sys.external_tables (Transact-SQL)
Applies to: 
SQL Server 2016 (13.x) and later
Azure SQL Database
Azure SQL Managed Instance
Azure Synapse Analytics
Analytics Platform System (PDW)
Contains a row for each external table in the current database.
| Column Name | Data Type | Description | Range |
|---|---|---|---|
| <inherited columns> | For a list of columns that this view inherits, see sys.objects (Transact-SQL). | ||
| max_column_id_used | int | Maximum column ID ever used for this table. | |
| uses_ansi_nulls | bit | Table was created with the SET ANSI_NULLS database option ON. | |
| data_source_id | int | Object ID for the external data source. | |
| file_format_id | int | For external tables over a HADOOP external data source, this is the Object ID for the external file format. | |
| location | nvarchar(4000) | For external tables over a HADOOP external data source, this is the path of the external data in HDFS. | |
| reject_type | tinyint | For external tables over a HADOOP external data source, this is the way rejected rows are counted when querying external data. | VALUE - the number of rejected rows. PERCENTAGE - the percentage of rejected rows. |
| reject_value | float | For external tables over a HADOOP external data source: For reject_type = value, this is the number of row rejections to allow before failing the query. For reject_type = percentage, this is the percentage of row rejections to allow before failing the query. |
|
| reject_sample_value | int | For reject_type = percentage, this is the number of rows to load, either successfully or unsuccessfully, before calculating the percentage of rejected rows. | NULL if reject_type = VALUE. |
| distribution_type | int | For external tables over a SHARD_MAP_MANAGER external data source, this is the data distribution of the rows across the underlying base tables. | 0 - Sharded 1 - Replicated 2 - Round robin |
| distribution_desc | nvarchar(120) | For external tables over a SHARD_MAP_MANAGER external data source, this is the distribution type displayed as a string. | |
| sharding_column_id | int | For external tables over a SHARD_MAP_MANAGER external data source and a sharded distribution, this is the column ID of the column that contains the sharding key values. | |
| remote_schema_name | sysname | For external tables over a SHARD_MAP_MANAGER external data source, this is the schema where the base table is located on the remote databases (if different from the schema where the external table is defined). | |
| remote_object_name | sysname | For external tables over a SHARD_MAP_MANAGER external data source, this is the name of the base table on the remote databases (if different from the name of the external table). |
Permissions
The visibility of the metadata in catalog views is limited to securables that a user either owns or on which the user has been granted some permission. For more information, see Metadata Visibility Configuration.
See Also
sys.external_file_formats (Transact-SQL)
sys.external_data_sources (Transact-SQL)
CREATE EXTERNAL TABLE (Transact-SQL)