Overview

The information used by Pervasive PSQL and its components is stored in special tables called system tables.

Caution
Do not attempt to modify system tables with DELETE, UPDATE, or INSERT statements, or user-defined triggers. System tables should never be altered.

Do not write your applications to query system tables directly. Some columns in system tables may not be documented. Your application can retrieve information stored in system tables by using any of the following methods:

System Stored Procedures

Transact-SQL statements and functions

Functions provided in the Pervasive PSQL application programming interfaces (API)

Note that the Pervasive PSQL APIs are documented in the Pervasive PSQL Software Development Kit (SDK). The SDK components are compatible with the database engine from release to release. The format of the system tables depends on the internal architecture of the Pervasive PSQL database engine. The architecture may change from release to release. Application that directly access undocumented columns of system tables may have to be changed if the internal architecture of Pervasive PSQL changes.

For each system table, the following table indicates the name of the associated file and briefly describes the system table's contents.

Note
Some data in the system tables cannot be displayed. User passwords, for example, display in encrypted form.

Table C-1 System Tables
System Table	Dictionary File	Contents
X$File	FILE.DDF	Names and locations of the tables in your database.
X$Field	FIELD.DDF	Column and named index definitions.
X$Index	INDEX.DDF	Index definitions.
X$Attrib	ATTRIB.DDF	Column attributes definitions.
X$View	VIEW.DDF	View definitions.
X$Proc	PROC.DDF	Stored procedure definitions.
X$User	USER.DDF	User names, group names, and passwords.
X$Rights	RIGHTS.DDF	User and group access rights definitions.
X$Relate	RELATE.DDF	Referential integrity (RI) information.
X$Trigger	TRIGGER.DDF	Trigger information.
X$Depend	DEPEND.DDF	Trigger dependencies such as tables, views, and procedures.
X$Types	TYPES.DDF	Reserved for future use.

Pervasive PSQL creates all of the system tables when you create a database.

Two other system tables that you may encounter are VARIANT.DDF and OCCURS.DDF.These two system files are used for COBOL support and do not require any direct intervention by a user. Future versions of the utilities for COBOL may implement a different architecture, in which case these system tables may no longer be required. See also SQL Access for COBOL Applications .