SparkSQL - 直接读取镶木地板文件 [英] SparkSQL - Read parquet file directly

问题描述

我正在从 Impala 迁移到 SparkSQL，使用以下代码读取表:

I am migrating from Impala to SparkSQL, using the following code to read a table:

my_data = sqlContext.read.parquet('hdfs://my_hdfs_path/my_db.db/my_table')

我如何调用上面的 SparkSQL，以便它可以返回如下内容:

How do I invoke SparkSQL above, so it can return something like:

'select col_A, col_B from my_table'

推荐答案

从 parquet 文件创建 Dataframe 后，您必须将其注册为临时表以在其上运行 sql 查询.>

After creating a Dataframe from parquet file, you have to register it as a temp table to run sql queries on it.

val sqlContext = new org.apache.spark.sql.SQLContext(sc)

val df = sqlContext.read.parquet("src/main/resources/peopleTwo.parquet")

df.printSchema

// after registering as a table you will be able to run sql queries
df.registerTempTable("people")

sqlContext.sql("select * from people").collect.foreach(println)

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