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Sequence Properties (General Page)

Creates a sequence object and specifies its properties. A sequence is a user-defined schema bound object that generates a sequence of numeric values according to the specification with which the sequence was created. The sequence of numeric values is generated in an ascending or descending order at a defined interval and can be configured to restart (cycle) when exhausted. Sequences, unlike identity columns, are not associated with specific tables. Applications refer to a sequence object to retrieve its next value. The relationship between sequences and tables is controlled by the application. User applications can reference a sequence object and coordinate the values across multiple rows and tables.

Unlike identity columns values which are generated at the time of insert, an application can obtain the next sequence number without inserting the row by calling the NEXT VALUE FOR function. Use sp_sequence_get_range to get multiple sequence numbers at once.

For information and scenarios that use both CREATE SEQUENCE and the NEXT VALUE FOR function, see Sequence Numbers.

This page is accessed in two ways: either by right-clicking Sequences in Object Explorer and clicking New Sequence, or by right-clicking an existing sequence and clicking Properties. When you right-click an existing sequence and click Properties, the options are not editable. To change the sequence options use the ALTER SEQUENCE (Transact-SQL) statement or drop and recreate the sequence object.

Sequence name

Enter the sequence name here.

Sequence schema

Specify the schema that will own this sequence.

Data type

A sequence can be defined as any integer type. This includes:

Data type

Range

tinyint

0 to 255

smallint

-32,768 to 32,767

int

-2,147,483,648 to 2,147,483,647

bigint

-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807

  • decimal or numeric with a scale of 0.

  • Any user-defined data type (alias type) that is based on one of these types.

Precision

For decimal or numeric data types, specify the precision. (The scale is always 0.)

Start with value

The first value that will be returned by the sequence object. The START value must be a value that is less than or equal to the maximum and greater than or equal to the minimum value of the sequence object. The default start value for a new sequence object is the minimum value for an ascending sequence object and the maximum value for a descending sequence object.

Increment by

The value that is used to increment (or decrement if negative) the value of the sequence object for each call to the NEXT VALUE FOR function. If the increment is a negative value the sequence object is descending, otherwise, it is ascending. The increment cannot be 0.

Minimum value

Specifies the bounds for sequence object. The default minimum value for a new sequence object is the minimum value of the data type of the sequence object. This is zero for the tinyint data type and a negative number for all other data types.

Maximum value

Specifies the bounds for sequence object. The default maximum value for a new sequence object is the maximum value of the data type of the sequence object.

Cycle-sequence will restart on reaching limit

Select to allow the sequence object to restart from the minimum value (or maximum for descending sequence objects) when its minimum or maximum value is exceeded.

Note Note

Cycling does not restart from the start value but rather from the minimum/maximum value.

Cache options

Creating a cache of sequence values can increase performance for applications that use sequence objects by minimizing the number of disk IOs that are required to create sequence numbers.

  • Default cache size - The Database Engine will select a size, however users should not rely upon the selection being consistent. Microsoft might change the method of calculating the cache size without notice.

  • No cache - SQL Server will not cache sequence numbers.

  • Cache with size - SQL Server will cache sequence values. SQL Server keeps track of the current value and the number of values left in the cache. Therefore, the amount of memory that is required to store the cache is always two instances of the data type of the sequence object

When created with the CACHE option, an unexpected shutdown, such as a power failure, can lose the sequence numbers in the cache.

For additional information about the create sequence options, see CREATE SEQUENCE (Transact-SQL).

Requires CREATE SEQUENCE, ALTER, or CONTROL permission on the SCHEMA.

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