UltraLite Database User's Guide
   Synchronization for UltraLite Applications
    Designing synchronization for your UltraLite database
      Maintaining primary key uniqueness

Declaring default global autoincrement columns

You declare default column values in the Adaptive Server Anywhere reference database. When you build your UltraLite application, your UltraLite database inherits the default column value. You can set default values in your reference database by selecting the column properties in Sybase Central, or by including the DEFAULT GLOBAL AUTOINCREMENT phrase in a TABLE or ALTER TABLE statement.

Optionally, the partition size can be specified in parentheses immediately following the AUTOINCREMENT keyword. The partition size may be any positive integer, although the partition size is generally chosen so that the supply of numbers within any one partition will rarely, if ever, be exhausted.

For columns of type INT or UNSIGNED INT, the default partition size is 2¹⁶  = 65536; for columns of other types the default partition size is 2³² = 4294967296. Since these defaults may be inappropriate it is best to specify the partition size explicitly.

For example, the following statement creates a simple reference table with two columns: an integer that holds a customer identification number and a character string that holds the customer's name.

CREATE TABLE customer (
   id   INT          DEFAULT GLOBAL AUTOINCREMENT (5000),
   name VARCHAR(128) NOT NULL,
   PRIMARY KEY (id)
)

In the above example, the chosen partition size is 5000.

Default partition sizes for some data types are different in UltraLite applications than in Adaptive Server Anywhere databases. Declare the partition size explicitly if you wish the reference database to behave in the same manner as your UltraLite application.

For more information on GLOBAL AUTOINCREMENT, see CREATE TABLE statement.