{"id":16124,"date":"2025-03-12T14:43:16","date_gmt":"2025-03-12T06:43:16","guid":{"rendered":"https:\/\/nj.transwarp.cn:8180\/?p=16124"},"modified":"2025-06-17T16:38:32","modified_gmt":"2025-06-17T08:38:32","slug":"sql%e5%b8%b8%e8%a7%81%e6%8a%a5%e9%94%99%e4%b9%8b-data-skew-for-single-key-found","status":"publish","type":"post","link":"https:\/\/kbwp.transwarp.cn\/?p=16124","title":{"rendered":"sql\u5e38\u89c1\u62a5\u9519\u4e4b Data skew for single key found"},"content":{"rendered":"

\u95ee\u9898\u8bf4\u660e<\/h3>\n
\n

\u62a5\u9519\u4fe1\u606f\uff1aData skew for single key found. key content : […] has too many values. Values exceed safety size : 536870912(536870994)<\/p>\n

\u987e\u540d\u601d\u4e49\uff0c\u56e0\u4e3a\u67d0\u4e9b\u503c\u8fc7\u591a\u5bfc\u81f4\u6570\u636e\u503e\u659c\uff0c\u672c\u6587\u7ed9\u51fa\u76f8\u5173\u89e3\u91ca\u8bf4\u660e\u53ca\u89e3\u51b3\u65b9\u6848\u3002<\/p>\n

\u6545\u969c\u6392\u67e5<\/h3>\n
\n

\u6d89\u53ca\u5230\u4e00\u4e2a\u53c2\u6570\uff0cngmr.safety.size.single.entry<\/code>\uff0c\u9ed8\u8ba4\u503c 536870912\uff0c\u5355\u4f4dbyte\u3002 \u8868\u793a\u5355\u4e2atask\u5185\u76f8\u540ckey\u5bf9\u5e94\u7684value\u7684\u6570\u636e\u91cf\u8fbe\u5230\u4e86512M \u7684\u4e0a\u9650\uff0c\u5224\u5b9a\u4e3a\u6570\u636e\u503e\u659c\u3002<\/p>\n

\u4ee5\u4e0b\u56fe\u4e3a\u4f8b\uff0cliang\u4e24\u5f20\u8868left join<\/code> \u65f6\u62a5\u9519 Data skew for single key found. key content : [1,49,50,54,56,54,54,55,57,0] has too many values. Values exceed safety size : 536870912(536870994)<\/code><\/p>\n

\n <\/div>\n

\u4eceDBAService Query\u9875\u9762DAG\u4e5f\u80fd\u770b\u5230\u65f6\u4e24\u4e2a\u8868\u7684common join\u9636\u6bb5\u3002<\/p>\n

\n <\/div>\n

\u67e5\u627e\u96c6\u4e2d\u7684joinkey\u7684\u65b9\u6cd5\uff1a<\/strong><\/p>\n

sql\u65b9\u5f0f\uff0c\u53ef\u4ee5\u53c2\u8003 sql\u5e38\u89c1\u62a5\u9519\u4e4b bucket size is too large (>2G) after compress<\/a> \u4e2d\u63d0\u5230\u7684\u4e09\u79cd\u65b9\u6cd5\u3002<\/p>\n

\u8fd9\u91cc\u6211\u4eec\u5bf9\u5de6\u53f3\u4e24\u8868 \u5206\u522b\u805a\u5408\u67e5\u8be2 \u7edf\u8ba1\u51fa\u4e24\u8fb9joinkey\u7684\u6570\u91cf\uff1a<\/p>\n

--\u5de6\u8868\uff1a\nSELECT A1.ACCOUNT_ID,COUNT(*) \nFROM ODSCRM.PLATFORM_ENS_D_ACCOUNT_MERGE A1 \nWHERE A1.IS_BALANCE='Y' \nGROUP BY A1.ACCOUNT_ID \nORDER BY 2 DESC \nLIMIT 20;\n\n--\u53f3\u8868\uff1a\nSELECT A3.ACCOUNT_ID,COUNT(*) \nFROM ODSCRM.PLATFORM_ENS_F_ENTRY_MERGE A3 \nGROUP BY A3.ACCOUNT_ID \nORDER BY 2 DESC \nLIMIT 20;<\/code><\/pre>\n
\n  <\/div>\n
\n  <\/div>\n
\u53ef\u4ee5\u770b\u5230\u53f3\u8868A3\uff0c\u5728 joinkey A3.ACCOUNT_ID='12686679'<\/code>\u65f6\uff0c\u503e\u659c\u8f83\u4e3a\u4e25\u91cd\uff0c\u670929082901\u6761\u91cd\u590d\u6570\u636e\u3002<\/p>\n
\u8fd9\u91cc\u518d\u63d0\u4f9b\u4e00\u79cd\u59ff\u52bf\uff0c\u6839\u636e\u62a5\u9519byte\u6570\u7ec4\u76f4\u63a5\u89e3\u6790\u51fa\u503e\u659ckey\u7684\u503c\u3002<\/strong><\/p>\n
\u501f\u52a9java\u4ee3\u7801\uff0c\u5b9e\u73b0 \u5c06\u5b57\u8282\u6570\u7ec4\uff08byte[]\uff09\u8f6c\u6362\u4e3a UTF-8 \u7f16\u7801\u7684\u5b57\u7b26\u4e32<\/p>\n
import java.nio.charset.StandardCharsets;\npublic class byte2stringREAL {\n    public static void main(String[] args) {\n        byte[] bytes = new byte[]{1,49,50,54,56,54,54,55,57,0};\n        System.out.println(\"Text : \" + bytes);\n        String s = new String(bytes, StandardCharsets.UTF_8);\n        System.out.println(\"Output : \" + s);\n    }\n}<\/code><\/pre>\n
\n  <\/div>\n
\u4e5f\u80fd\u591f\u5f97\u5230 12686679 \u8fd9\u4e2a\u503c\u3002<\/p>\n
\u89e3\u51b3\u65b9\u6848<\/h3>\n
\n
\u9996\u5148\u8ba9\u5ba2\u6237\u5224\u65adsql\u7684\u4e1a\u52a1\u903b\u8f91\u662f\u5426\u5408\u7406\uff08\u6bd4\u5982\u7b1b\u5361\u5c14\u79ef\uff09\uff0c\u503e\u659c\u7684joinkey\u6570\u636e\u662f\u5426\u5f02\u5e38\uff08\u6bd4\u5982\u6ca1\u6709\u505a\u6570\u636e\u6e05\u6d17\uff09… <\/p>\n
\u5982\u679c\u90fd\u786e\u8ba4\u6ca1\u6709\u95ee\u9898\u7684\u8bdd\uff0c\u53ef\u4ee5\u5c1d\u8bd5\u4e0b\u9762\u7684\u89e3\u51b3\u65b9\u6848\uff1a<\/p>\n
\u65b9\u6848\u4e00\uff1aset ngmr.safety.size.single.entry=-1\uff0c\u653e\u5f00\u9650\u5236<\/h4>\n
\u4ec5\u9650session\u7ea7\u4f7f\u7528 \u4e34\u65f6workaround\uff0c\u4e0d\u53ef\u4ee5\u5168\u5c40\u914d\u7f6e\u3002<\/p>\n
\u65b9\u6848\u4e8c\uff1amapjoin \uff08\u53c2\u8003\u5185\u90e8\u6587\u6863 Inceptor Mapjoin \u4f7f\u7528\u8bf4\u660e<\/a>\uff09:<\/h4>\n
mapjoin\u7684hive.mapjoin.smalltable.filesize<\/code>\u5728\u9ad8\u7248\u672c\u5df2\u7ecf\u5168\u5c40\u964d\u4f4e\u52305000000\uff0c\u5982\u679c\u5728\u8fd9\u4e2a\u914d\u7f6e\u4e0b\u4ecd\u7136\u65e0\u6cd5\u8d70mapjoin\u7684\u8bdd\uff0c\u53ef\u4ee5\u914c\u60c5\u5bf9\u5c0f\u8868\u8d70\u5f3a\u5236mapjoin hint (\u614e\u7528)\uff0c\u6bd4\u5982\uff1a<\/p>\n
SELECT \/*+MAPJOIN(table_B)*\/\n    ...\nFROM table_A [left] JOIN table_B\nON ...;\n--\u5176\u4e2d table_B \u4e3a\u5c0f\u8868<\/code><\/pre>\n
\u65b9\u6848\u4e09\uff1askewjoin \uff08\u53c2\u8003\u5185\u90e8\u6587\u6863 ArgoDB SKEWJOIN \u4f7f\u7528\u8bf4\u660e<\/a>\uff09:<\/h4>\n
SET quark.join.null.optimize=TRUE;\nSET quark.skewjoin.hint.enable=TRUE;\nSET ngmr.windrunner.session.orc=TRUE;\nSET ngmr.windrunner.nonquery.enabled=TRUE;\n\nSELECT \/*+ skewjoin(b(serialno)[(0),(4421),(4412)])*\/\n    ...\nFROM table_A a [left] JOIN table_B b\nON a.srno=b.serialno\n...<\/code><\/pre>\n
\n
\/+SKEWJOIN(table_alias (column_name) [(skew_value)],table_alias (column_name) [(skew_value)]…)<\/em>\/
\n\u6574\u4f53 hint \u8bed\u6cd5\u5982\u4e0a\uff0c\u5927\u4f53\u4e0a\u5206\u4e3a\u201ctable_alias \u8868\u522b\u540d\u201d\u3001\u201ccolumn_name \u8fde\u63a5\u5217\u540d\u201d\u3001\u201cskew_value \u503e\u659c\u503c\u201d\u4e09\u90e8\u5206<\/p>\n<\/blockquote>\n","protected":false},"excerpt":{"rendered":"
\u95ee\u9898\u8bf4\u660e \u62a5\u9519\u4fe1\u606f\uff1aData skew for single key found. key content : ..<\/p>\n
<\/div>\n
Read more<\/a><\/p>\n","protected":false},"author":12,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-16124","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"acf":[],"_links":{"self":[{"href":"https:\/\/kbwp.transwarp.cn\/index.php?rest_route=\/wp\/v2\/posts\/16124","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kbwp.transwarp.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kbwp.transwarp.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kbwp.transwarp.cn\/index.php?rest_route=\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/kbwp.transwarp.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=16124"}],"version-history":[{"count":3,"href":"https:\/\/kbwp.transwarp.cn\/index.php?rest_route=\/wp\/v2\/posts\/16124\/revisions"}],"predecessor-version":[{"id":16748,"href":"https:\/\/kbwp.transwarp.cn\/index.php?rest_route=\/wp\/v2\/posts\/16124\/revisions\/16748"}],"wp:attachment":[{"href":"https:\/\/kbwp.transwarp.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=16124"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kbwp.transwarp.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=16124"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kbwp.transwarp.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=16124"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}