{"id":5385,"date":"2020-07-30T00:04:54","date_gmt":"2020-07-29T16:04:54","guid":{"rendered":"http:\/\/39.97.231.10\/?p=5385"},"modified":"2020-07-30T00:04:54","modified_gmt":"2020-07-29T16:04:54","slug":"mysql-8-0-%e7%b4%a2%e5%bc%95%e8%b7%b3%e8%b7%83%e6%89%ab%e6%8f%8findex-skip-scan","status":"publish","type":"post","link":"http:\/\/www.weijing.co\/?p=5385","title":{"rendered":"MySQL 8.0 \u7d22\u5f15\u8df3\u8dc3\u626b\u63cf(Index Skip Scan)"},"content":{"rendered":"<div>\n<div>\n<div>\nMySQL 8.0.13 \u7248\u672c\u5bf9\u4e8erange\u67e5\u8be2\uff0c\u5f15\u5165\u4e86\u7d22\u5f15\u8df3\u8dc3\u626b\u63cf\uff08Index Skip Scan\uff09\u4f18\u5316\uff0c\u652f\u6301\u4e0d\u7b26\u5408\u7ec4\u5408\u7d22\u5f15\u6700\u5de6\u524d\u7f00\u539f\u5219\u6761\u4ef6\u4e0b\u7684SQL\uff0c\u4f9d\u7136\u80fd\u591f\u4f7f\u7528\u7ec4\u5408\u7d22\u5f15\uff0c\u51cf\u5c11\u4e0d\u5fc5\u8981\u7684\u626b\u63cf\u3002<br \/>\n\u5148\u770b\u4e00\u4e0b\u5b98\u65b9\u6587\u6863\u4e2d\u7ed9\u51fa\u7684\u573a\u666f\uff1a<\/p>\n<pre>CREATE TABLE t1 (f1 INT NOT NULL, f2 INT NOT NULL, PRIMARY KEY(f1, f2));\nINSERT INTO t1 VALUES\n  (1,1), (1,2), (1,3), (1,4), (1,5),\n  (2,1), (2,2), (2,3), (2,4), (2,5);\nINSERT INTO t1 SELECT f1, f2 + 5 FROM t1;\nINSERT INTO t1 SELECT f1, f2 + 10 FROM t1;\nINSERT INTO t1 SELECT f1, f2 + 20 FROM t1;\nINSERT INTO t1 SELECT f1, f2 + 40 FROM t1;\nANALYZE TABLE t1;\nEXPLAIN SELECT f1, f2 FROM t1 WHERE f2 &gt; 40;\n<\/pre>\n<p>t1\u8868\uff0c\u6709\u4e00\u4e2a\u8054\u5408\u7d22\u5f15 (f1,f2)\uff0c\u67e5\u8be2t2\u8868\uff0cwhere \u6761\u4ef6\u4e3a f2 &gt; 40<\/p>\n<ul>\n<li>MySQL 5.7.19\uff0c\u6267\u884c\u8ba1\u5212Extra\u5b57\u6bb5\u4e3a\uff1aUsing where; Using index<\/li>\n<li>MySQL 8.0.20\uff0c\u6267\u884c\u8ba1\u5212Extra\u5b57\u6bb5\u4e3a\uff1aUsing where; Using index for skip scan<\/li>\n<\/ul>\n<p>\u5728 MySQL 5.7 \u7248\u672c\uff0c\u4e0a\u8ff0SQL\u7684\u6267\u884c\u4e3b\u8981\u903b\u8f91\u662f\u4ece\u7d22\u5f15\u4e2d\u53d6\u51fa\u6240\u6709\u7684\u8bb0\u5f55\uff0c\u7136\u540e\u6309\u7167where\u6761\u4ef6f2&gt;40\u8fdb\u884c\u8fc7\u6ee4\uff0c\u6700\u540e\u5c06\u7ed3\u679c\u8fd4\u56de\u3002<br \/>\n\u5728MySQL 8.0 \u7248\u672c\uff0c\u4e0a\u8ff0SQL\u4f7f\u7528\u7d22\u5f15range\u626b\u63cf\uff0c\u4ee3\u66ff\u5168\u7d22\u5f15\u626b\u63cf\uff0c\u5bf9\u4e8e\u6bcf\u4e00\u4e2af1\u5b57\u6bb5\u7684\u503c\uff0c\u8fdb\u884cf2\u8303\u56f4\u626b\u63cf\u3002<br \/>\n\u5bf9\u4e8e\u4e0a\u8ff0\u5b98\u65b9\u6587\u6863\u7ed9\u51fa\u7684\u4f8b\u5b50\uff0c8.0\u7248\u672cSQL\u6267\u884c\u8fc7\u7a0b\u5982\u4e0b\uff1a<\/p>\n<ol>\n<li>\u83b7\u53d6f1\u5b57\u6bb5\u7b2c\u4e00\u4e2a\u552f\u4e00\u503c\uff0c\u4e5f\u5c31\u662ff1=1<\/li>\n<li>\u6784\u9020f1=1 and f2 &gt; 40\uff0c\u8fdb\u884c\u8303\u56f4\u67e5\u8be2<\/li>\n<li>\u83b7\u53d6f1\u5b57\u6bb5\u7b2c\u4e8c\u4e2a\u552f\u4e00\u503c\uff0c\u4e5f\u5c31\u662ff1=2<\/li>\n<li>\u6784\u9020f1=2 and f2 &gt; 40\uff0c\u8fdb\u884c\u8303\u56f4\u67e5\u8be2<\/li>\n<li>\u4e00\u76f4\u626b\u63cf\u5b8cf1\u5b57\u6bb5\u6240\u6709\u7684\u552f\u4e00\u503c\uff0c\u6700\u540e\u5c06\u7ed3\u679c\u5408\u5e76\u8fd4\u56de<\/li>\n<\/ol>\n<p>MySQL 8.0 \u4f7f\u7528\u8fd9\u79cd\u7b56\u7565\u4f1a\u51cf\u5c11\u8bbf\u95ee\u7684\u884c\u6570\uff0c\u56e0\u4e3a\u4f1a\u8df3\u8fc7\u4e0d\u7b26\u5408\u6784\u9020\u8303\u56f4\u7684\u884c\u3002<br \/>\nIndex Skip Scan\u9650\u5236\u6761\u4ef6\uff1a<\/p>\n<ol>\n<li>\u67e5\u8be2\u53ea\u80fd\u6d89\u53ca\u4e00\u5f20\u8868\uff0c\u591a\u8868\u5173\u8054\u65e0\u6cd5\u4f7f\u7528\u8be5\u7279\u6027<\/li>\n<li>\u67e5\u8be2SQL\u4e0d\u80fd\u4f7f\u7528 GROUP BY\u00a0\u6216\u8005\u00a0DISTINCT\u5b50\u53e5<\/li>\n<li>\u67e5\u8be2\u5b57\u6bb5\u5fc5\u987b\u662f\u7d22\u5f15\u4e2d\u7684\u5b57\u6bb5<\/li>\n<li>\u7ec4\u5408\u7d22\u5f15\u5f62\u5f0f\uff1a([A_1, \u2026, A_k,] B_1, \u2026, B_m, C [, D_1, \u2026, D_n])\uff0cA\uff0cD \u53ef\u4ee5\u4e3a\u7a7a\uff0c\u4f46\u662fB ,C \u4e0d\u80fd\u4e3a\u7a7a<\/li>\n<\/ol>\n<p>\u53c2\u6570\u5f00\u5173\uff1a<br \/>\n\u901a\u8fc7\u8bbe\u7f6e\u53c2\u6570optimizer_switch\u4e2d\u7684skip_scan=on\/off\uff0c\u6765\u63a7\u5236\u662f\u5426\u6253\u5f00\u8be5\u4f18\u5316\u7b56\u7565\uff0c\u9ed8\u8ba4\u6253\u5f00\u3002\n<\/p><\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>MySQL 8.0.13 \u7248\u672c\u5bf9\u4e8erange\u67e5\u8be2\uff0c\u5f15\u5165\u4e86\u7d22\u5f15\u8df3\u8dc3\u626b\u63cf\uff08Index Skip Scan\uff09\u4f18\u5316\uff0c\u652f &hellip;<\/p>\n<p class=\"read-more\"> <a class=\"\" href=\"http:\/\/www.weijing.co\/?p=5385\"> <span class=\"screen-reader-text\">MySQL 8.0 \u7d22\u5f15\u8df3\u8dc3\u626b\u63cf(Index Skip Scan)<\/span> \u67e5\u770b\u5168\u6587 &raquo;<\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"default","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":""},"categories":[90,88],"tags":[],"uagb_featured_image_src":{"full":false,"thumbnail":false,"medium":false,"medium_large":false,"large":false,"1536x1536":false,"2048x2048":false,"mailpoet_newsletter_max":false,"woocommerce_thumbnail":false,"woocommerce_single":false,"woocommerce_gallery_thumbnail":false,"shop_catalog":false,"shop_single":false,"shop_thumbnail":false},"uagb_author_info":{"display_name":"weijing","author_link":"http:\/\/www.weijing.co\/?author=4"},"uagb_comment_info":0,"uagb_excerpt":"MySQL 8.0.13 \u7248\u672c\u5bf9\u4e8erange\u67e5\u8be2\uff0c\u5f15\u5165\u4e86\u7d22\u5f15\u8df3\u8dc3\u626b\u63cf\uff08Index Skip Scan\uff09\u4f18\u5316\uff0c\u652f&hellip;","_links":{"self":[{"href":"http:\/\/www.weijing.co\/index.php?rest_route=\/wp\/v2\/posts\/5385"}],"collection":[{"href":"http:\/\/www.weijing.co\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.weijing.co\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.weijing.co\/index.php?rest_route=\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"http:\/\/www.weijing.co\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5385"}],"version-history":[{"count":0,"href":"http:\/\/www.weijing.co\/index.php?rest_route=\/wp\/v2\/posts\/5385\/revisions"}],"wp:attachment":[{"href":"http:\/\/www.weijing.co\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5385"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.weijing.co\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5385"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.weijing.co\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5385"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}