SQL/MX 2.x Installation and Management Guide (G06.24+, H06.03+)

Adding, Altering, and Dropping SQL/MX Database
Objects
HP NonStop SQL/MX Installation and Management Guide—523723-004
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Dropping Indexes
Steps for Dropping a Constraint
1. Start an MXCI session. Enter a LOG command to initiate a log file for statements
and commands entered in this session. Keep the log for your records.
2. Determine the name of the table for which you want to drop the constraint.
3. Use the DISPLAY USE OF command to identify which user modules are
associated with this object. See the similarity check criteria in the SQL/MX
Programming Manual for C and COBOL and the SQL/MX Programming Manual for
Java to determine if your changes are likely to cause similarly check to fail and
force automatic recompilation. If they will, you should SQL compile these modules
after making the changes to avoid expensive automatic recompilations at run time.
SQL applications that are running while you make these changes will still undergo
automatic recompilation.
For information about explicit and automatic recompilation, see the SQL/MX
Programming Manual for C and COBOL and the SQL/MX Programming Manual for
Java. For information about using DISPLAY USE OF, see Checking Module
Dependencies With DISPLAY USE OF on page 11-20 and the SQL/MX Reference
Manual.
4. Enter the ALTER TABLE DROP CONSTRAINT statement.
5. Revise the application source code as needed to reflect your changes to the
database. Process and compile the updated source file. For more information, see
the SQL/MX Programming Manual for C and COBOL and the SQL/MX
Programming Manual for Java.
For more information and examples of dropping constraints, see the SQL/MX
Reference Manual.
Dropping Indexes
To drop an index, use the DROP INDEX statement.
This statement purges the physical file that contains the index and eliminates the
access path to the underlying table. The RESTRICT option, by default, will not allow an
index to be dropped if it is being used to validate a constraint. The CASCADE option, if
specified, will drop both the index and any constraints using the index for validation.
Dropping an index invalidates programs that depend on index access path. When you
drop an index, you should explicitly SQL compile the dependent programs to return the
application to a valid state and to avoid expensive automatic recompilations.
For more information, see the SQL/MX Reference Manual.
Steps for Dropping an Index
1. Start an MXCI session. Enter a LOG command to initiate a log file for statements
and commands entered in this session. Keep the log for your records.