Maximum capacity specifications for SQL Server

Applies to: SQL Server (all supported versions)

This article shows maximum sizes and numbers of various objects defined in SQL Server 2016 (13.x) and later. If you want to view edition limits, see Compute capacity limits by edition of SQL Server.

For SQL Server 2014 (12.x), see Maximum capacity specifications for SQL Server 2014.

Database Engine objects

Maximum values of various objects defined in SQL Server databases, or referenced in Transact-SQL statements.

SQL Server Database Engine object Maximum values for SQL Server (64-bit) Additional Information
Batch size 65,536 * (network packet size) Network packet size is the size of the tabular data stream (TDS) packets used to communicate between the relational Database Engine and applications. The default packet size is 4 KB, and is controlled by the network packet size configuration option.
Byte length of a string containing Transact-SQL statements (batch size) 65,536 * (network packet size) Network packet size is the size of the tabular data stream (TDS) packets used to communicate between the relational Database Engine and applications. The default packet size is 4 KB, and is controlled by the network packet size configuration option.
Bytes per short string column 8,000
Bytes per GROUP BY, ORDER BY 8,060
Bytes per index key 900 bytes for a clustered index. 1,700 bytes for a nonclustered index. For SQL Server 2014 (12.x) and earlier, all versions supported 900 bytes for all index types. The maximum number of bytes in a clustered index key can't exceed 900. For a nonclustered index key, the maximum is 1,700 bytes.

You can define a key using variable-length columns whose maximum sizes add up to more than the limit. However, the combined sizes of the data in those columns can never exceed the limit.

In a nonclustered index, you can include extra non-key columns, and they don't count against the size limit of the key. The non-key columns might help some queries perform better.
Bytes per index key for memory-optimized tables 2,500 bytes for a nonclustered index. No limit for a hash index, as long as all index keys fit in-row. On a memory-optimized table, a nonclustered index can't have key columns whose maximum declared sizes exceed 2,500 bytes. It doesn't matter if the actual data in the key columns would be shorter than the maximum declared sizes.

For a hash index key, there's no hard limit on size.

For indexes on memory-optimized tables, there's no concept of included columns, since all indexes inherently cover all columns.

For a memory-optimized table, even though the row size is 8,060 bytes, some variable-length columns can be physically stored outside those 8,060 bytes. However, the maximum declared sizes of all key columns for all indexes on a table, plus any additional fixed-length columns in the table, must fit in the 8,060 bytes.
Bytes per foreign key 900
Bytes per primary key 900
Bytes per row 8,060 SQL 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. For more information, see Large Row Support.
Bytes per row in memory-optimized tables 8,060 Memory-optimized tables on SQL Server 2016 (13.x) and later support off-row storage. Variable length columns are pushed off-row if the maximum sizes for all the columns in the table exceeds 8,060 bytes; this action is a compile-time decision. Only an 8-byte reference is stored in-row for columns stored off-row. For more information, see Table and Row Size in Memory-Optimized Tables.
Bytes in source text of a stored procedure Lesser of batch size or 250 MB
Bytes per varchar(max), varbinary(max), xml, text, or image column 2^31-1
Characters per ntext or nvarchar(max) column 2^30-1
Clustered indexes per table 1
Columns in GROUP BY, ORDER BY Limited only by number of bytes
Columns or expressions in a GROUP BY WITH CUBE or GROUP BY WITH ROLLUP statement 10
Columns per index key 32 If the table contains one or more XML indexes, the clustering key of the user table is limited to 31 columns because the XML column is added to the clustering key of the primary XML index. In SQL Server you can include non-key columns in a nonclustered index, to avoid the limitation of a maximum of 32 key columns. For more information, see Create Indexes with Included Columns.
Columns per foreign key or primary key 32
Columns per INSERT statement 4,096
Columns per SELECT statement 4,096
Columns per table 1,024 Tables that include sparse column sets include up to 30,000 columns. See sparse column sets.
Columns per UPDATE statement 4,096 Different limits apply to sparse column sets.
Columns per view 1,024
Connections per client Maximum value of configured connections
Database size 524,272 terabytes
Databases per instance of SQL Server 32,767
Filegroups per database 32,767
Filegroups per database for memory-optimized data 1
Files per database 32,767
File size (data) 16 terabytes
File size (log) 2 terabytes
Data files for memory-optimized data per database 4,096 in SQL Server 2014 (12.x). The limit is less strict on SQL Server 2016 (13.x) and later.
Delta file per data file for memory-optimized data 1
Foreign key table references per table Outgoing = 253.
Incoming = 10,000.
For restrictions, see Create Foreign Key Relationships.
Identifier length (in characters) 128
Instances per computer 50 instances on a stand-alone server.

25 failover cluster instances when using a shared cluster drive as storage.

50 failover cluster instances with SMB file shares as the storage option.
Indexes per memory-optimized table 999 starting SQL Server 2017 (14.x) and in Azure SQL Database.

8 in SQL Server 2016 (13.x) and SQL Server 2014 (12.x).
Locks per connection Maximum locks per server
Locks per instance of SQL Server Limited only by memory This value is for static lock allocation. Dynamic locks are limited only by memory.
Nested stored procedure levels 32 If a stored procedure accesses more than 64 databases, or more than two databases in interleaving, you'll receive an error.
Nested subqueries 32
Nested transactions 4,294,967,296
Nested trigger levels 32
Nonclustered indexes per table 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
Number of grouping sets generated by operators in the GROUP BY clause 4,096
Parameters per stored procedure 2,100
Parameters per user-defined function 2,100
REFERENCES per table 253
Rows per table Limited by available storage
Tables per database Limited by total number of objects in a database Objects include tables, views, stored procedures, user-defined functions, triggers, rules, defaults, and constraints. The sum of the number of all objects in a database can't exceed 2,147,483,647.
Partitions per partitioned table or index 15,000
Statistics on non-indexed columns 30,000
Tables per SELECT statement Limited only by available resources
Triggers per table Limited by number of objects in a database Objects include tables, views, stored procedures, user-defined functions, triggers, rules, defaults, and constraints. The sum of the number of all objects in a database can't exceed 2,147,483,647.
User connections 32,767
XML indexes 249

SQL Server Utility objects

Maximum values of various objects that were tested in the SQL Server Utility.

SQL Server Utility object Maximum values for SQL Server (64-bit) Additional information
Computers (physical computers or virtual machines) per SQL Server Utility 100
Instances of SQL Server per computer 5
Total number of instances of SQL Server per SQL Server Utility 200 The maximum number may vary based on the hardware configuration of the server. For getting started information, see SQL Server Utility Features and Tasks. SQL Server Utility control point isn't available in every edition of SQL Server. You can read about the features supported by each edition of SQL Server 2019, SQL Server 2017, and SQL Server 2016.
User databases per SQL Server instance, including data-tier applications 50
Total number of user databases per SQL Server Utility 1,000
File groups per database 1
Data files per file group 1
Log files per database 1
Volumes per computer 3

SQL Server Data-tier application objects

Maximum values of various objects that were tested in the SQL Server data-tier applications (DAC).

SQL Server DAC object Maximum values for SQL Server (64-bit) Additional information
Databases per DAC 1
Objects per DAC Limited by the number of objects in a database, or available memory. 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

Maximum values of various objects defined in SQL Server Replication.

SQL Server Replication object Maximum values for SQL Server
(64-bit)
Additional information
Articles (merge publication) 2,048
Articles (snapshot or transactional publication) 32,767
Columns in a table (merge publication) 246 If 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.
Columns in a table (SQL Server snapshot or transactional publication) 1,000 The base table can include the maximum number of columns allowable in the SQL Server publication database (1,024), but columns must be filtered from the article if they exceed the maximum specified for the publication type.
Columns in a table (Oracle snapshot or transactional publication) 995 The base table can include the maximum number of columns allowable in the SQL Server publication database (1,024), but columns must be filtered from the article if they exceed the maximum specified for the publication type.
Bytes for a column used in a row filter (merge publication) 1,024
Bytes for a column used in a row filter (snapshot or transactional publication) 8,000

See also