The OUTPUT writes data from a rowset to a file.Extractors.Tsv is a built-in U-SQL extractor for tab-separated-value files. The EXTRACT keyword reads data from a file and defines the schema on read.U-SQL follows the T-SQL variable naming pattern ( for example) in the script. Rowset variables: Each query expression that produces a rowset can be assigned to a variable.It means that the Duration field could be null. Notice the question mark next to the data type in the Duration field. It reads from the source file called SearchLog.tsv, schematizes it, and writes the rowset back into a file called SearchLog-first-u-sql.csv. This script doesn't have any transformation steps. OUTPUT "/output/SearchLog-first-u-sql.csv" Now that we have some data, let's read it from the file we created. We'll discuss the key concepts that make this script go in the next section. The following U-SQL script is simple and lets us create a sample data file that we can reference in our other U-SQL scripts. To understand the U-SQL design philosophy, see the Visual Studio blog post Introducing U-SQL – A Language that makes Big Data Processing Easy.For detailed information about the U-SQL language syntax, see the U-SQL Language Reference.This document is recommended reading for all developers wanting to learn U-SQL. The U-SQL Tutorial provides a guided walkthrough of most of the U-SQL language. Additionally, U-SQL includes extensibility that gives you fine-grained control over how to execute at scale. With U-SQL, you can process unstructured data by applying schema on read and inserting custom logic and UDFs. Through the scalable, distributed-query capability of U-SQL, you can efficiently analyze data across relational stores such as Azure SQL Database. U-SQL is a language that combines declarative SQL with imperative C# to let you process data at any scale. If you're already using Azure Data Lake Analytics, you can create a migration plan to Azure Synapse Analytics for your organization. Azure Data Lake Analytics will be retired on 29 February 2024.
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