{"id":77556,"date":"2024-10-16T10:52:24","date_gmt":"2024-10-16T02:52:24","guid":{"rendered":"https:\/\/server.hk\/cnblog\/77556\/"},"modified":"2024-10-16T10:52:24","modified_gmt":"2024-10-16T02:52:24","slug":"mysql%e6%ba%90%e7%a2%bc%e5%ad%b8%e7%bf%92%ef%bc%9amdl%e5%ad%97%e5%85%b8%e9%8e%96","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/77556\/","title":{"rendered":"MySQL\u6e90\u78bc\u5b78\u7fd2\uff1aMDL\u5b57\u5178\u9396"},"content":{"rendered":"<h1 id=\"mysql%e6%ba%90%e7%a2%bc%e5%ad%b8%e7%bf%92%ef%bc%9amdl%e5%ad%97%e5%85%b8%e9%8e%96-NaloaYxEec\">MySQL\u6e90\u78bc\u5b78\u7fd2\uff1aMDL\u5b57\u5178\u9396<\/h1>\n<p>\u5728MySQL\u7684\u6e90\u78bc\u4e2d\uff0cMDL\uff08Metadata Lock\uff09\u5b57\u5178\u9396\u662f\u4e00\u500b\u91cd\u8981\u7684\u7d44\u4ef6\uff0c\u8ca0\u8cac\u7ba1\u7406\u5c0d\u6578\u64da\u5eab\u5143\u6578\u64da\u7684\u8a2a\u554f\u3002MDL\u7684\u8a2d\u8a08\u65e8\u5728\u78ba\u4fdd\u6578\u64da\u5eab\u64cd\u4f5c\u7684\u5b89\u5168\u6027\u548c\u4e00\u81f4\u6027\uff0c\u7279\u5225\u662f\u5728\u591a\u7528\u6236\u74b0\u5883\u4e2d\u3002\u672c\u6587\u5c07\u6df1\u5165\u63a2\u8a0eMDL\u5b57\u5178\u9396\u7684\u5de5\u4f5c\u539f\u7406\u3001\u4f7f\u7528\u5834\u666f\u53ca\u5176\u5728MySQL\u4e2d\u7684\u5be6\u73fe\u65b9\u5f0f\u3002<\/p>\n<h2 id=\"mdl%e5%ad%97%e5%85%b8%e9%8e%96%e7%9a%84%e5%9f%ba%e6%9c%ac%e6%a6%82%e5%bf%b5-NaloaYxEec\">MDL\u5b57\u5178\u9396\u7684\u57fa\u672c\u6982\u5ff5<\/h2>\n<p>MDL\u5b57\u5178\u9396\u7684\u4e3b\u8981\u529f\u80fd\u662f\u9632\u6b62\u540c\u6642\u5c0d\u6578\u64da\u5eab\u5143\u6578\u64da\u7684\u885d\u7a81\u8a2a\u554f\u3002\u7576\u4e00\u500b\u4e8b\u52d9\u9700\u8981\u8a2a\u554f\u67d0\u500b\u8868\u6216\u6578\u64da\u5eab\u7684\u5143\u6578\u64da\u6642\uff0cMDL\u6703\u70ba\u8a72\u5143\u6578\u64da\u52a0\u9396\uff0c\u5f9e\u800c\u9632\u6b62\u5176\u4ed6\u4e8b\u52d9\u5728\u6b64\u671f\u9593\u5c0d\u5176\u9032\u884c\u4fee\u6539\u3002\u9019\u6a23\u7684\u8a2d\u8a08\u53ef\u4ee5\u6709\u6548\u907f\u514d\u6578\u64da\u4e0d\u4e00\u81f4\u7684\u554f\u984c\u3002<\/p>\n<h2 id=\"mdl%e5%ad%97%e5%85%b8%e9%8e%96%e7%9a%84%e5%b7%a5%e4%bd%9c%e6%b5%81%e7%a8%8b-NaloaYxEec\">MDL\u5b57\u5178\u9396\u7684\u5de5\u4f5c\u6d41\u7a0b<\/h2>\n<p>MDL\u5b57\u5178\u9396\u7684\u5de5\u4f5c\u6d41\u7a0b\u53ef\u4ee5\u5206\u70ba\u4ee5\u4e0b\u5e7e\u500b\u6b65\u9a5f\uff1a<\/p>\n<ul>\n<li><strong>\u8acb\u6c42\u9396\u5b9a\uff1a<\/strong>\u7576\u4e00\u500b\u4e8b\u52d9\u9700\u8981\u8a2a\u554f\u67d0\u500b\u8868\u7684\u5143\u6578\u64da\u6642\uff0c\u5b83\u6703\u5411MDL\u8acb\u6c42\u9396\u5b9a\u3002<\/li>\n<li><strong>\u9396\u5b9a\u6aa2\u67e5\uff1a<\/strong>MDL\u6703\u6aa2\u67e5\u7576\u524d\u662f\u5426\u6709\u5176\u4ed6\u4e8b\u52d9\u6301\u6709\u8a72\u5143\u6578\u64da\u7684\u9396\u5b9a\u3002\u5982\u679c\u6c92\u6709\uff0c\u5247\u5141\u8a31\u8a72\u4e8b\u52d9\u7372\u5f97\u9396\u5b9a\u3002<\/li>\n<li><strong>\u9396\u5b9a\u6388\u4e88\uff1a<\/strong>\u4e00\u65e6\u9396\u5b9a\u88ab\u6388\u4e88\uff0c\u8a72\u4e8b\u52d9\u5c31\u53ef\u4ee5\u5b89\u5168\u5730\u8a2a\u554f\u548c\u64cd\u4f5c\u5143\u6578\u64da\u3002<\/li>\n<li><strong>\u9396\u5b9a\u91cb\u653e\uff1a<\/strong>\u7576\u4e8b\u52d9\u5b8c\u6210\u5f8c\uff0cMDL\u6703\u91cb\u653e\u9396\u5b9a\uff0c\u5141\u8a31\u5176\u4ed6\u4e8b\u52d9\u8a2a\u554f\u8a72\u5143\u6578\u64da\u3002<\/li>\n<\/ul>\n<h2 id=\"mdl%e5%ad%97%e5%85%b8%e9%8e%96%e7%9a%84%e9%a1%9e%e5%9e%8b-NaloaYxEec\">MDL\u5b57\u5178\u9396\u7684\u985e\u578b<\/h2>\n<p>MDL\u5b57\u5178\u9396\u4e3b\u8981\u6709\u5169\u7a2e\u985e\u578b\uff1a<\/p>\n<ul>\n<li><strong>\u5171\u4eab\u9396\uff08Shared Lock\uff09\uff1a<\/strong>\u5141\u8a31\u591a\u500b\u4e8b\u52d9\u540c\u6642\u8b80\u53d6\u5143\u6578\u64da\uff0c\u4f46\u4e0d\u5141\u8a31\u4fee\u6539\u3002<\/li>\n<li><strong>\u6392\u4ed6\u9396\uff08Exclusive Lock\uff09\uff1a<\/strong>\u53ea\u5141\u8a31\u4e00\u500b\u4e8b\u52d9\u8a2a\u554f\u5143\u6578\u64da\uff0c\u4e26\u4e14\u7981\u6b62\u5176\u4ed6\u4e8b\u52d9\u7684\u8b80\u53d6\u548c\u4fee\u6539\u3002<\/li>\n<\/ul>\n<h2 id=\"mdl%e5%ad%97%e5%85%b8%e9%8e%96%e7%9a%84%e5%af%a6%e7%8f%be-NaloaYxEec\">MDL\u5b57\u5178\u9396\u7684\u5be6\u73fe<\/h2>\n<p>\u5728MySQL\u7684\u6e90\u78bc\u4e2d\uff0cMDL\u5b57\u5178\u9396\u7684\u5be6\u73fe\u4e3b\u8981\u96c6\u4e2d\u5728\u4ee5\u4e0b\u5e7e\u500b\u6587\u4ef6\u4e2d\uff1a<\/p>\n<ul>\n<li><code>mdl.cc<\/code>\uff1a\u5305\u542bMDL\u7684\u4e3b\u8981\u908f\u8f2f\u548c\u9396\u5b9a\u7ba1\u7406\u3002<\/li>\n<li><code>mdl.h<\/code>\uff1a\u5b9a\u7fa9MDL\u7684\u6578\u64da\u7d50\u69cb\u548c\u63a5\u53e3\u3002<\/li>\n<li><code>sql\/handler.cc<\/code>\uff1a\u8655\u7406\u8207\u8868\u548c\u6578\u64da\u5eab\u76f8\u95dc\u7684\u64cd\u4f5c\u6642\u7684MDL\u9396\u5b9a\u3002<\/li>\n<\/ul>\n<p>\u4ee5\u4e0b\u662f\u4e00\u6bb5\u7c21\u55ae\u7684\u793a\u4f8b\u4ee3\u78bc\uff0c\u5c55\u793a\u5982\u4f55\u5728MySQL\u4e2d\u8acb\u6c42MDL\u9396\u5b9a\uff1a<\/p>\n<pre><code>\nMDL_request request;\nrequest.set_type(MDL_SHARED); \/\/ \u8a2d\u7f6e\u70ba\u5171\u4eab\u9396\nif (mdl_lock(&amp;request)) {\n    \/\/ \u7372\u5f97\u9396\u5b9a\uff0c\u57f7\u884c\u64cd\u4f5c\n} else {\n    \/\/ \u9396\u5b9a\u5931\u6557\uff0c\u8655\u7406\u932f\u8aa4\n}\n<\/code><\/pre>\n<h2 id=\"mdl%e5%ad%97%e5%85%b8%e9%8e%96%e7%9a%84%e4%bd%bf%e7%94%a8%e5%a0%b4%e6%99%af-NaloaYxEec\">MDL\u5b57\u5178\u9396\u7684\u4f7f\u7528\u5834\u666f<\/h2>\n<p>MDL\u5b57\u5178\u9396\u5728\u591a\u7528\u6236\u74b0\u5883\u4e2d\u5c24\u70ba\u91cd\u8981\uff0c\u7279\u5225\u662f\u5728\u4ee5\u4e0b\u5834\u666f\u4e2d\uff1a<\/p>\n<ul>\n<li>\u591a\u500b\u4e8b\u52d9\u540c\u6642\u8b80\u53d6\u548c\u5beb\u5165\u540c\u4e00\u8868\u6642\uff0cMDL\u53ef\u4ee5\u9632\u6b62\u6578\u64da\u4e0d\u4e00\u81f4\u3002<\/li>\n<li>\u5728\u9032\u884c\u7d50\u69cb\u8b8a\u66f4\uff08\u5982\u6dfb\u52a0\u5217\u6216\u4fee\u6539\u7d22\u5f15\uff09\u6642\uff0cMDL\u53ef\u4ee5\u78ba\u4fdd\u64cd\u4f5c\u7684\u5b89\u5168\u6027\u3002<\/li>\n<li>\u5728\u57f7\u884c\u9577\u6642\u9593\u904b\u884c\u7684\u67e5\u8a62\u6642\uff0cMDL\u53ef\u4ee5\u9632\u6b62\u5176\u4ed6\u4e8b\u52d9\u5c0d\u5143\u6578\u64da\u7684\u4fee\u6539\u3002<\/li>\n<\/ul>\n<h2 id=\"%e7%b8%bd%e7%b5%90-NaloaYxEec\">\u7e3d\u7d50<\/h2>\n<p>MDL\u5b57\u5178\u9396\u5728MySQL\u4e2d\u626e\u6f14\u8457\u81f3\u95dc\u91cd\u8981\u7684\u89d2\u8272\uff0c\u78ba\u4fdd\u4e86\u6578\u64da\u5eab\u64cd\u4f5c\u7684\u5b89\u5168\u6027\u548c\u4e00\u81f4\u6027\u3002\u901a\u904e\u6709\u6548\u5730\u7ba1\u7406\u5c0d\u5143\u6578\u64da\u7684\u8a2a\u554f\uff0cMDL\u80fd\u5920\u9632\u6b62\u6578\u64da\u885d\u7a81\u548c\u4e0d\u4e00\u81f4\u7684\u554f\u984c\u3002\u5c0d\u65bc\u5e0c\u671b\u6df1\u5165\u4e86\u89e3MySQL\u6e90\u78bc\u7684\u958b\u767c\u8005\u4f86\u8aaa\uff0c\u638c\u63e1MDL\u5b57\u5178\u9396\u7684\u5de5\u4f5c\u539f\u7406\u548c\u5be6\u73fe\u65b9\u5f0f\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002<\/p>\n<p>\u5982\u679c\u60a8\u6b63\u5728\u5c0b\u627e\u7a69\u5b9a\u7684 <a href=\"https:\/\/server.hk\">\u9999\u6e2fVPS<\/a> \u89e3\u6c7a\u65b9\u6848\uff0cServer.HK \u63d0\u4f9b\u591a\u7a2e\u9078\u64c7\u4ee5\u6eff\u8db3\u60a8\u7684\u9700\u6c42\u3002\u7121\u8ad6\u662f\u6578\u64da\u5eab\u7ba1\u7406\u9084\u662f\u61c9\u7528\u90e8\u7f72\uff0c\u6211\u5011\u7684 <a href=\"https:\/\/server.hk\">\u4f3a\u670d\u5668<\/a> \u90fd\u80fd\u70ba\u60a8\u63d0\u4f9b\u5f37\u5927\u7684\u652f\u6301\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6df1\u5165\u63a2\u8a0eMySQL\u6e90\u78bc\u4e2d\u7684MDL\u5b57\u5178\u9396\uff0c\u4e86\u89e3\u5176\u904b\u4f5c\u539f\u7406\u53ca\u5728\u6578\u64da\u5eab\u7ba1\u7406\u4e2d\u7684\u91cd\u8981\u6027\u3002<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-77556","post","type-post","status-publish","format-standard","hentry","category-database"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/77556","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=77556"}],"version-history":[{"count":1,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/77556\/revisions"}],"predecessor-version":[{"id":77557,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/77556\/revisions\/77557"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=77556"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=77556"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=77556"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}