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What is a DataServer Schema Holder?

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What is a DataServer Schema Holder?
INTRODUCTION:
=============
This entry describes what a DataServer schema holder is.


WHY YOU NEED TO KNOW THIS:
===========================
As a first step in DataServer development it is important to
understand what the purpose of a schema holder is and
how to create one.


WHAT IT IS:
===========
A schema holder is an empty PROGRESS database with limited Data
Dictionary functions.

A schema holder contains schema definitions for one or more data
managers. Data manager is what some call a "backend" or "the
under lying database". Progress supports many data managers such as
Oracle, Sybase, C-ISAM, RDB, RMS, Object Access, etc.

The schema holder contains no user or application data.

The schema holder maps to a data manager's data definitions with some
additions to provide PROGRESS 4-GL functionality.

PROGRESS accesses the schema holder at the beginning of a runtime
session for data definition aka. schema caching AND when it compiles
procedures.

ONLINE PROCEDURES OR UTILITIES:
===============================
A schema holder is created manually unless a particular DataServer has
an automated utility. To manually create a schema holder, create an
empty single-volume PROGRESS database. Second go to the PROGRESS
Data Dictionary, Admin, Oracle Utilities, Create Schema Holder.
This creates a schema holder from an empty PROGRESS database.
Some DataServers have supplemental programs that automate this process
as one of its functions. An example of this in PROGRESS Version 6.3E
and later is the ORACLE DataServer's "protoora.p" module.

REFERENCES TO WRITTEN DOCUMENTATION
====================================
Database Gateways Guide, see Index for specific DataServer
DataServer Guide to ORACLE
DataServer Guide to Sybase
DataServer Guide to C-ISAM

Progress Software Technical Support Note # 13251