“`” \u89e3\u7b54\uff1a<\/p>\n
\u6570\u636e\u503e\u659c\uff1amap \/reduce\u7a0b\u5e8f\u6267\u884c\u65f6\uff0creduce\u8282\u70b9\u5927\u90e8\u5206\u6267\u884c\u5b8c\u6bd5\uff0c\u4f46\u662f\u6709\u4e00\u4e2a\u6216\u8005\u51e0\u4e2areduce\u8282\u70b9\u8fd0\u884c\u5f88\u6162\uff0c\u5bfc\u81f4\u6574\u4e2a\u7a0b\u5e8f\u7684\u5904\u7406\u65f6\u95f4\u5f88\u957f\uff0c\u8fd9\u662f\u56e0\u4e3a\u67d0\u4e00\u4e2akey\u7684\u6761\u6570\u6bd4\u5176\u4ed6key\u591a\u5f88\u591a\uff08\u6709\u65f6\u662f\u767e\u500d\u6216\u8005\u5343\u500d\u4e4b\u591a\uff09\uff0c\u8fd9\u6761key\u6240\u5728\u7684reduce\u8282\u70b9\u6240\u5904\u7406\u7684\u6570\u636e\u91cf\u6bd4\u5176\u4ed6\u8282\u70b9\u5c31\u5927\u5f88\u591a\uff0c\u4ece\u800c\u5bfc\u81f4\u67d0\u51e0\u4e2a\u8282\u70b9\u8fdf\u8fdf\u8fd0\u884c\u4e0d\u5b8c\uff0c\u6b64\u79f0\u4e4b\u4e3a\u6570\u636e\u503e\u659c\u3002<\/p>\n
\u7528hadoop\u7a0b\u5e8f\u8fdb\u884c\u6570\u636e\u5173\u8054\u65f6\uff0c\u5e38\u78b0\u5230\u6570\u636e\u503e\u659c\u7684\u60c5\u51b5\uff0c\u8fd9\u91cc\u63d0\u4f9b\u4e00\u79cd\u89e3\u51b3\u65b9\u6cd5\u3002<\/p>\n
\u81ea\u5df1\u5b9e\u73b0partition\u7c7b\uff0c\u7528key\u548cvalue\u76f8\u52a0\u53d6hash\u503c\uff1a<\/p>\n
\u65b9\u5f0f1\uff1a<\/p>\n
\u6e90\u4ee3\u7801\uff1a<\/p>\n
<pre><code>public int getPartition(K key, V value,int numReduceTasks) {
\n return (key.hashCode() & Integer.MAX_VALUE) % numReduceTasks;
\n }
\n<\/code><\/pre><\/p>\n
\u4fee\u6539\u540e<\/p>\n
<pre><code>public int getPartition(K key, V value,int numReduceTasks) {
\n return ((\uff08key).hashCode()+value.hashCode()\uff09 & Integer.MAX_VALUE) % numReduceTasks;
\n}
\n<\/code><\/pre><\/p>\n
\u65b9\u5f0f2\uff1a<\/p>\n
<pre><code>public class HashPartitioner<K, V> extends Partitioner<K, V> {<\/p>\n
private int aa= 0;<\/p>\n
\/** Use {@link Object#hashCode()} to partition. *\/<\/p>\n
public int getPartition(K key, V value,
\n int numReduceTasks) {<\/p>\n
return (key.hashCode()+(aa++) & Integer.MAX_VALUE) % numReduceTasks;
\n }
\n<\/code><\/pre><\/p>\n
<pre><code> "“`
\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
“`” \u89e3\u7b54\uff1a \u6570\u636e\u503e\u659c\uff1amap \/reduce\u7a0b\u5e8f\u6267\u884c\u65f6\uff0creduce\u8282\u70b9\u5927\u90e8\u5206\u6267\u884c […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-47653","post","type-post","status-publish","format-standard","hentry","category-c"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47653","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=47653"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47653\/revisions"}],"predecessor-version":[{"id":47654,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/47653\/revisions\/47654"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=47653"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=47653"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=47653"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}