{"id":87559,"date":"2020-05-09T19:00:14","date_gmt":"2020-05-09T11:00:14","guid":{"rendered":"http:\/\/4563.org\/?p=87559"},"modified":"2020-05-09T19:00:14","modified_gmt":"2020-05-09T11:00:14","slug":"%e5%85%b3%e4%ba%8e%e8%a6%86%e7%9b%96%e7%b4%a2%e5%bc%95%e7%9a%84%e9%97%ae%e9%a2%98","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=87559","title":{"rendered":"\u5173\u4e8e\u8986\u76d6\u7d22\u5f15\u7684\u95ee\u9898"},"content":{"rendered":"
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\u5173\u4e8e\u8986\u76d6\u7d22\u5f15\u7684\u95ee\u9898 <\/h1>\n

<\/p>\n

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\u8cc7\u6df1\u5927\u4f6c : qmzhixu <\/span> <\/i> 9<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
<\/p>\n

\u6700\u8fd1\u590d\u4e60\u770b\u5230\u8986\u76d6\u7d22\u5f15\u7684\u6982\u5ff5\uff0c\u6709\u4e00\u4e2a Innodb \u8868 user(id pk,age)\uff0cid \u4e3a\u4e3b\u952e\uff0c\u4f7f\u7528 EXPLAIN SELECT id from user where id=1; \u53ef\u4ee5\u53d1\u73b0\u4f7f\u7528\u5230\u4e86\u8986\u76d6\u7d22\u5f15\uff0c\u4f46\u662f\u6267\u884c EXPLAIN SELECT age from user where id=1; \u65f6\u53d1\u73b0 \u5e76\u672a\u4f7f\u7528\u5230\u8986\u76d6\u7d22\u5f15\uff0c\u67e5\u7684\u8d44\u6599\u90fd\u8bf4 InnoDB \u805a\u96c6\u7d22\u5f15\u7684\u53f6\u5b50\u8282\u70b9\u5b58\u50a8\u884c\u8bb0\u5f55\u5e94\u8be5\u5305\u542b\u6709 age \u8fd9\u4e2a\u5b57\u6bb5\u7684\uff0c\u4f46\u662f\u8fd9\u884c\u67e5\u8be2\u5e76\u6ca1\u6709\u7528\u5230\u8986\u76d6\u7d22\u5f15\uff0c\u662f\u4e0d\u662f\u6211\u7406\u89e3\u6709\u8bef\u4e86\u3002<\/p>\n<\/p><\/div>\n

\u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (13<\/span>) <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : snappyone <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u4f60\u8fd9\u4e2a\u8868\u4e00\u5171\u5c31 2 \u5217\u8fd8\u5f04\u5565\u8986\u76d6\u7d22\u5f15 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : Jacky23333 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @snappyone \u8001\u5b9e\u4eba <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : qmzhixu <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @snappyone \u6211\u662f\u60f3\u641e\u61c2\u8fd9\u4e2a\u539f\u7406\uff0c\u4e24\u4e2a\u5217\u53ea\u662f\u65b9\u4fbf\u770b\u3002\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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    \u8cc7\u6df1\u5927\u4f6c : Jacky23333 <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u805a\u96c6\u7d22\u5f15\u91cc\u9762\u5305\u542b age \u5b57\u6bb5\u8ddf age \u6709\u6ca1\u6709\u52a0\u7d22\u5f15\u5b8c\u5168\u6ca1\u6709\u5173\u7cfb\uff0c\u4f60\u8bf4\u7684\u805a\u96c6\u7d22\u5f15\u5176\u5b9e\u53ea\u5305\u542b\u4e86 id \u5b57\u6bb5\uff0c\u4f60\u7684 age \u5b57\u6bb5\u90fd\u6ca1\u6709\u7d22\u5f15\u90a3\u81ea\u7136\u4e0d\u4f1a\u6709\u7d22\u5f15\u8986\u76d6 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : qmzhixu <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @Jacky23333 \u55ef\uff0c\u56e0\u4e3a\u53ef\u4ee5\u7528\u5230 id \u627e\u5230\u53f6\u8282\u70b9\u91cc\u9762\u7684 age\uff0c\u6309\u7406\u4e5f\u6ca1\u6709\u56de\u8868\u68c0\u7d22\u4e86\uff0c\u6240\u4ee5\u662f\u4e0d\u662f\u8986\u76d6\u7d22\u5f15\u90fd\u6ca1\u533a\u522b\u4e86 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \n
    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : qmzhixu <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @Jacky23333 \u53ea\u662f\u6267\u884c\u8ba1\u5212\u91cc\u9762\u7684 extra \u5b57\u6bb5\u663e\u793a\u7684\u662f\u4e0d\u662f Using index \u800c\u5df2 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : imtemp <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u8986\u76d6\u7d22\u5f15\u7684\u6982\u5ff5\u7406\u89e3\u6709\u5dee\u5f02\uff0c\u770b\u770b\u8fd9\u9898
    https:\/\/segmentfault.com\/q\/1010000018998466 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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    \u8cc7\u6df1\u5927\u4f6c : imtemp <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u5b98\u65b9\u6587\u6863\u91cc\u9762\u5bf9\u8986\u76d6\u7d22\u5f15\u7684\u5b9a\u4e49\uff1a https:\/\/dev.mysql.com\/doc\/refman\/8.0\/en\/glossary.html#glos_covering_index <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u8cc7\u6df1\u5927\u4f6c : qumingkunnan <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u7d22\u5f15\u8986\u76d6\u662f\u8bf4\u901a\u8fc7\u7d22\u5f15\u67e5\u6570\u636e\uff0c\u7136\u540e\u67e5\u7684\u6570\u636e\u521a\u597d\u88ab\u7d22\u5f15\u5305\u542b\u4e86\u7684\u610f\u601d\u5427\uff1f\u90a3\u4e48\u6211\u7406\u89e3\u4f60\u53ef\u4ee5\u518d\u52a0\u4e2a\u5b57\u6bb5 sex(\u8fd9\u4e2a\u5b57\u6bb5\u53ef\u80fd\u52a0\u7d22\u5f15\u4e0d\u592a\u5408\u9002\uff0c\u53ea\u4e3e\u4f8b\u7528)\uff0c\u7136\u540e\u5efa\u7acb\u4e00\u4e2a age,sex \u7684\u7d22\u5f15\uff0c\u7136\u540e\u67e5\u8be2 age,sex \u5b57\u6bb5\uff0c\u6761\u4ef6\u7528 age \u6216\u8005 age,sex \u3002\u5e94\u8be5\u662f\u6ee1\u8db3\u7d22\u5f15\u8986\u76d6\u7684\uff0c\u9a8c\u8bc1\u4e0b <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : qmzhixu <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @qumingkunnan \u8fd9\u79cd\u80af\u5b9a\u662f\u53ef\u4ee5\u7684\uff0c\u6211\u6307\u7684\u662f\u5728\u805a\u96c6\u7d22\u5f15\u53f6\u8282\u70b9\u6570\u636e\uff0c\u4e0d\u662f\u5176\u4ed6\u7684\u7d22\u5f15 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
    \u8cc7\u6df1\u5927\u4f6c : qumingkunnan <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    @qmzhixu \u63a5\u6211\u4e0a\u6761\u56de\u590d\uff0c\u805a\u7c07\u7d22\u5f15\u901a\u5e38\u53ea\u662f\u4e3b\u952e\u505a\u7d22\u5f15\uff0c\u4f60\u8bf4\u7684\u53f6\u5b50\u8282\u70b9\u662f\u805a\u7c07\u7d22\u5f15\u8fd9\u4e2a\u5b58\u50a8\u7ed3\u6784\u7684\u4e00\u90e8\u5206\uff0c\u4e0d\u662f\u7d22\u5f15\u3002\u805a\u7c07\u7d22\u5f15\u662f innodb \u4e2d\u8868\u7684\u5b58\u50a8\u5f62\u5f0f\uff0c\u800c\u4e0d\u4ec5\u4ec5\u662f\u7d22\u5f15\u3002 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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    \u8cc7\u6df1\u5927\u4f6c : gmhdbjd <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u6ca1\u8d5a\u4f60\u7684 id \u4e0d\u662f\u771f\u7684\u805a\u96c6\u7d22\u5f15 <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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    \u8cc7\u6df1\u5927\u4f6c : Aresxue <\/span> <\/div>\n
    <\/i> <\/span> <\/div>\n<\/p><\/div>\n
    \u662f\u5426\u4f7f\u7528\u8986\u76d6\u7d22\u5f15\u548c age \u4e0a\u9762\u6709\u6ca1\u6709\u7d22\u5f15\u6709\u76f4\u63a5\u5173\u7cfb, \u6ca1\u6709\u7d22\u5f15\u7684\u8bdd\u81ea\u7136\u4e0d\u4f1a\u8d70\u8986\u76d6\u7d22\u5f15, \u800c\u4e14\u4f60\u8fd9\u4e2a age \u8fd8\u5f88\u6709\u53ef\u80fd\u533a\u5206\u5ea6 cardinality \u4e0d\u591f\u6216\u8005\u6570\u636e\u91cf\u5f88\u5c0f\uff0cCBO \u53d1\u73b0\u5168\u8868\u626b\u63cf\u7684 cost \u53cd\u800c\u6bd4\u8f83\u5c0f\uff0c\u90a3\u5c31\u76f4\u63a5\u626b\u5168\u8868\u55bd <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"

    \u5173\u4e8e\u8986\u76d6\u7d22\u5f15\u7684\u95ee\u9898 \u8cc7\u6df1\u5927\u4f6c : …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/87559"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=87559"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/87559\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=87559"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=87559"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=87559"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}