将导航和图片路径转换为相对路径
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@@ -61,7 +61,7 @@ LOAD DATA LOCAL INPATH "/usr/file/emp30.txt" OVERWRITE INTO TABLE emp_partition
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这时候当你的查询语句的 `where` 包含 `deptno=20`,则就去对应的分区目录下进行查找,而不用扫描全表。
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<div align="center"> <img src="https://github.com/heibaiying/BigData-Notes/blob/master/pictures/hive-hadoop-partitation.png"/> </div>
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<div align="center"> <img src="../pictures/hive-hadoop-partitation.png"/> </div>
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@@ -79,7 +79,7 @@ LOAD DATA LOCAL INPATH "/usr/file/emp30.txt" OVERWRITE INTO TABLE emp_partition
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当调用 HashMap 的 put() 方法存储数据时,程序会先对 key 值调用 hashCode() 方法计算出 hashcode,然后对数组长度取模计算出 index,最后将数据存储在数组 index 位置的链表上,链表达到一定阈值后会转换为红黑树 (JDK1.8+)。下图为 HashMap 的数据结构图:
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<div align="center"> <img width="600px" src="https://github.com/heibaiying/BigData-Notes/blob/master/pictures/HashMap-HashTable.png"/> </div>
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<div align="center"> <img width="600px" src="../pictures/HashMap-HashTable.png"/> </div>
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> 图片引用自:[HashMap vs. Hashtable](http://www.itcuties.com/java/hashmap-hashtable/)
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@@ -123,13 +123,13 @@ INSERT INTO TABLE emp_bucket SELECT * FROM emp; --这里的 emp 表就是一
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可以从执行日志看到 CTAS 触发 MapReduce 操作,且 Reducer 数量和建表时候指定 bucket 数量一致:
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<div align="center"> <img src="https://github.com/heibaiying/BigData-Notes/blob/master/pictures/hive-hadoop-mapreducer.png"/> </div>
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<div align="center"> <img src="../pictures/hive-hadoop-mapreducer.png"/> </div>
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### 1.5 查看分桶文件
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bucket(桶) 本质上就是表目录下的具体文件:
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<div align="center"> <img src="https://github.com/heibaiying/BigData-Notes/blob/master/pictures/hive-hadoop-bucket.png"/> </div>
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<div align="center"> <img src="../pictures/hive-hadoop-bucket.png"/> </div>
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