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title sys.external_tables (Transact-SQL)
description sys.external_tables (Transact-SQL)
author rwestMSFT
ms.author randolphwest
ms.reviewer hudequei, wiassaf, mikeray
ms.date 05/13/2025
ms.service sql
ms.subservice system-objects
ms.topic reference
ms.custom
ignite-2025
f1_keywords
external_tables
sys.external_tables
dev_langs
TSQL
monikerRange >=aps-pdw-2016 || =azuresqldb-current || =azure-sqldw-latest || >=sql-server-2016 || >=sql-server-linux-2017 || =azuresqldb-mi-current || =fabric || =fabric-sqldb

sys.external_tables (Transact-SQL)

[!INCLUDE sqlserver2016-asdb-asdbmi-asa-pdw-fabricdw-fabricsqldb]

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.

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