orc table creation from spark sql with snappy compression

CREATE EXTERNAL FILE FORMAT to describe format of CSV or Parquet files.

CREATE EXTERNAL DATA SOURCE to reference an external Azure storage and specify the credential that should be used to access the storage.

You can create external tables in Synapse SQL pools via the following steps: If performance of Hadoop external tables in the dedicated pools do not satisfy your performance goals, consider loading external data into the Datawarehouse tables using the COPY statement.įor a loading tutorial, see Use PolyBase to load data from Azure Blob Storage. When used in conjunction with the CREATE TABLE AS SELECT statement, selecting from an external table imports data into a table within the dedicated SQL pool. You cannot use the dedicated SQL pools to export data using native tables. The columns in the external table definition are mapped to the columns in the underlying Parquet files by position.ĬETAS with the native tables as a target works only in the serverless SQL pool. The columns in the external table definition are mapped to the columns in the underlying Parquet files by column name matching. Ordinal - the columns in the external table definition are mapped to the columns in the underlying Parquet files by position. Shared Access Signature(SAS), Azure Active Directory passthrough, Managed identity, Custom application Azure AD identity.

Storage Access Key(SAK), Azure Active Directory passthrough, Managed identity, custom application Azure Active Directory identity In Dedicated pool the folders are always scanned recursively.

In serverless SQL pools must be specified /** at the end of the location path.

In the serverless SQL pool, you can also use recursive wildcards /logs/** to reference Parquet or CSV files in any sub-folder beneath the referenced folder. Custom folder paths are not available in Delta Lake. Yes, using wildcards like /year=*/month=*/day=* for Parquet or CSV formats. For more information on collations, refer to Collation types supported for Synapse SQL. For the string pushdown, you need to use Latin1_General_100_BIN2_UTF8 collation on the VARCHAR columns to enable pushdown. Use Delta partitioned views if you need to query partitioned Delta Lake data. Don't create external tables on Delta Lake folders because they aren't supported. You might create external tables on Parquet partitioned folders, but the partitioning columns are inaccessible and ignored, while the partition elimination won't be applied. Partition elimination is available only in the partitioned tables created on Parquet or CSV formats that are synchronized from Apache Spark pools. Serverless SQL pool: Delimited/CSV, Parquet, and Delta Lake Dedicated SQL pool: Parquet (preview) Only Parquet tables are available in public preview.ĭelimited/CSV, Parquet, ORC, Hive RC, and RC The key differences between Hadoop and native external tables: External table type Writing/exporting data using CETAS and the native external tables is available only in the serverless SQL pool, but not in the dedicated SQL pools. Native external tables are available in serverless SQL pools, and they are in public preview in dedicated SQL pools. Native external tables that you can use to read and export data in various data formats such as CSV and Parquet.Hadoop external tables are available in dedicated SQL pools, but they aren't available in serverless SQL pools. Hadoop external tables that you can use to read and export data in various data formats such as CSV, Parquet, and ORC.With Synapse SQL, you can use external tables to read external data using dedicated SQL pool or serverless SQL pool.ĭepending on the type of the external data source, you can use two types of external tables: You can use external tables to read data from files or write data to files in Azure Storage. An external table points to data located in Hadoop, Azure Storage blob, or Azure Data Lake Storage.

Orc table creation from spark sql with snappy compression