{"id":50458,"date":"2023-11-04T05:52:33","date_gmt":"2022-11-03T14:46:18","guid":{"rendered":"https:\/\/www.silicloud.com\/zh\/blog\/leveldb%e7%9a%84%e8%ae%be%e8%ae%a1%e6%96%87%e6%a1%a3%e7%bf%bb%e8%af%91\/"},"modified":"2024-05-04T07:25:51","modified_gmt":"2024-05-03T23:25:51","slug":"leveldb%e7%9a%84%e8%ae%be%e8%ae%a1%e6%96%87%e6%a1%a3%e7%bf%bb%e8%af%91","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/zh\/blog\/leveldb%e7%9a%84%e8%ae%be%e8%ae%a1%e6%96%87%e6%a1%a3%e7%bf%bb%e8%af%91\/","title":{"rendered":"LevelDB\u7684\u8bbe\u8ba1\u6587\u6863\u7ffb\u8bd1"},"content":{"rendered":"<p>Cassandra\u7684\u5b58\u50a8\u4e2d\u5b58\u5728\u4e24\u79cd\u538b\u7f29\u7b56\u7565\uff0c\u5373SizedTierCompaction\u548c\u57fa\u4e8eGoogle 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\/>\n\u65b0\u3057\u304f\u4f5c\u3063\u305fsstable\u3092\u82e5\u3044(level-0)\u30ec\u30d9\u30eb\u306b\u8ffd\u52a0\u3059\u308b<\/p>\n<h2>\u538b\u7f29<\/h2>\n<p>\u5f53\u7ea7\u522bL\u7684\u5927\u5c0f\u8fbe\u5230\u4e0a\u9650\u65f6\uff0c\u4f1a\u5728\u540e\u53f0\u7ebf\u7a0b\u4e2d\u8fdb\u884c\u538b\u7f29\u3002\u538b\u7f29\u4f1a\u9009\u62e9\u6765\u81ea\u7ea7\u522bL\u7684\u4e00\u4e2a\u6587\u4ef6\u4ee5\u53ca\u4e0b\u4e00\u4e2a\u7ea7\u522bL+1\u4e2d\u6240\u6709\u4e0e\u4e4b\u91cd\u53e0\u7684\u6587\u4ef6\u3002\u8bf7\u6ce8\u610f\uff0c\u5373\u4f7f\u7ea7\u522bL\u6587\u4ef6\u53ea\u4e0e\u7ea7\u522b(L+1)\u6587\u4ef6\u7684\u4e00\u90e8\u5206\u91cd\u53e0\uff0c\u6574\u4e2a\u7ea7\u522b(L+1)\u6587\u4ef6\u4e5f\u4f1a\u88ab\u7528\u4f5c\u538b\u7f29\u7684\u8f93\u5165\uff0c\u5e76\u5728\u538b\u7f29\u540e\u88ab\u4e22\u5f03\u3002\u987a\u4fbf\u8bf4\u4e00\u53e5\uff1a\u7ea7\u522b0\u662f\u7279\u6b8a\u7684\uff08\u5176\u4e2d\u7684\u6587\u4ef6\u53ef\u80fd\u76f8\u4e92\u91cd\u53e0\uff09\uff0c\u6240\u4ee5\u7ea7\u522b0\u5230\u7ea7\u522b1\u7684\u538b\u7f29\u4f1a\u7279\u522b\u5904\u7406\uff1a\u7ea7\u522b0\u7684\u538b\u7f29\u53ef\u4ee5\u9009\u62e9\u8fd9\u4e9b\u6587\u4ef6\u76f8\u4e92\u91cd\u53e0\u65f6\u7684\u4e00\u4e2a\u6216\u591a\u4e2a\u7ea7\u522b0\u6587\u4ef6\u3002<\/p>\n<p>\u538b\u7f29\u4f1a\u5408\u5e76\u6240\u9009\u6587\u4ef6\u5e76\u751f\u6210\u4e00\u7cfb\u5217\u7684\u7ea7\u522b(L+1)\u6587\u4ef6\u3002\u5f53\u5f53\u524d\u7684\u8f93\u51fa\u6587\u4ef6\u8fbe\u5230\u76ee\u6807\u6587\u4ef6\u5927\u5c0f(2MB)\u65f6\uff0c\u5c06\u5207\u6362\u5230\u751f\u6210\u65b0\u7684\u7ea7\u522b(L+1)\u6587\u4ef6\u3002\u53e6\u5916\uff0c\u5982\u679c\u5f53\u524d\u7684\u8f93\u51fa\u6587\u4ef6\u4e0e10\u4e2a\u4ee5\u4e0a\u7684\u7ea7\u522b(L+2)\u6587\u4ef6\u91cd\u53e0\u5e76\u4e14\u663e\u8457\u589e\u957f\uff0c\u4e5f\u4f1a\u5207\u6362\u5230\u751f\u6210\u65b0\u6587\u4ef6\u3002\u8fd9\u4e2a\u6700\u540e\u7684\u89c4\u5219\u662f\u4e3a\u4e86\u786e\u4fdd\u540e\u7eed\u7ea7\u522b(L+1)\u6587\u4ef6\u4e0d\u4f1a\u9009\u62e9\u592a\u591a\u7ea7\u522b(L+2)\u6587\u4ef6\u8fdb\u884c\u538b\u7f29\u3002<\/p>\n<p>\u65e7\u6587\u4ef6\u4f1a\u88ab\u4e22\u5f03\uff0c\u65b0\u6587\u4ef6\u4f1a\u88ab\u6dfb\u52a0\u5230\u7b49\u5f85\u72b6\u6001\u3002<\/p>\n<p>\u7279\u5b9a\u7ea7\u522b\u7684\u538b\u7f29\u901a\u8fc7\u952e\u7a7a\u95f4\u5faa\u73af\u3002\u66f4\u8be6\u7ec6\u5730\u8bf4\uff0c\u6bcf\u4e2a\u7ea7\u522bL\u90fd\u4f1a\u8bb0\u4f4f\u8be5\u7ea7\u522bL\u538b\u7f29\u7684\u6700\u540e\u4e00\u4e2a\u952e\u3002\u5728\u4e0b\u4e00\u4e2a\u7ea7\u522bL\u7684\u538b\u7f29\u4e2d\uff0c\u5c06\u9009\u62e9\u4ece\u8be5\u952e\u4e4b\u540e\u5f00\u59cb\u7684\u7b2c\u4e00\u4e2a\u6587\u4ef6\u3002\uff08\u5982\u679c\u6ca1\u6709\u8fd9\u6837\u7684\u6587\u4ef6\uff0c\u5219\u8fd4\u56de\u952e\u7a7a\u95f4\u7684\u5f00\u5934\uff09<\/p>\n<p>\u5982\u679cCompaction\u5e9f\u5f03\u4e86\u88ab\u8986\u76d6\u7684\u503c\uff0c\u90a3\u4e48\u5982\u679c\u5728\u8f83\u9ad8\u7ea7\u522b\u4e0a\u4e0d\u5b58\u5728\u5177\u6709\u4e0e\u5f53\u524d\u952e\u91cd\u53e0\u7684\u8303\u56f4\u7684\u6587\u4ef6\uff0c\u8fd8\u4f1a\u4e22\u5f03\u5220\u9664\u6807\u8bb0\u3002<\/p>\n<h2>\u65f6\u95f4<\/h2>\n<p>Level-0\u538b\u7f29\u4eceLevel-0\u8bfb\u53d6\u6700\u591a\u56db\u4e2a1MB\u6587\u4ef6\uff0c\u5e76\u8bfb\u53d6\u6240\u6709Level-1\u6587\u4ef6\u7684\u6700\u5dee\u60c5\u51b5\uff08\u603b\u517110MB\uff09\u3002\u4e5f\u5c31\u662f\u8bf4\uff0c\u8bfb\u53d614MB\u5e76\u5199\u516514MB\u3002<\/p>\n<p>\u8bf7\u4eceL\u7ea7\u522b\u4e2d\u9009\u62e9\u4e00\u4e2a2MB\u6587\u4ef6\uff0c\u4f46\u9664\u4e86\u7279\u6b8a\u7684\u7ea7\u522b0\u538b\u7f29\u5916\u3002\u5e76\u4e14\u4eceL+1\u7ea7\u522b\u4e2d\u9009\u62e912\u4e2a\u6587\u4ef6\uff08L+1\u7ea7\u522b\u662fL\u7ea7\u522b\u5927\u5c0f\u768410\u500d\uff0c\u6240\u4ee5\u670910\u4e2a\u6587\u4ef6\uff0c\u53e6\u5916\u76842\u4e2a\u6587\u4ef6\u662f\u56e0\u4e3aL\u7ea7\u522b\u7684\u6587\u4ef6\u8303\u56f4\u901a\u5e38\u4e0eL+1\u7ea7\u522b\u7684\u6587\u4ef6\u8303\u56f4\u4e0d\u5bf9\u9f50\u800c\u4ea7\u751f\u7684\u8fb9\u754c\uff09\u3002\u8003\u8651\u523026MB\u7684\u8bfb\u5199\u4ee5\u53ca100MB\/s\u7684\u78c1\u76d8IO\u901f\u7387\uff08\u73b0\u4ee3\u9a71\u52a8\u5668\u7684\u7c97\u7565\u8303\u56f4\uff09\uff0c\u538b\u7f29\u7684\u6210\u672c\u6700\u574f\u60c5\u51b5\u4e0b\u5927\u7ea6\u4e3a0.5\u79d2\u3002<\/p>\n<p>\u5982\u679c\u5bf9\u540e\u53f0\u5199\u5165\u8fdb\u884c\u4e86\u67d0\u79cd\u5c0f\u7684\u9650\u5236\uff0c\u4f8b\u5982\u5c06\u5176\u9650\u5236\u5728100MB\/s\u768410%\uff08\u537310MB\/s\uff09\uff0c\u90a3\u4e48\u538b\u7f29\u53ef\u80fd\u6700\u591a\u9700\u89815\u79d2\u949f\u3002\u5982\u679c\u7528\u6237\u4ee510MB\/s\u7684\u901f\u5ea6\u8fdb\u884c\u5199\u5165\uff0c\u90a3\u4e48\u6211\u4eec\u53ef\u80fd\u4f1a\u79ef\u7d2f\u5f88\u591a\u7ea7\u522b0\u6587\u4ef6\uff08\u7ea650\u4e2a\uff0c\u5bf9\u5e945*10MB\uff09\u3002\u7531\u4e8e\u6bcf\u6b21\u8bfb\u53d6\u90fd\u9700\u8981\u5408\u5e76\u5927\u91cf\u6587\u4ef6\uff0c\u8fd9\u53ef\u80fd\u4f1a\u6781\u5927\u5730\u589e\u52a0\u8bfb\u53d6\u7684\u6210\u672c\u3002<\/p>\n<p>\u89e3\u51b3\u65b9\u68481\uff1a\u4e3a\u4e86\u7f13\u89e3\u8fd9\u4e2a\u95ee\u9898\uff0c\u5728Level 0\u6587\u4ef6\u6570\u91cf\u8f83\u591a\u65f6\uff0c\u6211\u8ba4\u4e3a\u9700\u8981\u63d0\u9ad8\u65e5\u5fd7\u5f00\u5173\u7684\u9608\u503c\u3002\u7136\u800c\uff0c\u503c\u5f97\u6ce8\u610f\u7684\u662f\uff0c\u8bbe\u7f6e\u8f83\u5927\u7684\u9608\u503c\u4e5f\u53ef\u80fd\u5e26\u6765\u66f4\u591a\u7684\u5185\u5b58\u6d88\u8017\uff0c\u4ee5\u7ef4\u62a4\u76f8\u5e94\u7684\u5185\u5b58\u8868\u3002<\/p>\n<p>\u89e3\u51b3\u65b9\u68482\uff1a\u5f53\u7ea7\u522b0\u6587\u4ef6\u6570\u91cf\u589e\u52a0\u65f6\uff0c\u6211\u8ba4\u4e3a\u9700\u8981\u4eba\u5de5\u964d\u4f4e\u5199\u5165\u901f\u7387\u3002<\/p>\n<p>\u89e3\u51b3\u65b9\u68483\uff1a\u6211\u4eec\u6b63\u5728\u52aa\u529b\u964d\u4f4e\u5e7f\u6cdb\u5408\u5e76\u7684\u6210\u672c\u3002\u53ef\u80fd\u5927\u591a\u65700\u7ea7\u6587\u4ef6\u90fd\u5b58\u50a8\u5728\u7f13\u5b58\u4e2d\u800c\u672a\u7ecf\u8fc7\u538b\u7f29\uff0c\u56e0\u6b64\u53ea\u9700\u8981\u62c5\u5fc3\u5408\u5e76\u8fed\u4ee3\u5668\u7684O(N)\u590d\u6742\u5ea6\u3002<\/p>\n<h2>\u6587\u4ef6\u6570\u91cf<\/h2>\n<p>\u53ef\u4ee5\u4f7f\u7528\u66f4\u5927\u7684\u6587\u4ef6\u6765\u4ee3\u66ff\u59cb\u7ec8\u521b\u5efa2MB\u6587\u4ef6\uff0c\u4ee5\u4fbf\u63d0\u9ad8\u603b\u6587\u4ef6\u6570\uff0c\u5c3d\u7ba1\u8fd9\u5c06\u9700\u8981\u66f4\u731b\u70c8\u7684\u538b\u7f29\u3002 \u53e6\u5916\uff0c\u60a8\u8fd8\u53ef\u4ee5\u5c06\u6587\u4ef6\u96c6\u5206\u7247\u5230\u591a\u4e2a\u76ee\u5f55\u4e2d\u3002<\/p>\n<p>\u6839\u636e\u57282011\u5e742\u67084\u65e5\u8fdb\u884c\u7684\u5728ext3\u6587\u4ef6\u7cfb\u7edf\u4e0a\u7684\u5b9e\u9a8c\uff0c\u5f53\u76ee\u5f55\u4e2d\u5b58\u5728\u4e0d\u540c\u6570\u91cf\u7684\u6587\u4ef6\u65f6\uff0c\u8981\u6253\u5f00100K\u4e2a\u6587\u4ef6\u9700\u8981\u4ee5\u4e0b\u65f6\u95f4\u3002<\/p>\n<div>\n<div class=\"post-table\">Files in directoryMicroseconds to open a file10009100001010000016<\/div>\n<\/div>\n<p>\u4e5f\u8bb8\u5728\u73b0\u4ee3\u5316\u7684\u6587\u4ef6\u7cfb\u7edf\u4e2d\uff0c\u5e76\u4e0d\u9700\u8981\u5206\u7247\uff0c\u662f\u5427\uff1f<\/p>\n<h2>\u6062\u590d<\/h2>\n<ul class=\"post-ul\">\n<li style=\"list-style-type: none;\">\n<ul class=\"post-ul\">CURRENT\u3092\u30ea\u30fc\u30c9\u3057\u3066\u6700\u65b0\u306e\u30b3\u30df\u30c3\u30c8\u3055\u308c\u305fMANIFEST\u3092\u898b\u3064\u3051\u308b<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<ul 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