sys.internal_tables (Transact-SQL)
Returns one row for each object that is an internal table. Internal tables are automatically generated by SQL Server to support various features. For example, when you create a primary XML index, SQL Server automatically creates an internal table to persist the shredded XML document data. Internal tables appear in the sys schema of every database and have unique, system-generated names that indicate their function, for example, xml_index_nodes_2021582240_32001 or queue_messages_1977058079
Internal tables do not contain user-accessible data, and their schema are fixed and unalterable. You cannot reference internal table names in Transact-SQL statements. For example, you cannot execute a statement such as SELECT * FROM <sys.internal_table_name>. However, you can query catalog views to see the metadata of internal tables.
Column name |
Data type |
Description |
|---|---|---|
<Columns inherited from sys.objects> |
|
For a list of columns that this view inherits, see sys.objects (Transact-SQL). |
internal_type |
tinyint |
Type of the internal table: 201 = queue_messages 202 = xml_index_nodes 203 = fulltext_catalog_freelist 204 = fulltext_catalog_map 205 = query_notification 206 = service_broker_map 207 = extended_indexes (such as a spatial index) 208 = filestream_tombstone 209 = change_tracking 210 = tracked_committed_transactions |
internal_type_desc |
nvarchar(60) |
Description of the type of internal table: QUEUE_MESSAGES XML_INDEX_NODES FULLTEXT_CATALOG_FREELIST FULLTEXT_CATALOG_MAP QUERY_NOTIFICATION SERVICE_BROKER_MAP EXTENDED_INDEXES FILESTREAM_TOMBSTONE CHANGE_TRACKING TRACKED_COMMITTED_TRANSACTIONS |
parent_id |
int |
ID of the parent, regardless of whether it is schema-scoped or not. Otherwise, 0 if there is no parent. queue_messages = object_id of queue xml_index_nodes = object_id of the xml index fulltext_catalog_freelist = fulltext_catalog_id of the full-text catalog fulltext_index_map = object_id of the full-text index query_notification, or service_broker_map = 0 extended_indexes = object_id of an extended index, such as a spatial index object_id of the table for which table tracking is enabled = change_tracking |
parent_minor_id |
int |
Minor ID of the parent. xml_index_nodes = index_id of the XML index extended_indexes = index_id of an extended index, such as a spatial index 0 = queue_messages, fulltext_catalog_freelist, fulltext_index_map, query_notification, service_broker_map, or change_tracking |
lob_data_space_id |
int |
Non-zero value is the ID of data space (filegroup or partition-scheme) that holds the large object (LOB) data for this table. |
filestream_data_space_id |
int |
Reserved for future use. |
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.
Remarks
Internal tables are placed on the same filegroup as the parent entity. You can use the catalog query shown in Example F below to return the number of pages internal tables consume for in-row, out-of-row, and large object (LOB) data.
You can use the sp_spaceused system procedure to return space usage data for internal tables. sp_spaceused reports internal table space in the following ways:
When a queue name is specified, the underlying internal table associated with the queue is referenced and its storage consumption is reported.
Pages that are used by the internal tables of XML indexes, spatial indexes, and full-text indexes are included in the index_size column. When a table or indexed view name is specified, the pages for the XML indexes, spatial indexes, and full-text indexes for that object are included in the columns reserved and index_size.
Examples
The following examples demonstrate how to query internal table metadata by using catalog views.
A. Show internal tables that inherit columns from the sys.objects catalog view
SELECT * FROM sys.objects WHERE type = 'IT';
B. Return all internal table metadata (including that which is inherited from sys.objects)
SELECT * FROM sys.internal_tables;
C. Return internal table columns and column data types
SELECT SCHEMA_NAME(itab.schema_id) AS schema_name
,itab.name AS internal_table_name
,typ.name AS column_data_type
,col.*
FROM sys.internal_tables AS itab
JOIN sys.columns AS col ON itab.object_id = col.object_id
JOIN sys.types AS typ ON typ.user_type_id = col.user_type_id
ORDER BY itab.name, col.column_id;
D. Return internal table indexes
SELECT SCHEMA_NAME(itab.schema_id) AS schema_name
, itab.name AS internal_table_name
, idx.*
FROM sys.internal_tables AS itab
JOIN sys.indexes AS idx ON itab.object_id = idx.object_id
ORDER BY itab.name, idx.index_id;
E. Return internal table statistics
SELECT SCHEMA_NAME(itab.schema_id) AS schema_name
,itab.name AS internal_table_name
, s.*
FROM sys.internal_tables AS itab
JOIN sys.stats AS s ON itab.object_id = s.object_id
ORDER BY itab.name, s.stats_id;
F. Return internal table partition and allocation unit information
SELECT SCHEMA_NAME(itab.schema_id) AS schema_name
,itab.name AS internal_table_name
,idx.name AS heap_or_index_name
,p.*
,au.*
FROM sys.internal_tables AS itab
JOIN sys.indexes AS idx
-- JOIN to the heap or the clustered index
ON itab.object_id = idx.object_id AND idx.index_id IN (0,1)
JOIN sys.partitions AS p
ON p.object_id = idx.object_id AND p.index_id = idx.index_id
JOIN sys.allocation_units AS au
-- IN_ROW_DATA (type 1) and ROW_OVERFLOW_DATA (type 3) => JOIN to partition's Hobt
-- else LOB_DATA (type 2) => JOIN to the partition ID itself.
ON au.container_id =
CASE au.type
WHEN 2 THEN p.partition_id
ELSE p.hobt_id
END
ORDER BY itab.name, idx.index_id;
G. Return internal table metadata for XML indexes
SELECT t.name AS parent_table
,t.object_id AS parent_table_id
,it.name AS internal_table_name
,it.object_id AS internal_table_id
,xi.name AS primary_XML_index_name
,xi.index_id as primary_XML_index_id
FROM sys.internal_tables AS it
JOIN sys.tables AS t
ON it.parent_id = t.object_id
JOIN sys.xml_indexes AS xi
ON it.parent_id = xi.object_id
AND it.parent_minor_id = xi.index_id
WHERE it.internal_type_desc = 'XML_INDEX_NODES';
GO
H. Return internal table metadata for Service Broker queues
SELECT q.name AS queue_name
,q.object_id AS queue_id
,it.name AS internal_table_name
,it.object_id AS internal_table_id
FROM sys.internal_tables AS it
JOIN sys.service_queues AS q ON it.parent_id = q.object_id
WHERE it.internal_type_desc = 'QUEUE_MESSAGES';
GO
I. Return internal table metadata for all Service Broker services
SELECT *
FROM tempdb.sys.internal_tables
WHERE internal_type_desc = 'SERVICE_BROKER_MAP';
GO