wsisp.com\/helps\/103207.html","og_site_name":"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","article_published_time":"2026-09-09T18:25:18+00:00","author":"admin","twitter_card":"summary_large_image","twitter_misc":{"\u4f5c\u8005":"admin","\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4":"6 \u5206"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/www.wsisp.com\/helps\/103207.html","url":"https:\/\/www.wsisp.com\/helps\/103207.html","name":"MySQL EXPLAIN \u600e\u4e48\u770b\uff1f\u4e00\u6761\u6162 SQL \u5230\u5e95\u6162\u5728\u54ea\uff1f - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","isPartOf":{"@id":"https:\/\/www.wsisp.com\/helps\/#website"},"datePublished":"2026-09-09T18:25:18+00:00","dateModified":"2026-09-09T18:25:18+00:00","author":{"@id":"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41"},"breadcrumb":{"@id":"https:\/\/www.wsisp.com\/helps\/103207.html#breadcrumb"},"inLanguage":"zh-Hans","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.wsisp.com\/helps\/103207.html"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.wsisp.com\/helps\/103207.html#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"\u9996\u9875","item":"https:\/\/www.wsisp.com\/helps"},{"@type":"ListItem","position":2,"name":"MySQL EXPLAIN \u600e\u4e48\u770b\uff1f\u4e00\u6761\u6162 SQL \u5230\u5e95\u6162\u5728\u54ea\uff1f"}]},{"@type":"WebSite","@id":"https:\/\/www.wsisp.com\/helps\/#website","url":"https:\/\/www.wsisp.com\/helps\/","name":"\u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3","description":"\u9999\u6e2f\u670d\u52a1\u5668_\u9999\u6e2f\u4e91\u670d\u52a1\u5668\u8d44\u8baf_\u670d\u52a1\u5668\u5e2e\u52a9\u6587\u6863_\u670d\u52a1\u5668\u6559\u7a0b","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.wsisp.com\/helps\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"zh-Hans"},{"@type":"Person","@id":"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/358e386c577a3ab51c4493330a20ad41","name":"admin","image":{"@type":"ImageObject","inLanguage":"zh-Hans","@id":"https:\/\/www.wsisp.com\/helps\/#\/schema\/person\/image\/","url":"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery","contentUrl":"https:\/\/gravatar.wp-china-yes.net\/avatar\/?s=96&d=mystery","caption":"admin"},"sameAs":["http:\/\/wp.wsisp.com"],"url":"https:\/\/www.wsisp.com\/helps\/author\/admin"}]}},"_links":{"self":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/posts\/103207","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/comments?post=103207"}],"version-history":[{"count":0,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/posts\/103207\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/media?parent=103207"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/categories?post=103207"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/tags?post=103207"},{"taxonomy":"topic","embeddable":true,"href":"https:\/\/www.wsisp.com\/helps\/wp-json\/wp\/v2\/topic?post=103207"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}