{"id":1229,"date":"2015-05-26T22:24:00","date_gmt":"2015-05-26T14:24:00","guid":{"rendered":"http:\/\/coderbee.net\/?p=1229"},"modified":"2015-06-02T23:35:33","modified_gmt":"2015-06-02T15:35:33","slug":"%e3%80%8a%e5%9f%ba%e4%ba%8e-oracle-%e7%9a%84-sql-%e4%bc%98%e5%8c%96%e3%80%8b%e7%ac%94%e8%ae%b0-%e7%ac%ac%e4%b8%80%e7%ab%a0-oracle-%e9%87%8c%e7%9a%84%e4%bc%98%e5%8c%96%e5%99%a8","status":"publish","type":"post","link":"https:\/\/coderbee.net\/index.php\/db\/20150526\/1229","title":{"rendered":"\u300a\u57fa\u4e8e Oracle \u7684 SQL \u4f18\u5316\u300b\u7b14\u8bb0 \u7b2c\u4e00\u7ae0 Oracle \u91cc\u7684\u4f18\u5316\u5668"},"content":{"rendered":"<h3>CBO \u76f8\u5173\u57fa\u7840<\/h3>\n<p>cardinality \uff1a\u6307\u5b9a\u7ed3\u679c\u96c6\u7684\u884c\u6570\uff0c\u5b9e\u9645\u4e0a\u8868\u793a\u5bf9\u76ee\u6807 SQL \u7684\u67d0\u4e2a\u5177\u4f53\u6b65\u9aa4\u7684\u6267\u884c\u7ed3\u679c\u6240\u5305\u542b\u8bb0\u5f55\u6570\u7684\u4f30\u7b97\u3002\u5982\u679c\u662f\u9488\u5bf9\u6574\u4e2a\u76ee\u6807 SQL\uff0c\u90a3\u4e48\u6b64\u65f6\u7684 cardinality \u5c31\u8868\u793a\u5bf9\u8be5 SQL \u6700\u7ec8\u6267\u884c\u7ed3\u679c\u6240\u5305\u542b\u8bb0\u5f55\u6570\u7684\u4f30\u7b97\u3002cardinality \u503c\u8d8a\u5927\uff0c\u5bf9\u5e94\u7684\u6210\u672c\u5c31\u8d8a\u9ad8\u3002<\/p>\n<p>selectivity \u9009\u62e9\u5ea6\uff1a\u662f\u6307\u65bd\u52a0\u6307\u5b9a\u8c13\u8bcd\u6761\u4ef6\u540e\u8fd4\u56de\u7ed3\u679c\u96c6\u7684\u8bb0\u5f55\u6570\u5360\u672a\u65bd\u52a0\u4efb\u4f55\u8c13\u8bcd\u6761\u4ef6\u7684\u539f\u59cb\u7ed3\u679c\u96c6\u7684\u8bb0\u5f55\u6570\u7684\u6bd4\u7387\u3002\u8ba1\u7b97\u516c\u5f0f\u4e3a <code>selectivity = \u6307\u5b9a\u8c13\u8bcd\u6761\u4ef6\u540e\u8fd4\u56de\u7ed3\u679c\u96c6\u7684\u8bb0\u5f55\u6570 \/ \u672a\u65bd\u52a0\u4efb\u4f55\u8c13\u8bcd\u6761\u4ef6\u7684\u539f\u59cb\u7ed3\u679c\u96c6\u7684\u8bb0\u5f55\u6570<\/code>\u3002\u8fd9\u4e2a\u53d6\u503c\u5904\u4e8e <code>0 - 1<\/code> \u4e4b\u95f4\uff0c\u503c\u8d8a\u5c0f\u8d8a\u597d\uff0c\u8bf4\u660e\u9009\u62e9\u6027\u9ad8\uff08\u80fd\u8fc7\u6ee4\u66f4\u591a\u4e0d\u7b26\u5408\u6761\u4ef6\u7684\u6570\u636e\uff09\u3002<\/p>\n<p>\u5bf9\u4e8e\u6bcf\u4e00\u79cd\u5177\u4f53\u60c5\u51b5\uff0cselectivity \u4f1a\u6709\u4e0d\u540c\u7684\u8ba1\u7b97\u516c\u5f0f\u3002<\/p>\n<p>\u6700\u7b80\u5355\u7684\u60c5\u51b5\u662f\u5bf9\u76ee\u6807\u5217\u505a\u7b49\u503c\u67e5\u8be2\u65f6 selectivity \u7684\u8ba1\u7b97\u516c\u5f0f\uff0c\u5728\u76ee\u6807\u5217\u4e0a\u6ca1\u6709\u76f4\u65b9\u56fe\u4e14\u6ca1\u6709 NULL \u503c\u7684\u60c5\u51b5\u4e0b\uff0c\u7528\u76ee\u6807\u5217\u505a\u7b49\u503c\u67e5\u8be2\u65f6\u7684 selectivity \u7684\u8ba1\u7b97\u516c\u5f0f\u4e3a <code>selectivity = 1 \/ NUM_DISTINCT<\/code>\uff0cNUM_DISTINCT \u8868\u793a\u76ee\u6807\u5217\u7684 distinct \u503c\u7684\u6570\u91cf\u3002<\/p>\n<p>transitivity \u53ef\u4f20\u9012\u6027\uff1a\u662f CBO \u5728\u67e5\u8be2\u8f6c\u6362\u4e2d\u6240\u505a\u7684\u7b2c\u4e00\u4ef6\u4e8b\uff0c\u662f\u6307 CBO \u53ef\u80fd\u4f1a\u5bf9\u539f\u76ee\u6807 SQL \u505a\u7b80\u5355\u7684\u7b49\u4ef7\u6539\u5199\uff0c\u5373\u5728\u539f\u76ee\u6807 SQL \u4e2d\u52a0\u4e0a\u6839\u636e\u8be5 SQL \u73b0\u6709\u7684\u8c13\u8bcd\u6761\u4ef6\u63a8\u7b97\u51fa\u6765\u7684\u65b0\u7684\u8c13\u8bcd\u6761\u4ef6\uff0c\u8fd9\u4e48\u505a\u7684\u76ee\u7684\u662f\u63d0\u4f9b\u66f4\u591a\u7684\u6267\u884c\u8def\u5f84\u7ed9 CBO \u505a\u9009\u62e9\uff0c\u8fdb\u800c\u5f97\u5230\u66f4\u9ad8\u6548\u6267\u884c\u8ba1\u5212\u7684\u53ef\u80fd\u6027\u3002<\/p>\n<p>Oracle \u4e2d\u53ef\u4f20\u9012\u6027\u5206\u4e0b\u5217\u4e09\u79cd\u60c5\u5f62\uff1a<\/p>\n<ul>\n<li>\u7b80\u5355\u7684\u8c13\u8bcd\u4f20\u9012\uff1a\u6bd4\u5982 <code>t1.c1 = t2.c1 and t1.c1 = 10<\/code> \uff0c\u989d\u5916\u6dfb\u52a0 <code>t2.c1 = 10<\/code>\u3002<\/li>\n<li>\u8fde\u63a5\u8c13\u8bcd\u4f20\u9012\uff1a\u6bd4\u5982 <code>t1.c1 = t2.c1 and t2.c1 = t3.c1<\/code>\uff0c\u989d\u5916\u6dfb\u52a0 <code>t1.c1 = t3.c1<\/code>\u3002<\/li>\n<li>\u5916\u8fde\u63a5\u8c13\u8bcd\u4f20\u9012\uff1a\u6bd4\u5982 <code>t1.c1 = t2.c1(+) and t1.c1 = 10<\/code>\uff0c\u989d\u5916\u6dfb\u52a0 <code>t2.c1 (+)= 10<\/code>\u3002<\/li>\n<\/ul>\n<p><!--more--><\/p>\n<p>CBO\u7684\u7f3a\u9677\uff1a<\/p>\n<ol>\n<li>CBO \u4f1a\u9ed8\u8ba4\u76ee\u6807 SQL \u8bed\u53e5 where \u6761\u4ef6\u4e2d\u51fa\u73b0\u7684\u5404\u4e2a\u5217\u4e4b\u95f4\u662f\u72ec\u7acb\u7684\uff0c\u6ca1\u6709\u5173\u8054\u5173\u7cfb\u3002<\/li>\n<li>CBO \u4f1a\u5047\u8bbe\u6240\u6709\u7684\u76ee\u6807 SQL \u90fd\u662f\u5355\u72ec\u6267\u884c\u7684\uff0c\u5e76\u4e14\u4e92\u4e0d\u5e72\u6270\u3002\u6bd4\u5982\u6ca1\u6709\u8003\u8651\u5230\u7f13\u5b58\uff0c\u5c31\u4f1a\u9ad8\u4f30\u6210\u672c\u3002<\/li>\n<li>CBO \u5bf9\u76f4\u65b9\u56fe\u7edf\u8ba1\u4fe1\u606f\u6709\u8bf8\u591a\u9650\u5236\u3002<\/li>\n<li>CBO \u5728\u89e3\u6790\u591a\u8868\u5173\u8054\u7684\u76ee\u6807 SQL \u65f6\uff0c\u53ef\u80fd\u4f1a\u6f0f\u9009\u6b63\u786e\u7684\u6267\u884c\u8ba1\u5212\u3002\u968f\u7740\u591a\u8868\u5173\u8054\u7684\u76ee\u6807 SQL \u6240\u5305\u542b\u7684\u6570\u91cf\u7684\u9012\u589e\uff0c\u5404\u8868\u4e4b\u95f4\u7684\u8fde\u63a5\u987a\u5e8f\u4f1a\u5448\u51e0\u4f55\u7ea7\u6570\u589e\u957f\uff0c\u5373\u8be5 SQL \u5404\u79cd\u53ef\u80fd\u7684\u6267\u884c\u8def\u5f84\u7684\u603b\u6570\u4e5f\u4f1a\u5448\u51e0\u4f55\u7ea7\u6570\u589e\u957f\u3002Oracle \u4e0d\u53ef\u80fd\u68c0\u67e5\u6240\u6709\u7684\u6267\u884c\u8ba1\u5212\uff0c\u56e0\u6b64\u53ef\u80fd\u4f1a\u6f0f\u9009\u3002<\/li>\n<\/ol>\n<h2>\u4f18\u5316\u5668\u57fa\u7840\u77e5\u8bc6<\/h2>\n<h3>\u4f18\u5316\u5668\u6a21\u5f0f<\/h3>\n<p>\u4f18\u5316\u5668\u7684\u6a21\u5f0f\u7528\u4e8e\u51b3\u5b9a\u5728 Oracle \u89e3\u6790\u76ee\u6807 SQL \u65f6\u6240\u7528\u4f18\u5316\u5668\u7684\u7c7b\u578b\uff0c\u4ee5\u53ca\u51b3\u5b9a\u5f53\u4f7f\u7528 CBO \u65f6\u8ba1\u7b97\u6210\u672c\u503c\u7684\u4fa7\u91cd\u70b9\u3002<\/p>\n<p>\u4f18\u5316\u5668\u7684\u6a21\u5f0f\u7531\u53c2\u6570 <code>OPTIMIZER_MODE<\/code> \u7684\u503c\u6765\u51b3\u5b9a\uff0c\u53ef\u9009\u7684\u53d6\u503c\u6709\uff1a<code>RULE, CHOOSE,  FIRST_ROWS_n(n=1, 10, 100, 1000),  FIRST_ROWS,  ALL_ROWS<\/code>\u3002<\/p>\n<p>\u53ef\u7528\u8fd9\u6837\u7684\u8bed\u53e5\u66f4\u6539\u6a21\u5f0f\uff1a <code>alter  session  set  optimizer_mode = rule;<\/code><\/p>\n<p>\u5404\u4e2a\u503c\u7684\u542b\u4e49\u5982\u4e0b\uff1a<\/p>\n<ul>\n<li>RULE\uff1a\u8868\u793a Oracle \u5c06\u4f7f\u7528 RBO \u6765\u89e3\u6790\u76ee\u6807 SQL\uff0c\u6b64\u65f6\u76ee\u6807 SQL \u6240\u6d89\u53ca\u7684\u5404\u4e2a\u5bf9\u8c61\u7684\u7edf\u8ba1\u4fe1\u606f\u5bf9\u4e8e RBO \u6765\u8bf4\u6ca1\u6709\u4efb\u4f55\u4f5c\u7528\u3002<\/li>\n<li>CHOOSE\uff1aoracle 9i \u4e2d\u7684\u9ed8\u8ba4\u503c\u3002\u8868\u793a\u53ea\u8981\u76ee\u6807 SQL \u4e2d\u6240\u6d89\u53ca\u7684\u8868\u5bf9\u8c61\u4e2d\u6709\u4e00\u4e2a\u6709\u7edf\u8ba1\u4fe1\u606f\uff0c\u90a3\u4e48 Oracle \u5728\u89e3\u6790\u8be5 SQL \u65f6\u5c31\u4f1a\u4f7f\u7528 CBO\uff1b\u5982\u679c\u8be5 SQL \u6d89\u53ca\u7684\u6240\u6709\u8868\u5bf9\u8c61\u90fd\u6ca1\u6709\u7edf\u8ba1\u4fe1\u606f\uff0c\u5c31\u4f7f\u7528 RBO\u3002<\/li>\n<li>FIRST_ROWS_n(n=1, 10, 100, 1000)\uff1aCBO \u5728\u9009\u62e9\u6267\u884c\u8ba1\u5212\u65f6\u6240\u91c7\u7528\u7684\u539f\u5219\u4e0d\u518d\u662f\u9009\u62e9\u6210\u672c\u6700\u5c0f\u7684\u6267\u884c\u8def\u5f84\uff0c\u800c\u662f\u80fd\u591f\u4ee5\u6700\u5feb\u901f\u5ea6\u8fd4\u56de\u5934 <code>n(n=1, 10, 100, 1000)<\/code>  \u6761\u8bb0\u5f55\u6240\u5bf9\u5e94\u7684\u6267\u884c\u8def\u5f84\u3002<\/li>\n<li>FIRST_ROWS\uff1a\u5728 oracle 9i \u4e2d\u5df2\u8fc7\u65f6\u7684\u53c2\u6570\u3002<\/li>\n<li>ALL_ROWS\uff1aoracle 10g \u53ca\u540e\u7eed\u7248\u672c\u7684\u9ed8\u8ba4\u503c\u3002CBO \u5728\u8ba1\u7b97\u8be5 SQL \u7684\u5404\u6761\u6267\u884c\u8def\u5f84\u7684\u6210\u672c\u503c\u65f6\u4fa7\u91cd\u70b9\u5728\u4e8e\u6700\u4f73\u7684\u541e\u5410\u91cf\u3002<\/li>\n<\/ul>\n<h3>\u7ed3\u679c\u96c6\uff08row source\uff09<\/h3>\n<p>\u7ed3\u679c\u96c6\u662f\u6307\u5305\u542b\u6307\u5b9a\u6267\u884c\u7ed3\u679c\u7684\u96c6\u5408\u3002\u5bf9\u4e8e CBO\uff0c\u5bf9\u5e94\u6267\u884c\u8ba1\u5212\u4e2d\u7684\u5217\uff08rows\uff09\u53cd\u5e94\u7684\u5c31\u662f CBO \u5bf9\u4e8e\u76f8\u5173\u6267\u884c\u6b65\u9aa4\u6240\u5bf9\u5e94\u8f93\u51fa\u7ed3\u679c\u7684\u8bb0\u5f55\u6570\uff08\u5373 Cardianlity\uff09\u7684\u4f30\u7b97\u503c\u3002<\/p>\n<h3>\u8bbf\u95ee\u6570\u636e\u7684\u65b9\u6cd5<\/h3>\n<p>\u8bbf\u95ee\u8868\u4e2d\u6570\u636e\u7684\u65b9\u6cd5\u6709\u4e24\u79cd\uff0c\u4e00\u79cd\u662f\u76f4\u63a5\u8bbf\u95ee\u8868\uff1b\u53e6\u4e00\u79cd\u662f\u5148\u8bbf\u95ee\u7d22\u5f15\uff0c\u518d\u56de\u8868\uff08\u5982\u679c\u901a\u8fc7\u7d22\u5f15\u5c31\u80fd\u5f97\u5230\u6240\u9700\u6570\u636e\uff0c\u5219\u4e0d\u9700\u8981\u56de\u8868\uff09\u3002<\/p>\n<p>\u8bbf\u95ee\u8868\u4e2d\u6570\u636e\u7684\u65b9\u6cd5\u6709\u4e24\u79cd\uff1a\u5168\u8868\u626b\u63cf\u548c rowid \u626b\u63cf\u3002<\/p>\n<ul>\n<li>\n<p>\u5168\u8868\u626b\u63cf\uff1aOracle \u5728\u8bbf\u95ee\u76ee\u6807\u8868\u91cc\u7684\u6570\u636e\u65f6\uff0c\u4f1a\u4ece\u8be5\u8868\u6240\u5360\u7528\u7684\u7b2c\u4e00\u4e2a\u533a\uff08EXTENT\uff09\u7684\u7b2c\u4e00\u4e2a\u5757\u5f00\u59cb\u626b\u63cf\uff0c\u4e00\u76f4\u626b\u63cf\u5230\u8be5\u8868\u7684\u9ad8\u6c34\u4f4d\u7ebf\uff08High Water Mark\uff0cHWM\uff09\uff0c\u8fd9\u6bb5\u8303\u56f4\u5185\u7684\u6240\u6709\u6570\u636e\u5757 Oracle \u90fd\u5fc5\u987b\u8bfb\u5230\u3002<br \/>\n\u671f\u95f4 Oracle \u4f1a\u5bf9\u8bfb\u5230\u7684\u6240\u6709\u6570\u636e\u65bd\u52a0\u76ee\u6807 SQL \u91cc where \u6761\u4ef6\u4e2d\u7684\u8fc7\u6ee4\u6761\u4ef6\uff0c\u8fd4\u56de\u7b26\u5408\u6761\u4ef6\u7684\u6570\u636e\u3002Oracle \u5728\u505a\u5168\u8868\u626b\u63cf\u64cd\u4f5c\u65f6\u4f1a\u4f7f\u7528\u591a\u5757\u8bfb\uff0c\u8fd9\u5728\u76ee\u6807\u8868\u7684\u6570\u636e\u91cf\u4e0d\u5927\u65f6\u6267\u884c\u6548\u7387\u662f\u5f88\u9ad8\u7684\u3002\u5168\u8868\u626b\u63cf\u7684\u6700\u5927\u95ee\u9898\u5728\u4e8e\u8d70\u5168\u8868\u626b\u63cf\u7684\u76ee\u6807 SQL \u7684\u6267\u884c\u65f6\u95f4\u4f1a\u4e0d\u7a33\u5b9a\u3001\u4e0d\u53ef\u63a7\uff0c\u4f1a\u968f\u7740\u76ee\u6807\u6570\u636e\u91cf\u7684\u589e\u52a0\u800c\u9012\u589e\u3002<\/p>\n<\/li>\n<li>\n<p>rowid \u626b\u63cf\uff1arowid \u8868\u793a Oracle \u4e2d\u6570\u636e\u884c\u8bb0\u5f55\u6240\u5728\u7684\u7269\u7406\u5b58\u50a8\u5730\u5740\u3002rowid \u626b\u63cf\u6709\u4e24\u79cd\u65b9\u5f0f\uff0c\u4e00\u79cd\u662f\u6839\u636e\u7528\u6237\u8f93\u5165\u7684 rowid \u7684\u503c\u76f4\u63a5\u53bb\u8bbf\u95ee\u5bf9\u5e94\u7684\u6570\u636e\u884c\u8bb0\u5f55\uff0c\u53e6\u4e00\u79cd\u662f\u5148\u8bbf\u95ee\u76f8\u5173\u7d22\u5f15\uff0c\u5f97\u5230 rowid \u540e\u518d\u56de\u8868\u8bbf\u95ee\u5bf9\u5e94\u6570\u636e\u884c\u8bb0\u5f55\u3002<\/p>\n<\/li>\n<\/ul>\n<blockquote>\n<p><em>\u9ad8\u6c34\u4f4d\u7ebf\uff08high water mark\uff0cHWM\uff09<\/em>\uff1a\u6c34\u5e93\u6da8\u6c34\u65f6\uff0c\u6c34\u4f4d\u4f1a\u4e0a\u79fb\uff0c\u6c34\u5e93\u653e\u6c34\u540e\uff0c\u66fe\u7ecf\u7684\u6700\u9ad8\u6c34\u4f4d\u7684\u75d5\u8ff9\u8fd8\u53ef\u4ee5\u770b\u89c1\u3002\u5728 Oracle \u4e2d\uff0c\u5982\u679c\u5bf9\u76ee\u6807\u8868\u4e0d\u505c\u5730\u63d2\u5165\u6570\u636e\uff0c\u5f53\u5206\u914d\u7ed9\u8be5\u8868\u7684\u73b0\u6709\u7a7a\u95f4\u4e0d\u8db3\u65f6\uff0c\u9ad8\u6c34\u4f4d\u7ebf\u5c31\u4f1a\u5411\u4e0a\u79fb\u3002<code>delete<\/code> \u65e0\u6cd5\u964d\u4f4e\u9ad8\u6c34\u4f4d\u7ebf\uff0c<code>truncate<\/code> \u53ef\u4ee5\u3002\u9ad8\u6c34\u4f4d\u7ebf\u7684\u8fd9\u79cd\u7279\u6027\u5e26\u6765\u7684\u526f\u4f5c\u7528\u662f\uff0c\u5373\u4f7f\u7528 <code>delete<\/code> \u628a\u76ee\u6807\u8868\u4e2d\u7684\u6240\u6709\u6570\u636e\u90fd\u5220\u4e86\uff0c\u9ad8\u6c34\u4f4d\u7ebf\u8fd8\u4f1a\u5728\u539f\u6765\u7684\u4f4d\u7f6e\uff0c\u6b64\u65f6\u5bf9\u8be5\u8868\u7684\u5168\u8868\u626b\u63cf\u64cd\u4f5c\u6240\u8017\u8d39\u7684\u65f6\u95f4\u4e0e\u4e4b\u524d\u76f8\u6bd4\u4e0d\u4f1a\u6709\u660e\u663e\u7684\u6539\u89c2\u3002<br \/>\n  <br \/>\n     \u6700\u8fd1\u751f\u4ea7\u73af\u5883\u5c31\u51fa\u4e86\u8fd9\u79cd\u95ee\u9898\uff1a\u7528\u6237\u767b\u5f55\u540e\u7684\u51ed\u8bc1\u4f1a\u4fdd\u5b58\u5728\u6570\u636e\u5e93\u91cc\uff0c\u6709job\u5b9a\u65f6\u628a\u8fc7\u671f\u7684\u51ed\u8bc1\u5220\u9664\uff0c\u8fd9\u4e2a\u67e5\u627e\u8fc7\u7a0b\u6240\u5168\u8868\u626b\u63cf\u3002\u6709\u5929DBA\u8bf4\u8fd9\u4e2a\u626b\u63cf\u592a\u6162\u4e86\uff0c\u770b\u770b\u8868\u91cc\u7684\u6570\u636e\u662f\u5f88\u5c11\u7684\u3002\u539f\u56e0\u5c31\u662f HWM \u5e26\u6765\u7684\u526f\u4f5c\u7528\u3002<\/p>\n<\/blockquote>\n<h3>\u8868\u8fde\u63a5<\/h3>\n<p>\u8868\u8fde\u63a5\u987a\u5e8f\uff1a\u4e0d\u7ba1\u76ee\u6807 SQL \u4e2d\u6709\u591a\u5c11\u4e2a\u8868\u505a\u8fde\u63a5\uff0cOracle \u5728\u5b9e\u9645\u6267\u884c\u8be5 SQL \u65f6\u90fd\u53ea\u80fd\u5148\u4e24\u4e24\u505a\u8868\u8fde\u63a5\uff0c\u518d\u4f9d\u6b21\u6267\u884c\u8fd9\u6837\u7684\u4e24\u4e24\u8868\u8fde\u63a5\uff0c\u76f4\u5230\u76ee\u6807 SQL \u4e2d\u6240\u6709\u8868\u90fd\u5df2\u505a\u8fde\u63a5\u5b8c\u6bd5\u3002<\/p>\n<p>\u5728 Oracle \u4e2d\u4e24\u4e2a\u8868\u4e4b\u95f4\u7684\u8868\u8fde\u63a5\u65b9\u6cd5\u6709  \u6392\u5e8f\u5408\u5e76\u8fde\u63a5\u3001\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u3001\u54c8\u5e0c\u8fde\u63a5\u548c\u7b1b\u5361\u5c14\u8fde\u63a5\u56db\u79cd\u3002<\/p>\n<h4>\u6392\u5e8f\u5408\u5e76\u8fde\u63a5<\/h4>\n<p>\u6b65\u9aa4\u4e3a\uff1a<\/p>\n<ol>\n<li>\u4ee5\u76ee\u6807 SQL \u4e2d\u6307\u5b9a\u7684\u8c13\u8bcd\u6761\u4ef6\uff08\u5982\u679c\u6709\uff09\u53bb\u8bbf\u95ee\u8868 T1\uff0c\u7136\u540e\u5bf9\u8bbf\u95ee\u7ed3\u679c\u6309\u7167 T1 \u7684\u8fde\u63a5\u5217\u8fdb\u884c\u6392\u5e8f\uff0c\u6392\u597d\u5e8f\u7684\u7ed3\u679c\u96c6\u4f5c\u4e3a\u7ed3\u679c\u96c6 1\uff1b   <\/li>\n<li>\u4ee5\u76ee\u6807 SQL \u4e2d\u7684\u6307\u5b9a\u8c13\u8bcd\u6761\u4ef6\uff08\u5982\u679c\u6709\uff09\u8bbf\u95ee\u8868 T2\uff0c\u5bf9\u8bbf\u95ee\u7ed3\u679c\u6309\u7167\u8868 T2 \u4e2d\u7684\u8fde\u63a5\u5217\u6392\u5e8f\uff0c\u4f5c\u4e3a\u7ed3\u679c\u96c62\uff1b   <\/li>\n<li>\u5bf9\u7ed3\u679c\u96c61\u548c\u7ed3\u679c\u96c62 \u8fdb\u884c\u5408\u5e76\u64cd\u4f5c\uff0c\u4ece\u4e2d\u53d6\u51fa\u5339\u914d\u6570\u636e\u4f5c\u4e3a\u6392\u5e8f\u5408\u5e76\u8fde\u63a5\u7684\u6700\u7ec8\u6267\u884c\u7ed3\u679c\u3002<\/li>\n<\/ol>\n<p>\u6392\u5e8f\u5408\u5e76\u8fde\u63a5\u7684\u6548\u7387\u8fdc\u4e0d\u5982\u54c8\u5e0c\u8fde\u63a5\uff0c\u4f46\u9002\u7528\u8303\u56f4\u66f4\u5e7f\u3002\u54c8\u5e0c\u8fde\u63a5\u901a\u5e38\u53ea\u80fd\u7528\u4e8e\u7b49\u503c\u8fde\u63a5\uff0c\u800c\u6392\u5e8f\u5408\u5e76\u8fde\u63a5\u8fd8\u80fd\u7528\u4e8e\u5176\u4ed6\u8fde\u63a5\u6761\u4ef6\uff08\u5982 <code>&lt;, &lt;=, &gt;,  &gt;=<\/code>\uff09\u3002<\/p>\n<p>\u901a\u5e38\uff0c\u6392\u5e8f\u5408\u5e76\u8fde\u63a5\u4e0d\u9002\u7528\u4e8e OLTP \u7cfb\u7edf\uff0c\u56e0\u4e3a\u5bf9\u4e8e OLTP \u7cfb\u7edf\u6392\u5e8f\u662f\u6602\u8d35\u7684\u64cd\u4f5c\u3002\u5982\u679c\u80fd\u907f\u514d\u6392\u5e8f\u64cd\u4f5c\uff0c\u5373\u4f7f\u662f OLTP \u7cfb\u7edf\u8fd8\u662f\u53ef\u4ee5\u7528\u6392\u5e8f\u5408\u5e76\u8fde\u63a5\u7684\u3002<\/p>\n<h4>\u5d4c\u5957\u5faa\u73af\u8fde\u63a5<\/h4>\n<p>\u6b65\u9aa4\u4e3a\uff1a<\/p>\n<ol>\n<li>\u4f18\u5316\u5668\u4f1a\u6309\u7167\u4e00\u5b9a\u7684\u89c4\u5219\u6765\u51b3\u5b9a\u8868 T1 \u548c T2 \u4e2d\u8c01\u662f\u9a71\u52a8\u8868\u3001\u8c01\u662f\u88ab\u9a71\u52a8\u8868\u3002\u9a71\u52a8\u8868\u7528\u4e8e\u5916\u5c42\u5faa\u73af\uff0c\u88ab\u9a71\u52a8\u8868\u7528\u4e8e\u5185\u5c42\u5faa\u73af\uff1b<\/li>\n<li>\u4ee5\u76ee\u6807 SQL \u4e2d\u6307\u5b9a\u7684\u8c13\u8bcd\u6761\u4ef6\uff08\u5982\u679c\u6709\uff09\u53bb\u8bbf\u95ee\u9a71\u52a8\u8868\uff0c\u5f97\u5230\u7ed3\u679c\u96c61\uff1b<\/li>\n<li>\u5bf9\u4e8e\u7ed3\u679c\u96c61 \u4e2d\u7684\u6bcf\u4e00\u6761\u8bb0\u5f55\uff0c\u6309\u7167\u8fde\u63a5\u6761\u4ef6\u53bb\u88ab\u9a71\u52a8\u8868\u67e5\u627e\u6ee1\u8db3\u6761\u4ef6\u7684\u8bb0\u5f55\u3002<\/li>\n<\/ol>\n<p>\u7ed3\u679c\u96c61 \u4e2d\u6709\u591a\u5c11\u6761\u8bb0\u5f55\uff0c\u5c31\u5f97\u53bb\u88ab\u9a71\u52a8\u8868\u67e5\u627e\u591a\u5c11\u6b21\u3002<\/p>\n<p>\u5982\u679c Oracle \u4f7f\u7528\u7684\u662f\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\uff0c\u4e14\u5728\u88ab\u9a71\u52a8\u8868\u7684\u8fde\u63a5\u5217\u4e0a\u5b58\u5728\u7d22\u5f15\uff0c\u90a3\u4e48 Oracle \u5728\u8bbf\u95ee\u8be5\u7d22\u5f15\u65f6\u901a\u5e38\u4f1a\u4f7f\u7528\u5355\u5757\u8bfb\uff0c\u8fd9\u610f\u5473\u7740\u9a71\u52a8\u7ed3\u679c\u96c6\u6709\u591a\u5c11\u6761\u8bb0\u5f55\u5c31\u5f97\u8bbf\u95ee\u8be5\u7d22\u5f15\u591a\u5c11\u6b21\u3002\u5982\u679c\u6240\u9700\u7684\u6570\u636e\u4e0d\u80fd\u4ece\u7d22\u5f15\u83b7\u5f97\uff0c\u8fd8\u5f97\u56de\u8868\uff0c\u8fd9\u4e2a\u56de\u8868\u64cd\u4f5c\u901a\u5e38\u4e5f\u662f\u5355\u5757\u8bfb\u3002<\/p>\n<p>\u5411\u91cfI\/O\uff1a\u4e3a\u4e86\u63d0\u9ad8\u5d4c\u5957\u5faa\u73af\u7684\u6267\u884c\u6548\u7387\uff0cOracle 11g \u5f15\u5165\u4e86\u5411\u91cfI\/O\u3002\u5f15\u5165\u5411\u91cfI\/O\u540e\uff0cOracle \u53ef\u4ee5\u5c06\u539f\u5148\u4e00\u6279\u5355\u5757\u8bfb\u6240\u9700\u8981\u8017\u8d39\u7684\u7269\u7406 I\/O \u7ec4\u5408\u8d77\u6765\uff0c\u7136\u540e\u7528\u4e00\u4e2a\u5411\u91cfI\/O \u53bb\u6279\u91cf\u5904\u7406\u5b83\u4eec\uff0c\u8fd9\u6837\u5c31\u5b9e\u73b0\u4e86\u5728\u5355\u5757\u8bfb\u7684\u6570\u91cf\u4e0d\u964d\u4f4e\u7684\u60c5\u51b5\u4e0b\u51cf\u5c11\u8fd9\u4e9b\u5355\u5757\u8bfb\u6240\u9700\u8981\u8017\u8d39\u7684\u7269\u7406 I\/O \u6570\u91cf\uff0c\u4e5f\u5c31\u63d0\u9ad8\u4e86\u5d4c\u5957\u5faa\u73af\u7684\u6548\u7387\u3002<\/p>\n<p>\u4f18\u7f3a\u70b9\uff1a<\/p>\n<ul>\n<li>\u5982\u679c\u9a71\u52a8\u8868\u6240\u5bf9\u5e94\u7684\u7ed3\u679c\u96c61\u7684\u8bb0\u5f55\u6570\u8f83\u5c11\uff0c\u4e14\u5728\u88ab\u9a71\u52a8\u8868\u7684\u8fde\u63a5\u5217\u4e0a\u53c8\u5b58\u5728\u552f\u4e00\u7d22\u5f15\uff08\u6216\u8005\u9009\u62e9\u6027\u5f88\u597d\u7684\u975e\u552f\u4e00\u7d22\u5f15\uff09\uff0c\u90a3\u4e48\u5d4c\u5957\u5faa\u73af\u7684\u6267\u884c\u6548\u7387\u5c31\u4f1a\u5f88\u9ad8\uff1b\u5982\u679c\u9a71\u52a8\u8868\u6240\u5bf9\u5e94\u7684\u7ed3\u679c\u96c6\u7684\u8bb0\u5f55\u6570\u5f88\u591a\uff0c\u5373\u4f7f\u88ab\u9a71\u52a8\u8868\u7684\u8fde\u63a5\u5217\u4e0a\u6709\u7d22\u5f15\uff0c\u6267\u884c\u6548\u7387\u4e5f\u4e0d\u4f1a\u5f88\u9ad8\u3002<\/li>\n<li>\u5bf9\u4e8e\u5927\u8868\u4f5c\u4e3a\u9a71\u52a8\u8868\uff0c\u6548\u7387\u53d6\u51b3\u4e8e\u8c13\u8bcd\u6761\u4ef6\u80fd\u5426\u5c06\u9a71\u52a8\u7ed3\u679c\u96c6\u7684\u6570\u636e\u91cf\u964d\u4e0b\u6765\u3002<\/li>\n<li>\u5d4c\u5957\u5faa\u73af\u6709\u4e00\u4e2a\u5176\u4ed6\u8fde\u63a5\u65b9\u6cd5\u6ca1\u6709\u7684\u4f18\u70b9\u662f\uff1a\u53ef\u4ee5\u5b9e\u73b0\u5feb\u901f\u54cd\u5e94\u3002<\/li>\n<\/ul>\n<h4>\u54c8\u5e0c\u8fde\u63a5<\/h4>\n<p>\u6b65\u9aa4\u4e3a\uff1a<\/p>\n<ol>\n<li><\/li>\n<li><\/li>\n<li><\/li>\n<\/ol>\n<p>\u4f18\u7f3a\u70b9\u53ca\u9002\u5e94\u573a\u666f\uff1a<\/p>\n<ul>\n<li>\u54c8\u5e0c\u8fde\u63a5\u4e0d\u4e00\u5b9a\u4f1a\u6392\u5e8f\uff0c\u5927\u591a\u6570\u60c5\u51b5\u4e0b\u4e0d\u9700\u8981\u6392\u5e8f\u3002<\/li>\n<li>\u54c8\u5e0c\u8fde\u63a5\u7684\u9a71\u52a8\u8868\u6240\u5bf9\u5e94\u7684\u8fde\u63a5\u5217\u7684\u9009\u62e9\u6027\u5e94\u5c3d\u53ef\u80fd\u597d\uff0c\u56e0\u4e3a\u8fd9\u4e2a\u9009\u62e9\u6027\u4f1a\u5f71\u54cd\u5bf9\u5e94\u7684 Hash Bucket \u4e2d\u7684\u8bb0\u5f55\u6570\uff0c\u800c Hash Bucket \u4e2d\u7684\u8bb0\u5f55\u6570\u53c8\u4f1a\u76f4\u63a5\u5f71\u54cd\u4ece\u8be5  Hash Bucket \u4e2d\u67e5\u627e\u54c1\u724c\u8bb0\u5f55\u7684\u6548\u7387\u3002**\u5982\u679c\u4e00\u4e2a  Hash Bucket \u91cc\u6240\u5305\u542b\u7684\u8bb0\u5f55\u6570\u8fc7\u591a\uff0c\u5219\u53ef\u80fd\u4f1a\u4e25\u91cd\u964d\u4f4e\u6240\u5bf9\u5e94\u54c8\u5e0c\u8fde\u63a5\u7684\u6267\u884c\u6548\u7387\uff0c\u6b64\u65f6\u5178\u578b\u7684\u8868\u73b0\u662f\u8be5\u54c8\u5e0c\u8fde\u63a5\u6267\u884c\u4e86\u5f88\u957f\u65f6\u95f4\u90fd\u6ca1\u6709\u7ed3\u675f\uff0c\u6570\u636e\u5e93\u6240\u5728\u670d\u52a1\u5668\u4e0a\u7684 CPU \u5360\u7528\u7387\u5f88\u9ad8\uff0c\u4f46\u76ee\u6807 SQL \u6240\u6d88\u8017\u7684\u903b\u8f91\u8bfb\u5f88\u4f4e\uff0c\u56e0\u4e3a\u6b64\u65f6\u5927\u90e8\u5206\u65f6\u95f4\u90fd\u8017\u8d39\u5728\u4e86\u904d\u5386\u4e0a\u8ff0 Hash Bucket \u91cc\u7684\u6240\u6709\u8bb0\u5f55\u4e0a\uff0c\u800c\u904d\u5386 Hash Bucket \u91cc\u7684\u8bb0\u5f55\u8fd9\u4e2a\u52a8\u4f5c\u53d1\u751f\u5728 PGA \u7684\u5de5\u4f5c\u533a\u91cc\uff0c\u6240\u4ee5\u4e0d\u8017\u8d39\u903b\u8f91\u8bfb\u3002<\/li>\n<li>\u54c8\u5e0c\u8fde\u63a5\u53ea\u9002\u7528\u4e8e CBO\uff0c\u4e5f\u53ea\u80fd\u7528\u4e8e\u7b49\u503c\u8fde\u63a5\u6761\u4ef6\u3002<\/li>\n<li>\u54c8\u5e0c\u8fde\u63a5\u5f88\u9002\u5408\u4e8e\u5c0f\u8868\u548c\u5927\u8868\u4e4b\u95f4\u505a\u8868\u8fde\u63a5\u4e14\u8fde\u63a5\u7ed3\u679c\u96c6\u7684\u8bb0\u5f55\u6570\u8f83\u591a\u7684\u60c5\u5f62\uff0c\u7279\u522b\u662f\u5c0f\u8868\u7684\u8fde\u63a5\u5217\u7684\u9009\u62e9\u6027\u975e\u5e38\u597d\u7684\u60c5\u5f62\uff0c\u8fd9\u65f6\u54c8\u5e0c\u8fde\u63a5\u7684\u6267\u884c\u65f6\u95f4\u5c31\u53ef\u4ee5\u8fd1\u4f3c\u770b\u4f5c\u6240\u548c\u5168\u8868\u626b\u63cf\u90a3\u4e2a\u5927\u8868\u6240\u8017\u8d39\u7684\u65f6\u95f4\u76f8\u5f53\u3002<\/li>\n<li>\u5f53\u4e24\u4e2a\u8868\u505a\u54c8\u5e0c\u8fde\u63a5\u65f6\uff0c\u5982\u679c\u5728\u65bd\u52a0\u91cc\u76ee\u6807 SQL \u4e2d\u6307\u5b9a\u7684\u8c13\u8bcd\u6761\u4ef6\u540e\u7684\u90fd\u7684\u6570\u636e\u91cf\u8f83\u5c0f\u7684\u90a3\u4e2a\u7ed3\u679c\u96c6\u6240\u5bf9\u5e94\u7684 Hash Table \u80fd\u591f\u5b8c\u5168\u5bb9\u7eb3\u5728\u5185\u5b58\u4e2d\uff08PGA \u7684\u5de5\u4f5c\u533a\uff09\uff0c\u5219\u6b64\u65f6\u7684\u54c8\u5e0c\u8fde\u63a5\u7684\u6267\u884c\u6548\u7387\u5f88\u9ad8\u3002<\/li>\n<\/ul>\n<h4>\u7b1b\u5361\u5c14\u8fde\u63a5<\/h4>\n<hr\/>\n<p>\u6b22\u8fce\u5173\u6ce8\u6211\u7684\u5fae\u4fe1\u516c\u4f17\u53f7: <strong>coderbee\u7b14\u8bb0<\/strong>\uff0c\u53ef\u4ee5\u66f4\u53ca\u65f6\u56de\u590d\u4f60\u7684\u8ba8\u8bba\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"258\" height=\"258\" src=\"https:\/\/coderbee.net\/wp-content\/uploads\/2019\/01\/coderbee-note.jpg\" class=\"alignnone size-full wp-image-1707\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>CBO \u76f8\u5173\u57fa\u7840 cardinality \uff1a\u6307\u5b9a\u7ed3\u679c\u96c6\u7684\u884c\u6570\uff0c\u5b9e\u9645\u4e0a\u8868\u793a\u5bf9\u76ee\u6807  &hellip; <a href=\"https:\/\/coderbee.net\/index.php\/db\/20150526\/1229\">\u7ee7\u7eed\u9605\u8bfb <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[99,218,219],"_links":{"self":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1229"}],"collection":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/comments?post=1229"}],"version-history":[{"count":5,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1229\/revisions"}],"predecessor-version":[{"id":1244,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1229\/revisions\/1244"}],"wp:attachment":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/media?parent=1229"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/categories?post=1229"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/tags?post=1229"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}