Oracle7 Server Utilities

Using Oracle Version 6 Export Files

This section describes the guidelines and restrictions that apply when importing data from an Oracle Version 6 database into the Oracle7 Server. Additional information may be found in the Oracle7 Server Migration manual.

CHAR columns

Oracle Version 6 CHAR columns are automatically converted into the Oracle VARCHAR2 datatype.

If you pre-create tables from prepared scripts, then the CHAR columns are created as Oracle fixed-width columns instead of the desired VARCHAR2 (variable-width) columns. If you modify the scripts to create VARCHAR2 columns, however, the the columns will be created.

LONG columns

Memory limitations may make it impossible to Import some LONG columns when the values contained in those columns are extremely long. Although Export can output LONG data in sections, Import requires contiguous memory.

Syntax of Integrity Constraints

The SQL syntax for integrity constraints in Oracle Version 6 is different from the Oracle7 Server syntax. Import automatically adjusts the declaration so that integrity constraints are properly imported into the Oracle7 Server, unless Version 6-compatibility mode is in effect.

Status of Integrity Constraints

Oracle Version 6 integrity constraints are imported with the status recorded in the export file. In Version 6, all constraints other than NOT NULL are disabled, and that status is recorded in the export file. NOT NULL constraints imported into Oracle are either ENABLED or DISABLED, depending on the status recorded in the export file.

Length of DEFAULT Column Values

A table with a default column value that is longer than the maximum size of that column generates the following error on import to Oracle7:

ORA-1401: inserted value too large for column

Oracle Version 6 did not check the columns in a CREATE TABLE statement to be sure they were long enough to hold their DEFAULT values so these tables could be imported into a Version 6 database. The Oracle7 Server does make this check, however. As a result, tables that could be imported into a Version 6 database may not import into Oracle7.

If the DEFAULT is a value returned by a function, then the column must be large enough to hold the maximum value that can be returned by that function. Otherwise, the CREATE TABLE statement recorded in the export file produces an error on import.

Note: The maximum value of the USER function increased in the Oracle7 Server, so columns with a default of USER may not be long enough. To determine the maximum size that the USER function will return, execute the following SQL command:

		DESCRIBE user_sys_privs

The length shown for the USERNAME column is the maximum length returned by the USER function.