Maximum Capacity Specifications for SQL Server
The following tables specify the maximum sizes and numbers of various objects defined in SQL Server components. To navigate to the table for a SQL Server technology, click on its link:
SQL Server Database Engine Objects
SQL Server Utility Objects
SQL Server Data-tier Application Objects
SQL Server Replication Objects
Database Engine Objects
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. 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 64 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.
SQL Server Utility Objects
The following table specifies the maximum sizes and numbers of various objects that were tested in the SQL Server Utility.
SQL Server Utility object |
Maximum sizes/numbers SQL Server (32-bit) |
Maximum sizes/numbers SQL Server (64-bit) |
|---|---|---|
Computers (physical computers or virtual machines) per SQL Server Utility |
100 |
100 |
Instances of SQL Server per computer |
5 |
5 |
Total number of instances of SQL Server per SQL Server Utility |
2001 |
2001 |
User databases per instance of SQL Server, including data-tier applications |
50 |
50 |
Total number of user databases per SQL Server Utility |
1,000 |
1,000 |
File groups per database |
1 |
1 |
Data files per file group |
1 |
1 |
Log files per database |
1 |
1 |
Volumes per computer |
3 |
3 |
1 SQL Server 2008 R2 Datacenter supports a SQL Server Utility with a maximum of 200 managed instances of SQL Server. SQL Server 2008 R2 Enterprise supports a SQL Server Utility with a maximum of 25 managed instances of SQL Server. For getting started information, see Overview of SQL Server Utility.
SQL Server Data-tier Application Objects
The following table specifies the maximum sizes and numbers of various objects that were tested in the SQL Server data-tier applications (DAC).
SQL Server DAC object |
Maximum sizes/numbers SQL Server (32-bit) |
Maximum sizes/numbers SQL Server (64-bit) |
|---|---|---|
Databases per DAC |
1 |
1 |
Objects per DAC1 |
Limited by the number of objects in a database, or available memory. |
Limited by the number of objects in a database, or available memory. |
1The types of objects included in the limit are users, tables, views, stored procedures, user-defined functions, user-defined data type, database roles, schemas, and user-defined table types.
Replication Objects
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.