An access policy establishes rules that limit user or program access to specified segments. Access policies increase application performance because they limit the number of segments that a user or program can query.
Access policies reduce the amount of data that the database retrieves, which improves both query performance and application response time. When a user or program queries the database, the database performs operations on only the segments specified in the user or program access policy.
Before you create access policies based on program or user, create a default access policy. The default access policy applies to anything that can query the database. Access policies that you create for specific programs or users override the default access policy.