{"id":10006421,"date":"2022-09-06T21:43:23","date_gmt":"2022-09-06T13:43:23","guid":{"rendered":"https:\/\/ityet.com\/?p=10006421"},"modified":"2022-09-06T21:43:23","modified_gmt":"2022-09-06T13:43:23","slug":"%e9%aa%8c%e8%af%81%e4%b8%80%e4%b8%aa%e5%b0%8f%e5%b0%8f%e7%9a%84%e9%97%ae%e9%a2%98","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10006421","title":{"rendered":"\u9a8c\u8bc1\u4e00\u4e2a\u5c0f\u5c0f\u7684\u95ee\u9898"},"content":{"rendered":"<p>\u5728\u4e4b\u524d\u7684\u6587\u7ae0\u63d0\u5230\u8fc7\u4e00\u4e2a\u95ee\u9898\uff0c\u800c\u4e14\u7f51\u4e0a\u5f88\u591a\u6587\u7ae0\u4e5f\u662f\u8fd9\u4e48\u8bf4\u7684\uff0c\u524d\u51e0\u5929\u6709\u4eba\u5bf9\u8fd9\u4e2a\u95ee\u9898\u63d0\u51fa\u4e86\u4e00\u70b9\u4e0d\u540c\u7684\u610f\u89c1\uff0c\u62b1\u7740\u8c28\u614e\u7684\u6001\u5ea6\u505a\u4e86\u4e00\u4e2a\u6d4b\u8bd5\u3002<\/p>\n<p>\u95ee\u9898\u662f\u8fd9\u6837\u7684\uff1aCOMPACT\u683c\u5f0f\u4e0b\uff0cNULL\u503c\u5217\u8868\u662f\u5426\u4e00\u5b9a\u4f1a\u5360\u7528\u4e00\u4e2a\u5b57\u8282\u7684\u7a7a\u95f4\uff1f<\/p>\n<p>\u5bf9\u4e8e\u8fd9\u4e2a\u95ee\u9898\uff0c\u6211\u7684\u56de\u7b54\u548c\u7f51\u4e0a\u5f88\u591a\u56de\u7b54\u662f\u4e00\u6837\u7684\uff0c\u5982\u679c\u90fd\u662fNOT NULL\u5c31\u4e0d\u4f1a\u6709NULL\u503c\u5217\u8868\uff0c\u6240\u4ee5\u4e0d\u4f1a\u5360\u7528\uff0c\u53cd\u4e4b\u5219\u4f1a\u5360\u7528\u3002<\/p>\n<p>\u4eca\u5929\uff0c\u5c31\u5bf9\u8fd9\u4e2a\u95ee\u9898\u505a\u4e00\u4e2a\u9a8c\u8bc1\u3002<\/p>\n<h2>\u5b58\u50a8\u7a7a\u95f4<\/h2>\n<p>\u5148\u56de\u987e\u4e00\u4e0b\u4e4b\u524d\u7684\u77e5\u8bc6\u3002<\/p>\n<p>\u6570\u636e\u5e93\u4e2d\u7684\u4e00\u884c\u8bb0\u5f55\u5728\u6700\u7ec8\u78c1\u76d8\u6587\u4ef6\u4e2d\u4e5f\u662f\u4ee5\u884c\u7684\u65b9\u5f0f\u6765\u5b58\u50a8\u7684\uff0c\u5bf9\u4e8eInnoDB\u6765\u8bf4\uff0c\u67094\u79cd\u884c\u5b58\u50a8\u683c\u5f0f\uff1a<code>REDUNDANT<\/code>\u3001 <code>COMPACT<\/code>\u3001 <code>DYNAMIC<\/code> \u548c <code>COMPRESSED<\/code>\u3002<\/p>\n<p>InnoDB\u7684\u9ed8\u8ba4\u884c\u5b58\u50a8\u683c\u5f0f\u662f<code>COMPACT<\/code>\uff0c\u5b58\u50a8\u683c\u5f0f\u5982\u4e0b\u6240\u793a\uff0c\u865a\u7ebf\u90e8\u5206\u4ee3\u8868\u53ef\u80fd\u4e0d\u4e00\u5b9a\u4f1a\u5b58\u5728\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042440857\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u53d8\u957f\u5b57\u6bb5\u957f\u5ea6\u5217\u8868\uff1a\u6709\u591a\u4e2a\u5b57\u6bb5\u5219\u4ee5\u9006\u5e8f\u5b58\u50a8\uff0c\u6211\u4eec\u53ea\u6709\u4e00\u4e2a\u5b57\u6bb5\u6240\u6709\u4e0d\u8003\u8651\u90a3\u4e48\u591a\uff0c\u5b58\u50a8\u683c\u5f0f\u662f16\u8fdb\u5236\uff0c\u5982\u679c\u6ca1\u6709\u53d8\u957f\u5b57\u6bb5\u5c31\u4e0d\u9700\u8981\u8fd9\u4e00\u90e8\u5206\u4e86\u3002<\/p>\n<p>NULL\u503c\u5217\u8868\uff1a\u7528\u6765\u5b58\u50a8\u6211\u4eec\u8bb0\u5f55\u4e2d\u503c\u4e3aNULL\u7684\u60c5\u51b5\uff0c\u5982\u679c\u5b58\u5728\u591a\u4e2aNULL\u503c\u90a3\u4e48\u4e5f\u662f\u9006\u5e8f\u5b58\u50a8\uff0c\u5e76\u4e14\u5fc5\u987b\u662f8bit\u7684\u6574\u6570\u500d\uff0c\u5982\u679c\u4e0d\u591f8bit\uff0c\u5219\u9ad8\u4f4d\u88650\u30021\u4ee3\u8868\u662fNULL\uff0c0\u4ee3\u8868\u4e0d\u662fNULL\u3002\u5982\u679c\u90fd\u662fNOT NULL\u90a3\u4e48\u8fd9\u4e2a\u5c31\u5b58\u5728\u4e86\uff0c\u6bcf\u591a8\u4e2aNULL\u4f1a\u591a\u5360\u7528\u4e00\u4e2a\u5b57\u8282\u7684\u7a7a\u95f4\u3002<\/p>\n<p>ROW_ID\uff1a\u4e00\u884c\u8bb0\u5f55\u7684\u552f\u4e00\u6807\u5fd7\uff0c\u6ca1\u6709\u6307\u5b9a\u4e3b\u952e\u7684\u65f6\u5019\u81ea\u52a8\u751f\u6210\u7684ROW_ID\u4f5c\u4e3a\u4e3b\u952e\u3002<\/p>\n<p>TRX_ID\uff1a\u4e8b\u52a1ID\u3002<\/p>\n<p>ROLL_PRT\uff1a\u56de\u6eda\u6307\u9488\u3002<\/p>\n<p>\u6700\u540e\u5c31\u662f\u6bcf\u5217\u7684\u503c\u3002<\/p>\n<p>\u4e3a\u4e86\u8bf4\u660e\u6e05\u695a\u8fd9\u4e2a\u5b58\u50a8\u683c\u5f0f\u7684\u95ee\u9898\uff0c\u6211\u5f04\u5f20\u8868\u6765\u6d4b\u8bd5\uff0c\u8fd9\u5f20\u8868\u53ea\u6709<code>c1<\/code>\u5b57\u6bb5\u662fNOT NULL\uff0c\u5176\u4ed6\u90fd\u662f\u53ef\u4ee5\u4e3aNULL\u7684\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042440858\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p><strong>\u53ef\u53d8\u5b57\u6bb5\u957f\u5ea6\u5217\u8868<\/strong>\uff1a<code>c1<\/code>\u548c<code>c3<\/code>\u5b57\u6bb5\u503c\u957f\u5ea6\u5206\u522b\u4e3a1\u548c2\uff0c\u6240\u4ee5\u957f\u5ea6\u8f6c\u6362\u4e3a16\u8fdb\u5236\u662f<code>0x01 0x02<\/code>\uff0c\u9006\u5e8f\u4e4b\u540e\u5c31\u662f<code>0x02 0x01<\/code>\u3002<\/p>\n<p><strong>NULL\u503c\u5217\u8868<\/strong>\uff1a\u56e0\u4e3a\u5b58\u5728\u5141\u8bb8\u4e3aNULL\u7684\u5217\uff0c\u6240\u4ee5<code>c2,c3,c4<\/code>\u5206\u522b\u4e3a010\uff0c\u9006\u5e8f\u4e4b\u540e\u8fd8\u662f\u4e00\u6837\uff0c\u540c\u65f6\u9ad8\u4f4d\u88650\u6ee18\u4f4d\uff0c\u7ed3\u679c\u662f<code>00000010<\/code>\u3002<\/p>\n<p>\u5176\u4ed6\u5b57\u6bb5\u6211\u4eec\u6682\u65f6\u4e0d\u7ba1\u4ed6\uff0c\u6700\u540e\u7b2c\u4e00\u6761\u8bb0\u5f55\u7684\u7ed3\u679c\u5c31\u662f\uff0c\u5f53\u7136\u8fd9\u91cc\u6211\u4eec\u5c31\u4e0d\u8003\u8651\u7f16\u7801\u4e4b\u540e\u7684\u7ed3\u679c\u4e86\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042440859\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u8fd9\u6837\u5c31\u662f\u4e00\u4e2a\u5b8c\u6574\u7684\u6570\u636e\u884c\u6570\u636e\u7684\u683c\u5f0f\uff0c\u53cd\u4e4b\uff0c\u5982\u679c\u6211\u4eec\u628a\u6240\u6709\u5b57\u6bb5\u90fd\u8bbe\u7f6e\u4e3aNOT NULL\uff0c\u5e76\u4e14\u63d2\u5165\u4e00\u6761\u6570\u636e<code>a,bb,ccc,dddd<\/code>\u7684\u8bdd\uff0c\u5b58\u50a8\u683c\u5f0f\u5e94\u8be5\u8fd9\u6837\uff1a<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042440860\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<h2>\u6d4b\u8bd5<\/h2>\n<p>\u8fd9\u91cc\u5b58\u5728\u4e00\u70b9\u70b9\u5c0f\u95ee\u9898\uff0c\u9996\u5148\u6211\u770b\u5230\u4e86\u963f\u91cc\u7684\u6570\u636e\u5e93\u6708\u62a5\u4e2d\u7684\u6d4b\u8bd5\u548c\u63cf\u8ff0\u3002<\/p>\n<blockquote><p>\u4ece\u8fd9\u6bb5\u4ee3\u7801\u770b\u51fa\u4e4b\u524d\u7684\u731c\u60f3\uff0c\u4e5f\u5c31\u662f\u5e76\u4e0d\u662fNull\u6807\u5fd7\u4f4d\u53ea\u56fa\u5b9a\u5360\u75281\u4e2a\u5b57\u8282==\uff0c\u800c\u662f\u4ee58\u4e3a\u5355\u4f4d\uff0c\u6ee18\u4e2anull\u5b57\u6bb5\u5c31\u591a1\u4e2a\u5b57\u8282\uff0c\u4e0d\u6ee18\u4e2a\u4e5f\u5360\u75281\u4e2a\u5b57\u8282\uff0c\u9ad8\u4f4d\u75280\u8865\u9f50<\/p><\/blockquote>\n<p>\u4ed6\u7684\u610f\u601d\u662f\u65e0\u8bba\u5982\u4f55\u90fd\u4f1a\u5360\u7528\u4e00\u4e2a\u5b57\u8282\uff0c\u4f46\u662f\u770b\u4e86\u4ed6\u7684\u6d4b\u8bd5\uff0c\u53d1\u73b0\u4ed6\u7684\u8868\u662f\u5141\u8bb8NULL\u7684\uff0c\u6240\u4ee5\u4ed6\u7684\u8fd9\u4e2a\u6d4b\u8bd5\u65e0\u6cd5\u8bf4\u660e\u6211\u4eec\u8981\u9a8c\u8bc1\u7684\u95ee\u9898\u3002<\/p>\n<p>\u6309\u7167\u7f51\u4e0a\u5927\u4f6c\u7ed9\u51fa\u7684\u65b9\u6848\uff0c\u521b\u5efa\u8868\uff0c\u7136\u540e\u63d2\u5165\u6d4b\u8bd5\u6570\u636e\uff0c\u6570\u636e\u5e93\u4e2d\u5b58\u5728NULL\u503c\u3002<\/p>\n<pre><code class=\"sql\"> CREATE TABLE test ( c1 VARCHAR ( 32 ),\n   c2 VARCHAR ( 32 ),\n   c3 VARCHAR ( 32 ),\n   c4 VARCHAR ( 32 ) ) ENGINE = INNODB row_format = compact;<\/code><\/pre>\n<p>\u4f7f\u7528\u547d\u4ee4<code>SHOW VARIABLES LIKE 'datadir'<\/code>\u627e\u5230 ibd \u6587\u4ef6\u4f4d\u7f6e\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042440861\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u4f7f\u7528\u547d\u4ee4\u8f6c\u6362 ibd \u6587\u4ef6\u4e3a txt \u6587\u4ef6\u3002<\/p>\n<pre><code class=\"shell\">hexdump -C -v test.ibd &gt; \/Users\/irving\/test-null.txt<\/code><\/pre>\n<p>\u6253\u5f00\u6587\u4ef6\u627e\u5230 supremum \u90e8\u5206\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042440862\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u4e0d\u7528\u770b\u90a3\u4e48\u591a\uff0c\u5c31\u770b\u4e00\u90e8\u5206\uff1a<\/p>\n<blockquote>\n<p>03 02 02 01 \u662f\u4e0a\u9762\u8bf4\u7684\u53d8\u957f\u5b57\u6bb5\u957f\u5ea6\u5217\u8868\uff0c\u4ee5\u4e3a\u6211\u4eec\u67094\u4e2a\u5b57\u6bb5\uff0c\u6240\u4ee54\u4e2a\u5b57\u8282\u3002<\/p>\n<p>00 \u5c31\u662fNULL\u6807\u5fd7\u4f4d<\/p>\n<p>00 00 10 00 25 \u662f\u6570\u636e\u59345\u4e2a\u5b57\u8282<\/p>\n<\/blockquote>\n<p>\u8fd9\u4e2a\u80af\u5b9a\u6ca1\u6709\u95ee\u9898\uff0c\u7136\u540e\u518d\u6b21\u521b\u5efa\u4e00\u5f20\u8868\uff0c\u8fd9\u65f6\u5019\u5b57\u6bb5\u90fd\u662fNOT NULL\uff0c\u7136\u540e\u518d\u6b21\u6267\u884c\u547d\u4ee4\u3002<\/p>\n<pre><code class=\"sql\"> CREATE TABLE test ( c1 VARCHAR ( 32 ) NOT NULL,\n   c2 VARCHAR ( 32 ) NOT NULL,\n   c3 VARCHAR ( 32 ) NOT NULL,\n   c4 VARCHAR ( 32 ) NOT NULL ) ENGINE = INNODB row_format = compact;<\/code><\/pre>\n<p>\u62ff\u5230\u53e6\u5916\u4e00\u4e2a ibd \u6587\u4ef6\u3002<\/p>\n<p><img decoding=\"async\" referrerpolicy=\"no-referrer\" src=\"https:\/\/segmentfault.com\/img\/remote\/1460000042440863\" alt=\"\" title=\"\" loading=\"lazy\"><\/p>\n<p>\u5bf9\u6bd4\u5176\u5b9e\u5f88\u6e05\u695a\u80fd\u53d1\u73b0\u95ee\u9898\uff0c\u8fd9\u65f6\u5019\u5df2\u7ecf\u6ca1\u6709\u4e86NULL\u503c\u5217\u8868\u7684\u6807\u5fd7\u4f4d\u4e86\u3002<\/p>\n<p>SO\uff0c\u8fd9\u4e2a\u6d4b\u8bd5\u7ed3\u679c\u8bc1\u660e\uff0c\u5982\u679c\u5b58\u5728\u4efb\u610fNULL\u503c\uff0cNULL\u503c\u5217\u8868\u81f3\u5c11\u5360\u7528\u4e00\u4e2a\u5b57\u8282\u7684\u7a7a\u95f4\uff0c\u4ee5\u540e\u6bcf\u591a8\u4e2aNULL\u503c\u591a\u5360\u7528\u4e00\u4e2a\u5b57\u8282\uff0c\u5982\u679c\u90fd\u662fNOT NULL\uff0c\u5219\u4e0d\u4f1a\u5b58\u5728NULL\u503c\u5217\u8868\u6807\u8bb0\uff0c\u4e0d\u5360\u7528\u7a7a\u95f4\u3002<\/p>\n<p>\u5de8\u4eba\u7684\u80a9\u8180\uff1a<\/p>\n<blockquote>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=H5wGoS6avGj%2FtVwntnBIaA%3D%3D.pIPMevRtFd5tE59XEnyuZstDRx4FnyCkbV0BLbdcT4hjRZeDyZfE%2Fs3zKBOyXE6%2F\" rel=\"nofollow\">http:\/\/mysql.taobao.org\/month&#8230;<\/a><\/p>\n<p><a href=\"https:\/\/link.segmentfault.com\/?enc=vD1Du0NcTXOZda7vpdKCeA%3D%3D.09VBu8uRIf2hGM9AwYlG%2FwwIJ%2BBKtkJ877lEjEvmDzSw41a%2BIjVxeGJaqycY1vKNEnPift8bNJ5Og4obrvfidsIqDhxYLlffUsQ4Q9tr4PY%3D\" rel=\"nofollow\">https:\/\/www.cnblogs.com\/zhouj&#8230;<\/a><\/p>\n<\/blockquote>\n<p><a href=\"https:\/\/segmentfault.com\/a\/1190000042440855\">https:\/\/segmentfault.com\/a\/1190000042440855<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5728\u4e4b\u524d\u7684\u6587\u7ae0\u63d0\u5230\u8fc7\u4e00\u4e2a\u95ee\u9898\uff0c\u800c\u4e14\u7f51\u4e0a\u5f88\u591a\u6587\u7ae0\u4e5f\u662f\u8fd9\u4e48\u8bf4\u7684\uff0c\u524d\u51e0\u5929\u6709\u4eba\u5bf9\u8fd9\u4e2a\u95ee\u9898\u63d0\u51fa\u4e86\u4e00\u70b9\u4e0d\u540c\u7684\u610f\u89c1\uff0c\u62b1\u7740\u8c28\u614e\u7684 [&hellip;]<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[],"tags":[],"class_list":["post-10006421","post","type-post","status-publish","format-standard","hentry"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10006421","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10006421"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10006421\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10006421"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10006421"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10006421"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}