{"id":1143,"date":"2015-01-17T16:30:58","date_gmt":"2015-01-17T08:30:58","guid":{"rendered":"http:\/\/coderbee.net\/?p=1143"},"modified":"2015-01-21T23:38:40","modified_gmt":"2015-01-21T15:38:40","slug":"oracle-%e8%a1%a8%e8%bf%9e%e6%8e%a5%e7%b1%bb%e5%9e%8b-join-type","status":"publish","type":"post","link":"https:\/\/coderbee.net\/index.php\/db\/20150117\/1143","title":{"rendered":"oracle \u8868\u8fde\u63a5\u7c7b\u578b join type"},"content":{"rendered":"<p>Join \u662f\u4e00\u79cd\u8bd5\u56fe\u5c06\u4e24\u4e2a\u8868\u7ed3\u5408\u5728\u4e00\u8d77\u7684\u8c13\u8bcd\uff0c\u4e00\u6b21\u53ea\u80fd\u8fde\u63a5 2 \u4e2a\u8868\uff0c\u8868\u8fde\u63a5\u4e5f\u53ef\u4ee5\u88ab\u79f0\u4e3a\u8868\u5173\u8054\u3002Join \u8fc7\u7a0b\u7684\u5404\u4e2a\u6b65\u9aa4\u7ecf\u5e38\u662f\u4e32\u884c\u64cd\u4f5c\uff0c\u5373\u4f7f\u76f8\u5173\u7684 row source \u53ef\u4ee5\u88ab\u5e76\u884c\u8bbf\u95ee\uff0c\u4f46\u662f\u5728\u5c06\u8868\u4e2d\u7b26\u5408\u9650\u5236\u6761\u4ef6\u7684\u6570\u636e\u8bfb\u5165\u5230\u5185\u5b58\u5f62\u6210 row source \u540e\uff0cjoin \u7684\u5176\u5b83\u6b65\u9aa4\u4e00\u822c\u662f\u4e32\u884c\u7684\u3002<\/p>\n<p>row source  (\u8868)\u4e4b\u95f4\u7684\u8fde\u63a5\u987a\u5e8f\u5bf9\u4e8e\u67e5\u8be2\u7684\u6548\u7387\u6709\u975e\u5e38\u5927\u7684\u5f71\u54cd\u3002\u901a\u8fc7\u9996\u5148\u5b58\u53d6\u7279\u5b9a\u7684\u8868\uff0c\u5373\u5c06\u8be5\u8868\u4f5c\u4e3a\u9a71\u52a8\u8868\uff0c\u8fd9\u6837\u53ef\u4ee5\u5148\u5e94\u7528\u67d0\u4e9b\u9650\u5236\u6761\u4ef6\uff0c\u4ece\u800c\u5f97\u5230\u4e00\u4e2a\u8f83\u5c0f\u7684 row source\uff0c\u4f7f\u8fde\u63a5\u7684\u6548\u7387\u8f83\u9ad8\uff0c\u8fd9\u4e5f\u5c31\u662f\u6211\u4eec\u5e38\u8bf4\u7684\u8981\u5148\u6267\u884c\u9650\u5236\u6761\u4ef6\u7684\u539f\u56e0\u3002\u4e00\u822c\u662f\u5728\u5c06\u8868\u8bfb\u5165\u5185\u5b58\u65f6\uff0c\u5e94\u7528 where \u5b50\u53e5\u4e2d\u5bf9\u8be5\u8868\u7684\u9650\u5236\u6761\u4ef6\u3002<\/p>\n<p>\u6839\u636e 2 \u4e2a row source \u7684\u8fde\u63a5\u6761\u4ef6\u7684\u4e2d\u64cd\u4f5c\u7b26\u7684\u4e0d\u540c\uff0c\u53ef\u4ee5\u5c06\u8fde\u63a5\u5206\u4e3a\u7b49\u503c\u8fde\u63a5(\u5982 WHERE A.COL1 = B.COL2)\u3001\u975e\u7b49\u503c\u8fde\u63a5(WHERE A.COL1> B.COL2)\u3001\u5916\u8fde\u63a5(WHERE A.COL1= B.COL2+))\u3002<\/p>\n<p><!--more--><\/p>\n<h3>NESTED LOOP JOIN<\/h3>\n<p>\u8fd9\u4e2a\u8fde\u63a5\u65b9\u6cd5\u6709\u9a71\u52a8\u8868(\u5916\u90e8\u8868)\u7684\u6982\u5ff5\u3002\u5176\u5b9e\uff0c\u8be5\u8fde\u63a5\u8fc7\u7a0b\u5c31\u662f\u4e00\u4e2a 2 \u5c42\u5d4c\u5957\u5faa\u73af\uff0c\u6240\u4ee5\u5916\u5c42\u5faa\u73af\u7684\u6b21\u6570\u8d8a\u5c11\u8d8a\u597d\uff0c\u8fd9\u4e5f\u5c31\u662f\u6211\u4eec\u4e3a\u4ec0\u4e48\u5c06\u5c0f\u8868\u6216\u8fd4\u56de\u8f83\u5c0f row source \u7684\u8868\u4f5c\u4e3a\u9a71\u52a8\u8868(\u7528\u4e8e\u5916\u5c42\u5faa\u73af)\u7684\u7406\u8bba\u4f9d\u636e\u3002<\/p>\n<p>\u5728 NESTED LOOPS \u8fde\u63a5\u4e2d\uff0cOracle \u8bfb\u53d6 row source1 \u4e2d\u7684\u6bcf\u4e00\u884c\uff0c\u7136\u540e\u5728 row source2 \u4e2d\u68c0\u67e5\u662f\u5426\u6709\u5339\u914d\u7684\u884c\uff0c\u6240\u6709\u88ab\u5339\u914d\u7684\u884c\u90fd\u88ab\u653e\u5230\u7ed3\u679c\u96c6\u4e2d\uff0c\u7136\u540e\u5904\u7406 row source1 \u4e2d\u7684\u4e0b\u4e00\u884c\u3002\u8fd9\u4e2a\u8fc7\u7a0b\u4e00\u76f4\u7ee7\u7eed\uff0c\u76f4\u5230 row source1 \u4e2d\u7684\u6240\u6709\u884c\u90fd\u88ab\u5904\u7406\u3002\u8fd9\u662f\u4ece\u8fde\u63a5\u64cd\u4f5c\u4e2d\u53ef\u4ee5\u5f97\u5230\u7b2c\u4e00\u4e2a\u5339\u914d\u884c\u7684\u6700\u5feb\u7684\u65b9\u6cd5\u4e4b\u4e00\uff0c\u8fd9\u79cd\u7c7b\u578b\u7684\u8fde\u63a5\u53ef\u4ee5\u7528\u5728\u9700\u8981\u5feb\u901f\u54cd\u5e94\u7684\u8bed\u53e5\u4e2d\uff0c\u4ee5\u54cd\u5e94\u901f\u5ea6\u4e3a\u4e3b\u8981\u76ee\u6807\u3002<\/p>\n<p>\u5982\u679c driving row source (\u5916\u90e8\u8868)\u6bd4\u8f83\u5c0f\uff0c\u5e76\u4e14\u5728 inner row source (\u5185\u90e8\u8868)\u4e0a\u6709\u552f\u4e00\u7d22\u5f15\uff0c\u6216\u6709\u9ad8\u9009\u62e9\u6027\u975e\u552f\u4e00\u7d22\u5f15\u65f6\uff0c\u4f7f\u7528\u8fd9\u79cd\u65b9\u6cd5\u53ef\u4ee5\u5f97\u5230\u8f83\u597d\u7684\u6548\u7387\u3002NESTED LOOPS \u6709\u5176\u5b83\u8fde\u63a5\u65b9\u6cd5\u6ca1\u6709\u7684\u7684\u4e00\u4e2a\u4f18\u70b9\u662f\uff1a\u53ef\u4ee5\u5148\u8fd4\u56de\u5df2\u7ecf\u8fde\u63a5\u7684\u884c\uff0c\u800c\u4e0d\u5fc5\u7b49\u5f85\u6240\u6709\u7684\u8fde\u63a5\u64cd\u4f5c\u5904\u7406\u5b8c\u624d\u8fd4\u56de\u6570\u636e\uff0c\u8fd9\u53ef\u4ee5\u5b9e\u73b0\u5feb\u901f\u7684\u54cd\u5e94\u65f6\u95f4\u3002<\/p>\n<h3>HASH JOIN<\/h3>\n<p>\u8f83\u5c0f\u7684 row source \u88ab\u7528\u6765\u6784\u5efa hash table \u4e0e bitmap \uff0c\u7b2c 2 \u4e2a row source \u88ab\u7528\u6765\u88ab hashed\uff0c\u5e76\u4e0e\u7b2c\u4e00\u4e2a row source \u751f\u6210\u7684 hash table \u8fdb\u884c\u5339\u914d\uff0c\u4ee5\u4fbf\u8fdb\u884c\u8fdb\u4e00\u6b65\u7684\u8fde\u63a5\u3002Bitmap \u88ab\u7528\u6765\u4f5c\u4e3a\u4e00\u79cd\u6bd4\u8f83\u5feb\u7684\u67e5\u627e\u65b9\u6cd5\uff0c\u6765\u68c0\u67e5\u5728 hash table \u4e2d\u662f\u5426\u6709\u5339\u914d\u7684\u884c\u3002\u7279\u522b\u7684\uff0c\u5f53 hash table \u6bd4\u8f83\u5927\u800c\u4e0d\u80fd\u5168\u90e8\u5bb9\u7eb3\u5728\u5185\u5b58\u4e2d\u65f6\uff0c\u8fd9\u79cd\u67e5\u627e\u65b9\u6cd5\u66f4\u4e3a\u6709\u7528\u3002\u8fd9\u79cd\u8fde\u63a5\u65b9\u6cd5\u4e5f\u6709NL\u8fde\u63a5\u4e2d\u6240\u8c13\u7684\u9a71\u52a8\u8868\u7684\u6982\u5ff5\uff0c\u88ab\u6784\u5efa\u4e3a hash table \u4e0e bitmap \u7684\u8868\u4e3a\u9a71\u52a8\u8868\uff0c\u5f53\u88ab\u6784\u5efa\u7684 hash table \u4e0e bitmap \u80fd\u88ab\u5bb9\u7eb3\u5728\u5185\u5b58\u4e2d\u65f6\uff0c\u8fd9\u79cd\u8fde\u63a5\u65b9\u5f0f\u7684\u6548\u7387\u6781\u9ad8\u3002<\/p>\n<h3>SORT MERGE JOIN<\/h3>\n<p>\u5185\u90e8\u8fde\u63a5\u8fc7\u7a0b\uff1a<\/p>\n<ol>\n<li>\u9996\u5148\u751f\u6210 row source1 \u9700\u8981\u7684\u6570\u636e\uff0c\u7136\u540e\u5bf9\u8fd9\u4e9b\u6570\u636e\u6309\u7167\u8fde\u63a5\u64cd\u4f5c\u5173\u8054\u5217\u8fdb\u884c\u6392\u5e8f\u3002<\/li>\n<li>\u968f\u540e\u751f\u6210 row source2 \u9700\u8981\u7684\u6570\u636e\uff0c\u7136\u540e\u5bf9\u8fd9\u4e9b\u6570\u636e\u6309\u7167\u4e0e sort source1 \u5bf9\u5e94\u7684\u8fde\u63a5\u64cd\u4f5c\u5173\u8054\u5217\u8fdb\u884c\u6392\u5e8f\u3002<\/li>\n<li>\u6700\u540e\u4e24\u8fb9\u5df2\u6392\u5e8f\u7684\u884c\u88ab\u653e\u5728\u4e00\u8d77\u6267\u884c\u5408\u5e76\u64cd\u4f5c\uff0c\u5373\u5c06 2 \u4e2a row source \u6309\u7167\u8fde\u63a5\u6761\u4ef6\u8fde\u63a5\u8d77\u6765\u3002<\/li>\n<\/ol>\n<p>\u6392\u5e8f\u662f\u4e00\u4e2a\u8d39\u65f6\u3001\u8d39\u8d44\u6e90\u7684\u64cd\u4f5c\uff0c\u7279\u522b\u5bf9\u4e8e\u5927\u8868\u3002\u57fa\u4e8e\u8fd9\u4e2a\u539f\u56e0\uff0cSMJ \u7ecf\u5e38\u4e0d\u662f\u4e00\u4e2a\u7279\u522b\u6709\u6548\u7684\u8fde\u63a5\u65b9\u6cd5\uff0c\u4f46\u662f\u5982\u679c 2 \u4e2a row source \u90fd\u5df2\u7ecf\u9884\u5148\u6392\u5e8f\uff0c\u5219\u8fd9\u79cd\u8fde\u63a5\u65b9\u6cd5\u7684\u6548\u7387\u4e5f\u662f\u86ee\u9ad8\u7684\u3002<\/p>\n<h3>\u600e\u4e48\u9009\u62e9\u8fde\u63a5\u65b9\u6cd5<\/h3>\n<h4>\u6392\u5e8f &#8211; &#8211; \u5408\u5e76\u8fde\u63a5(Sort Merge Join, SMJ)\uff1a<\/h4>\n<p>\u5982\u679c\u5728\u5173\u8054\u7684\u5217\u4e0a\u90fd\u6709\u7d22\u5f15\uff0c\u90a3\u4e48\u6548\u7387\u4f1a\u6bd4\u8f83\u597d\uff0c\u56e0\u4e3a\u7701\u5374\u4e86\u6392\u5e8f\u7684\u6b65\u9aa4\u3002<\/p>\n<h4>\u5d4c\u5957\u5faa\u73af(Nested Loops, NL)\uff1a<\/h4>\n<ul>\n<li>\n<p>\u5982\u679c driving row source (\u5916\u90e8\u8868)\u6bd4\u8f83\u5c0f\uff0c\u5e76\u4e14\u5728 inner row source (\u5185\u90e8\u8868)\u4e0a\u6709\u552f\u4e00\u7d22\u5f15\uff0c\u6216\u6709\u9ad8\u9009\u62e9\u6027\u975e\u552f\u4e00\u7d22\u5f15\u65f6\uff0c\u4f7f\u7528\u8fd9\u79cd\u65b9\u6cd5\u53ef\u4ee5\u5f97\u5230\u8f83\u597d\u7684\u6548\u7387\u3002<\/p>\n<\/li>\n<li>\n<p>NESTED LOOPS \u6709\u5176\u5b83\u8fde\u63a5\u65b9\u6cd5\u6ca1\u6709\u7684\u7684\u4e00\u4e2a\u4f18\u70b9\u662f\uff1a\u53ef\u4ee5\u5148\u8fd4\u56de\u5df2\u7ecf\u8fde\u63a5\u7684\u884c\uff0c\u800c\u4e0d\u5fc5\u7b49\u5f85\u6240\u6709\u7684\u8fde\u63a5\u64cd\u4f5c\u5904\u7406\u5b8c\u624d\u8fd4\u56de\u6570\u636e\uff0c\u8fd9\u53ef\u4ee5\u5b9e\u73b0\u5feb\u901f\u7684\u54cd\u5e94\u65f6\u95f4\u3002<\/p>\n<\/li>\n<\/ul>\n<h4>\u54c8\u5e0c\u8fde\u63a5(Hash Join, HJ)\uff1a<\/h4>\n<ul>\n<li>\n<p>\u8fd9\u79cd\u65b9\u6cd5\u662f\u5728oracle7\u540e\u6765\u5f15\u5165\u7684\uff0c\u4f7f\u7528\u4e86\u6bd4\u8f83\u5148\u8fdb\u7684\u8fde\u63a5\u7406\u8bba\uff0c\u4e00\u822c\u6765\u8bf4\uff0c\u5176\u6548\u7387\u5e94\u8be5\u597d\u4e8e\u5176\u5b832\u79cd\u8fde\u63a5\uff0c\u4f46\u662f\u8fd9\u79cd\u8fde\u63a5\u53ea\u80fd\u7528\u5728 CBO \u4f18\u5316\u5668\u4e2d\u3002<\/p>\n<\/li>\n<li>\n<p>\u5728 2 \u4e2a\u8f83\u5927\u7684 row source \u4e4b\u95f4\u8fde\u63a5\u65f6\u4f1a\u53d6\u5f97\u76f8\u5bf9\u8f83\u597d\u7684\u6548\u7387\uff0c\u5728\u4e00\u4e2a row source \u8f83\u5c0f\u65f6\u5219\u80fd\u53d6\u5f97\u66f4\u597d\u7684\u6548\u7387\u3002<\/p>\n<\/li>\n<li>\n<p>\u53ea\u80fd\u7528\u4e8e\u7b49\u503c\u8fde\u63a5\u4e2d\u3002<\/p>\n<\/li>\n<\/ul>\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>Join \u662f\u4e00\u79cd\u8bd5\u56fe\u5c06\u4e24\u4e2a\u8868\u7ed3\u5408\u5728\u4e00\u8d77\u7684\u8c13\u8bcd\uff0c\u4e00\u6b21\u53ea\u80fd\u8fde\u63a5 2 \u4e2a\u8868\uff0c\u8868\u8fde\u63a5\u4e5f\u53ef &hellip; <a href=\"https:\/\/coderbee.net\/index.php\/db\/20150117\/1143\">\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":[99,211],"_links":{"self":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1143"}],"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=1143"}],"version-history":[{"count":2,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1143\/revisions"}],"predecessor-version":[{"id":1145,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/posts\/1143\/revisions\/1145"}],"wp:attachment":[{"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/media?parent=1143"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/categories?post=1143"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/coderbee.net\/index.php\/wp-json\/wp\/v2\/tags?post=1143"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}