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Maximum Capacity Specifications for SQL Server

The following tables specify the maximum sizes and numbers of various objects defined in SQL Server components.

The following table specifies the maximum sizes and numbers of various objects defined in SQL Server databases or referenced in Transact-SQL statements.

SQL Server Database Engine object

Maximum sizes/numbers SQL Server (32-bit)

Maximum sizes/numbers SQL Server (64-bit)

Batch size1

65,536 * Network Packet Size

65,536 * Network Packet Size

Bytes per short string column

8,000

8,000

Bytes per GROUP BY, ORDER BY

8,060

8,060

Bytes per index key2

900

900

Bytes per foreign key

900

900

Bytes per primary key

900

900

Bytes per row8

8,060

8,060

Bytes in source text of a stored procedure

Lesser of batch size or 250 MB

Lesser of batch size or 250 MB

Bytes per varchar(max), varbinary(max), xml, text, or image column

2^31-1

2^31-1

Characters per ntext or nvarchar(max) column

2^30-1

2^30-1

Clustered indexes per table

1

1

Columns in GROUP BY, ORDER BY

Limited only by number of bytes

Limited only by number of bytes

Columns or expressions in a GROUP BY WITH CUBE or WITH ROLLUP statement

10

10

Columns per index key7

16

16

Columns per foreign key

16

16

Columns per primary key

16

16

Columns per nonwide table

1,024

1,024

Columns per wide table

30,000

30,000

Columns per SELECT statement

4,096

4,096

Columns per INSERT statement

4096

4096

Connections per client

Maximum value of configured connections

Maximum value of configured connections

Database size

524,272 terabytes

524,272 terabytes

Databases per instance of SQL Server

32,767

32,767

Filegroups per database

32,767

32,767

Files per database

32,767

32,767

File size (data)

16 terabytes

16 terabytes

File size (log)

2 terabytes

2 terabytes

Foreign key table references per table4

253

253

Identifier length (in characters)

128

128

Instances per computer

50 instances on a stand-alone server for all SQL Server editions.

SQL Server supports 25 instances on a failover cluster.

50 instances on a stand-alone server for all SQL Server editions.

SQL Server supports 25 instances on a failover cluster.

Length of a string containing SQL statements (batch size)1

65,536 * Network packet size

65,536 * Network packet size

Locks per connection

Maximum locks per server

Maximum locks per server

Locks per instance of SQL Server5

Up to 2,147,483,647

Limited only by memory

Nested stored procedure levels6

32

32

Nested subqueries

32

32

Nested trigger levels

32

32

Nonclustered indexes per table

999

999

Number of distinct expressions in the GROUP BY clause when any of the following are present: CUBE, ROLLUP, GROUPING SETS, WITH CUBE, WITH ROLLUP

32

32

Number of grouping sets generated by operators in the GROUP BY clause

4,096

4,096

Parameters per stored procedure

2,100

2,100

Parameters per user-defined function

2,100

2,100

REFERENCES per table

253

253

Rows per table

Limited by available storage

Limited by available storage

Tables per database3

Limited by number of objects in a database

Limited by number of objects in a database

Partitions per partitioned table or index

1,000

1,000

Statistics on non-indexed columns

30,000

30,000

Tables per SELECT statement

Limited only by available resources

Limited only by available resources

Triggers per table3

Limited by number of objects in a database

Limited by number of objects in a database

Columns per UPDATE statement (Wide Tables)

4096

4096

User connections

32,767

32,767

XML indexes

249

249

1Network Packet Size is the size of the tabular data stream (TDS) packets used to communicate between applications and the relational Database Engine. The default packet size is 4 KB, and is controlled by the network packet size configuration option.

2The maximum number of bytes in any index key cannot exceed 900 in SQL Server. You can define a key using variable-length columns whose maximum sizes add up to more than 900, provided no row is ever inserted with more than 900 bytes of data in those columns. In SQL Server, you can include nonkey columns in a nonclustered index to avoid the maximum index key size of 900 bytes.

3Database objects include objects such as tables, views, stored procedures, user-defined functions, triggers, rules, defaults, and constraints. The sum of the number of all objects in a database cannot exceed 2,147,483,647.

4Although a table can contain an unlimited number of FOREIGN KEY constraints, the recommended maximum is 253. Depending on the hardware configuration hosting SQL Server, specifying additional FOREIGN KEY constraints may be expensive for the query optimizer to process.

5This value is for static lock allocation. Dynamic locks are limited only by memory.

6If a stored procedure accesses more than 8 databases, or more than 2 databases in interleaving, you will receive an error.

7If the table contains one or more XML indexes, the clustering key of the user table is limited to 15 columns because the XML column is added to the clustering key of the primary XML index. In SQL Server, you can include nonkey columns in a nonclustered index to avoid the limitation of a maximum of 16 key columns. For more information, see Index with Included Columns.

8SQL Server supports row-overflow storage which enables variable length columns to be pushed off-row. Only a 24-byte root is stored in the main record for variable length columns pushed out of row; because of this, the effective row limit is higher than in previous releases of SQL Server. For more information, see the "Row-Overflow Data Exceeding 8 KB" topic in SQL Server Books Online.

The following table specifies the maximum sizes and numbers of various objects defined in SQL Server Replication.

SQL Server Replication object

Maximum sizes/numbers SQL Server (32-bit)

Maximum sizes/numbers SQL Server (64-bit)

Articles (merge publication)

256

256

Articles (snapshot or transactional publication)

32,767

32,767

Columns in a table1 (merge publication)

246

246

Columns in a table2 (SQL Server snapshot or transactional publication)

1,000

1,000

Columns in a table2 (Oracle snapshot or transactional publication)

995

995

Bytes for a column used in a row filter (merge publication)

1,024

1,024

Bytes for a column used in a row filter (snapshot or transactional publication)

8,000

8,000

1If row tracking is used for conflict detection (the default), the base table can include a maximum of 1,024 columns, but columns must be filtered from the article so that a maximum of 246 columns is published. If column tracking is used, the base table can include a maximum of 246 columns. For more information on the tracking level, see the "Tracking Level" section of How Merge Replication Detects and Resolves Conflicts.

2The base table can include the maximum number of columns allowable in the publication database (1,024 for SQL Server), but columns must be filtered from the article if they exceed the maximum specified for the publication type.

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