Overview of System Catalogs and System Views

System catalogs store the structured metadata of GaussDB. They are the source of information used by GaussDB to control system running and are a core component of the database system.

System views provide ways to query system catalogs and internal database status.

System catalogs and system views are visible to either system administrators or all users. Some of the following system catalogs and views have marked the need of administrator permissions. They are accessible only to administrators.

You can delete and re-create system catalogs, add columns to them, and insert and update values in them, but doing so may make system information inconsistent and cause system faults. Generally, users should not modify system catalogs or system views, or rename their schemas. They are automatically maintained by the system.

• You are advised not to modify the permissions on system catalogs or system views.
• Do not add, delete, or modify system catalogs because doing so will result in exceptions or even cluster unavailability.
• System catalogs and views do not support foreign key-related columns.
• For details about column types in system catalogs and system views, see Data Types.
• For ADM views, the accessed objects are all objects of this type in the database. Therefore, unified permission management is required for ADM views. By default, only the system administrator has the permission to access ADM views. Some ADM view data comes from public and non-sensitive columns in base tables. For DB views, the objects that the current user has the permission to access in the database can be queried. Common users can access these views. For MY views, objects to which the current user belongs can be queried. Common users can access these views.