On the SQL tab, We could see that tables with 38, 34, 58 and 289 million records were being read. It seemed to be stuck on theSortMergeJoinphase withnumber of output rows as 100,000,000,000 (rounded).That is 100 billion records which are way more than the total combined data from ...
mapreduce的reduce函数一次可以拿到所有的该key对应的value列表,所以shuffle需要排序,等待所有的数据。而spark的map每写入一点数据ResultTask可以拉取进行聚合(groupbykey除外)。 Spark允许用户将数据加载至集群存储器,并多次对其进行查询,非常适合用于机器学习算法。 支持一组丰富的高级工具,包括使用 SQL 处理结构化数据处理...
[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-Ijb4itkp-1619166361038)(C:\Users\Yuao\Desktop\学习笔记\pic\scala类强转.png)] 7.进入DataSet.ofRows(sparkSession,logicalPlan) def ofRows(sparkSession: SparkSession, logicalPlan: LogicalPlan): DataFrame = { val qe = sparkS...
Spark – How to remove duplicate rows How to Pivot and Unpivot a Spark DataFrame Spark SQL Data Types with Examples Spark SQL StructType & StructField with examples Spark schema – explained with examples Spark Groupby Example with DataFrame Spark – How to Sort DataFrame column explained Spark SQ...
// If we didn't find any rows after the previous iteration, quadruple and retry. // Otherwise, interpolate the number of partitions we need to try, but overestimate // it by 50%. We also cap the estimation in the end. if (buf.size == 0) { ...
背景 该sql运行在spark版本 3.1.2下的thrift server下 现象 在运行包含多个union 的spark sql的时候报错(该sql包含了50多个uinon,且每个union字查询中会包含join操作),其中union中子查询sql类似如下: SELECTa1.order_no ,a1.need_column ,a1.join_id ...
Drop missing values Remove rows with missing values Drop duplicate rows Drop all rows that have duplicate values in one or more columns Fill missing values Replace cells with missing values with a new value Find and replace Replace cells with an exact matching pattern Group by column and aggregat...
merge- replace rows with new rows by matching on the primary key. (Use this option only if you need to fully rewrite existing rows with new ones. To specify some rule for the update, use theonDuplicateKeySQLoption instead.) All these options are case-insensitive. ...
Drop missing values Remove rows with missing values Drop duplicate rows Drop all rows that have duplicate values in one or more columns Fill missing values Replace cells with missing values with a new value Find and replace Replace cells with an exact matching pattern Group by column and aggregat...
Let's use thecollect_list()method to eliminate all the rows with duplicateletter1andletter2rows in the DataFrame and collect all thenumber1entries as a list. df .groupBy("letter1", "letter2") .agg(collect_list("number1") as "number1s") ...