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sys.dm_db_partition_stats (Transact-SQL)

Returns page and row-count information for every partition in the current database.

Column name

Data type

Description

partition_id

bigint

ID of the partition. This is unique within a database. This is the same value as the partition_id in the sys.partitions catalog view

object_id

int

Object ID of the table or indexed view that the partition is part of.

index_id

int

ID of the heap or index the partition is part of.

0 = Heap

1 = Clustered index.

> 1 = Nonclustered index

partition_number

int

1-based partition number within the index or heap.

in_row_data_page_count

bigint

Number of pages in use for storing in-row data in this partition. If the partition is part of a heap, the value is the number of data pages in the heap. If the partition is part of an index, the value is the number of pages in the leaf level. (Nonleaf pages in the B-tree are not included in the count.) IAM (Index Allocation Map) pages are not included in either case. Always 0 for an xVelocity memory optimized columnstore index.

in_row_used_page_count

bigint

Total number of pages in use to store and manage the in-row data in this partition. This count includes nonleaf B-tree pages, IAM pages, and all pages included in the in_row_data_page_count column. Always 0 for a columnstore index.

in_row_reserved_page_count

bigint

Total number of pages reserved for storing and managing in-row data in this partition, regardless of whether the pages are in use or not. Always 0 for a columnstore index.

lob_used_page_count

bigint

Number of pages in use for storing and managing out-of-row text, ntext, image, varchar(max), nvarchar(max), varbinary(max), and xml columns within the partition. IAM pages are included.

Total number of LOBs used to store and manage columnstore index in the partition.

lob_reserved_page_count

bigint

Total number of pages reserved for storing and managing out-of-row text, ntext, image, varchar(max), nvarchar(max), varbinary(max), and xml columns within the partition, regardless of whether the pages are in use or not. IAM pages are included.

Total number of LOBs reserved for storing and managing a columnstore index in the partition.

row_overflow_used_page_count

bigint

Number of pages in use for storing and managing row-overflow varchar, nvarchar, varbinary, and sql_variant columns within the partition. IAM pages are included.

Always 0 for a columnstore index.

row_overflow_reserved_page_count

bigint

Total number of pages reserved for storing and managing row-overflow varchar, nvarchar, varbinary, and sql_variant columns within the partition, regardless of whether the pages are in use or not. IAM pages are included.

Always 0 for a columnstore index.

used_page_count

bigint

Total number of pages used for the partition. Computed as in_row_used_page_count + lob_used_page_count + row_overflow_used_page_count.

reserved_page_count

bigint

Total number of pages reserved for the partition. Computed as in_row_reserved_page_count + lob_reserved_page_count + row_overflow_reserved_page_count.

row_count

bigint

The approximate number of rows in the partition.

sys.dm_db_partition_stats displays information about the space used to store and manage in-row data LOB data, and row-overflow data for all partitions in a database. One row is displayed per partition.

The counts on which the output is based are cached in memory or stored on disk in various system tables.

In-row data, LOB data, and row-overflow data represent the three allocation units that make up a partition. The sys.allocation_units catalog view can be queried for metadata about each allocation unit in the database.

If a heap or index is not partitioned, it is made up of one partition (with partition number = 1); therefore, only one row is returned for that heap or index. The sys.partitions catalog view can be queried for metadata about each partition of all the tables and indexes in a database.

The total count for an individual table or an index can be obtained by adding the counts for all relevant partitions.

Requires VIEW DATABASE STATE permission to query the sys.dm_db_partition_stats dynamic management view. For more information about permissions on dynamic management views, see Dynamic Management Views and Functions (Transact-SQL).

A. Returning all counts for all partitions of all indexes and heaps in a database

The following example shows all counts for all partitions of all indexes and heaps in the AdventureWorks2012 database.

USE AdventureWorks2012;
GO
SELECT * FROM sys.dm_db_partition_stats;
GO

B. Returning all counts for all partitions of a table and its indexes

The following example shows all counts for all partitions of the HumanResources.Employee table and its indexes.

USE AdventureWorks2012;
GO
SELECT * FROM sys.dm_db_partition_stats 
WHERE object_id = OBJECT_ID('HumanResources.Employee');
GO

C. Returning total used pages and total number of rows for a heap or clustered index

The following example returns total used pages and total number of rows for the heap or clustered index of the HumanResources.Employee table. Because the Employee table is not partitioned by default, note the sum includes only one partition.

USE AdventureWorks2012;
GO
SELECT SUM(used_page_count) AS total_number_of_used_pages, 
    SUM (row_count) AS total_number_of_rows 
FROM sys.dm_db_partition_stats
WHERE object_id=OBJECT_ID('HumanResources.Employee')    AND (index_id=0 or index_id=1);
GO
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