MobiLink Synchronization User's Guide
  Synchronization Techniques
    Maintaining unique primary keys
      Maintaining unique primary keys using global autoincrement

Declaring default global autoincrement

You can set default values in your database by selecting the column properties in Sybase Central, or by including the DEFAULT GLOBAL AUTOINCREMENT phrase in a CREATE 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, especially if our column is not of type INT or BIGINT, it is best to specify the partition size explicitly.

For example, the following statement creates a simple 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.

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