Oracle<\/a>\u512a\u5316\u5668\u7684\u512a\u5316\u65b9\u5f0f<\/p>\n\u3000\u3000Oracle\u512a\u5316\u5668\u5171\u6709\u5169\u7a2e\u7684\u512a\u5316\u65b9\u5f0f,\u5373\u57fa\u65bc\u898f\u5247\u7684\u512a\u5316\u65b9\u5f0f(Rule-Based Optimization,\u7c21\u7a31\u70baRBO)\u548c\u57fa\u65bc\u4ee3\u50f9\u7684\u512a\u5316\u65b9\u5f0f(Cost-Based Optimization,\u7c21\u7a31\u70baCBO)\u3002<\/p>\n
\u3000\u3000A\u3001RBO\u65b9\u5f0f\uff1a\u512a\u5316\u5668\u5728\u5206\u6790SQL\u8a9e\u53e5\u6642,\u6240\u9075\u5faa\u7684\u662fOracle\u5167\u90e8\u9810\u5b9a\u7684\u58f9\u4e9b\u898f\u5247\u3002\u6bd4\u5982\u6211\u5011\u5e38\u898b\u7684,\u7576\u58f9\u500bwhere\u5b50\u53e5\u4e2d\u7684\u58f9\u5217\u6709\u7d22\u5f15\u6642\u53bb\u8d70\u7d22\u5f15\u3002<\/p>\n
\u3000\u3000B\u3001CBO\u65b9\u5f0f\uff1a\u4f9d\u8a5e\u7fa9\u53ef\u77e5,\u5b83\u662f\u770b\u8a9e\u53e5\u7684\u4ee3\u50f9(Cost)\u4e86,\u9019\u88cf\u7684\u4ee3\u50f9\u4e3b\u8981\u6307Cpu\u548c\u5167\u5b58\u3002\u512a\u5316\u5668\u5728\u5224\u65b7\u662f\u5426\u7528\u9019\u7a2e\u65b9\u5f0f\u6642,\u4e3b\u8981\u53c3\u7167\u7684\u662f\u8868\u53ca\u7d22\u5f15\u7684\u7d71\u8a08\u4fe1\u606f\u3002\u7d71\u8a08\u4fe1\u606f\u7d66\u51fa\u8868\u7684\u5927\u5c0f \u3001\u6709\u5c11\u884c\u3001\u6bcf\u884c\u7684\u9577\u5ea6\u7b49\u4fe1\u606f\u3002\u9019\u4e9b\u7d71\u8a08\u4fe1\u606f\u8d77\u521d\u5728\u5eab\u5167\u662f\u6c92\u6709\u7684,\u662f\u59b3\u5728\u505aanalyze\u5f8c\u624d\u51fa\u73fe\u7684,\u5f88\u591a\u7684\u6642\u4faf\u904e\u671f\u7d71\u8a08\u4fe1\u606f\u6703\u4ee4\u512a\u5316\u5668\u505a\u51fa\u58f9\u500b\u932f\u8aa4\u7684\u57f7\u884c\u8a08\u5283,\u56e0\u4e9b\u6211\u5011\u61c9\u53ca\u6642\u66f4\u65b0\u9019\u4e9b\u4fe1\u606f\u3002\u5728Oracle8\u53ca\u4ee5\u5f8c\u7684\u7248\u672c,Oracle\u5217\u63a8\u85a6\u7528CBO\u7684\u65b9\u5f0f\u3002<\/p>\n
\u3000\u3000\u6211\u5011\u8981\u660e\u4e86,\u4e0d\u58f9\u5b9a\u8d70\u7d22\u5f15\u5c31\u662f\u512a\u7684 ,\u6bd4\u5982\u58f9\u500b\u8868\u53ea\u6709\u5169\u884c\u6578\u64da,\u58f9\u6b21IO\u5c31\u53ef\u4ee5\u5b8c\u6210\u5168\u8868\u7684\u6aa2\u7d22,\u800c\u6b64\u6642\u8d70\u7d22\u5f15\u6642\u5247\u9700\u8981\u5169\u6b21IO,\u9019\u6642\u5c0d\u9019\u500b\u8868\u505a\u5168\u8868\u6383\u63cf(full table scan)\u662f\u6700\u597d\u7684\u3002<\/p>\n
\u3000\u30002\u3001Oracle\u512a\u5316\u5668\u7684\u512a\u5316\u6a21\u5f0f(Optermizer Mode)<\/p>\n
\u3000\u3000\u512a\u5316\u6a21\u5f0f\u5305\u62ecRule,Choose,First rows,All rows\u9019\u56db\u7a2e\u65b9\u5f0f,\u4e5f\u5c31\u662f\u6211\u5011\u4ee5\u4e0a\u6240\u63d0\u53ca\u7684\u3002\u5982\u4e0b\u6211\u89e3\u91cb\u58f9\u4e0b\uff1a<\/p>\n
\u3000\u3000Rule:\u4e0d\u7528\u591a\u8aaa,\u5373\u8d70\u57fa\u65bc\u898f\u5247\u7684\u65b9\u5f0f\u3002<\/p>\n
\u3000\u3000Choolse:\u9019\u662f\u6211\u5011\u61c9\u89c0\u8a3b\u7684,\u9ed8\u8a8d\u7684\u60c5\u6cc1\u4e0bOracle\u7528\u7684\u4fbf\u662f\u9019\u7a2e\u65b9\u5f0f\u3002\u6307\u7684\u662f\u7576\u58f9\u500b\u8868\u6216\u6216\u7d22\u5f15\u6709\u7d71\u8a08\u4fe1\u606f,\u5247\u8d70CBO\u7684\u65b9\u5f0f,\u5982\u679c\u8868\u6216\u7d22\u5f15\u6c92\u7d71\u8a08\u4fe1\u606f,\u8868\u53c8\u4e0d\u662f\u7279\u5225\u7684\u5c0f,\u800c\u4e14\u76f8\u61c9\u7684\u5217\u6709\u7d22\u5f15\u6642,\u90a3\u9ebd\u5c31\u8d70\u7d22\u5f15,\u8d70RBO\u7684\u65b9\u5f0f\u3002<\/p>\n
\u3000\u3000First Rows:\u5b83\u8207Choose\u65b9\u5f0f\u662f\u985e\u4f3c\u7684,\u6240\u4e0d\u540c\u7684\u662f\u7576\u58f9\u500b\u8868\u6709\u7d71\u8a08\u4fe1\u606f\u6642,\u5b83\u5c07\u662f\u4ee5\u6700\u5feb\u7684\u65b9\u5f0f\u8fd4\u56de\u67e5\u8a62\u7684\u6700\u5148\u7684\u5e7e\u884c,\u5f9e\u7e3d\u9ad4\u4e0a\u6e1b\u5c11\u4e86\u97ff\u61c9\u6642\u9593\u3002<\/p>\n
\u3000\u3000All Rows:\u4e5f\u5c31\u662f\u6211\u5011\u6240\u8aaa\u7684Cost\u7684\u65b9\u5f0f,\u7576\u58f9\u500b\u8868\u6709\u7d71\u8a08\u4fe1\u606f\u6642,\u5b83\u5c07\u4ee5\u6700\u5feb\u7684\u65b9\u5f0f\u8fd4\u56de\u8868\u7684\u6240\u6709\u7684\u884c,\u5f9e\u7e3d\u9ad4\u4e0a\u63d0\u9ad8\u67e5\u8a62\u7684\u541e\u5410\u91cf\u3002\u6c92\u6709\u7d71\u8a08\u4fe1\u606f\u5247\u8d70\u57fa\u65bc\u898f\u5247\u7684\u65b9\u5f0f\u3002<\/p>\n
\u3000\u30003\u3001\u5982\u4f55\u8a2d\u5b9a\u9078\u7528\u54ea\u7a2e\u512a\u5316\u6a21\u5f0f<\/p>\n
\u3000\u3000\u25c6A\u3001Instance\u7d1a\u5225<\/p>\n
\u3000\u3000\u6211\u5011\u53ef\u4ee5\u901a\u904e\u5728init.ora\u6587\u4ef6\u4e2d\u8a2d\u5b9aOPTIMIZER_MODE=RULE\u3001OPTIMIZER_MODE=CHOOSE\u3001OPTIMIZER_MODE=FIRST_ROWS\u3001OPTIMIZER_MODE=ALL_ROWS\u53bb\u9078\u75283\u6240\u63d0\u7684\u56db\u7a2e\u65b9\u5f0f,\u5982\u679c\u59b3\u6c92\u8a2d\u5b9aOPTIMIZER_MODE\u53c3\u6578\u5247\u9ed8\u8a8d\u7528\u7684\u662fChoose\u9019\u7a2e\u65b9\u5f0f\u3002<\/p>\n
\u3000\u3000\u25c6B\u3001Sessions\u7d1a\u5225<\/p>\n
\u3000\u3000\u901a\u904eSQL> ALTER SESSION SET OPTIMIZER_MODE=;\u4f86\u8a2d\u5b9a\u3002<\/p>\n
\u3000\u3000\u25c6C\u3001\u8a9e\u53e5\u7d1a\u5225<\/p>\n
\u3000\u3000\u9019\u4e9b\u9700\u8981\u7528\u5230Hint<\/p>\n","protected":false},"excerpt":{"rendered":"
\u4e0d\u540c\u7684\u60c5\u6cc1,\u58f9\u689dSQL\u53ef\u80fd\u6709\u591a\u7a2e\u57f7\u884c\u8a08\u5283,\u4f46\u5728\u67d0\u58f9\u6642\u9ede,\u58f9\u5b9a\u53ea\u6709\u58f9\u7a2e\u57f7\u884c\u8a08\u5283\u662f\u6700\u512a\u7684,\u82b1\u8cbb\u6642\u9593\u662f\u6700\u5c11\u7684\u3002\u76f8\u4fe1\u59b3 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[2748,494,495],"class_list":["post-1348","post","type-post","status-publish","format-standard","hentry","category-oracle","tag-oracle","tag-494","tag-495"],"_links":{"self":[{"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/posts\/1348","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/comments?post=1348"}],"version-history":[{"count":0,"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/posts\/1348\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/media?parent=1348"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/categories?post=1348"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.killtest.hk\/index.php\/wp-json\/wp\/v2\/tags?post=1348"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}