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2024年4月16日发(作者:c语言求最大公约数和最小公倍数函数调用)
spark作业运行流程
英文回答:
The workflow of a Spark job involves several steps,
including data input, transformation, and output. Let me
explain the process in detail.
1. Data Input:
The first step in running a Spark job is to provide the
input data. This can be done by reading data from various
sources such as Hadoop Distributed File System (HDFS),
Amazon S3, or local file systems. Spark supports reading
data in various formats like CSV, JSON, Parquet, etc. For
example, you can read a CSV file using the following code
in Scala:
scala.
val data = ("csv").option("header",
"true").load("")。
2. Transformation:
Once the data is loaded into Spark, you can perform
various transformations on it. Transformations are
operations that produce a new dataset from an existing one.
Spark provides a rich set of transformation functions like
map, filter, reduce, join, etc. These transformations are
lazily evaluated, meaning they are not executed immediately
but rather when an action is called. For instance, you can
transform the data by filtering out certain records using
the filter transformation:
scala.
val filteredData = ("age > 18")。
3. Action:
Actions are operations that trigger the execution of
all the transformations and produce a result or write data
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