Building external tables

External tables are similar to regular tables except that the data is stored in external storage locations such as Azure Data Lake, Azure Blob storage, and HDFS. With external tables, you don't need to copy data into internal tables for processing. They can directly read the data from external sources, which saves on the data transfer cost. In Synapse, both dedicated SQL and serverless SQL support external tables. We have to define the following three constructs to access data via external tables:

• EXTERNAL DATA SOURCE

Here is an example of how we can create an external data source named users_iacstoreacct:

CREATE EXTERNAL DATA SOURCE [Dp203DataSource] 
	WITH ( LOCATION  = 'abfss://path/to/data')

• EXTERNAL FILE FORMAT

Here is an example of how to create an external file format named SynapseParquetFormat:

CREATE EXTERNAL FILE FORMAT [Dp203ParquetFormat] 
	WITH ( FORMAT_TYPE = PARQUET )

• EXTERNAL...