HP 3000 Manuals HP 3000 Manuals
Disabling Data Definition
A strategy for improving performance is to disable all data definition
operations while your applications are running. You do this by using
SQLUtil to set the DDL Enabled parameter in the DBECon file to NO. This
is a simple matter if you do all data definition in a development
DBEnvironment. In such a case, you can disable DDL in the production
DBEnvironment only. Disabling data definition
* Allows ALLBASE/SQL to retain sections in memory between
transactions. This means that an application program that
re-executes the same sections again and again does not require
ALLBASE/SQL to read the sections in from disk each time. This can
significantly improve performance.
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NOTE ALLBASE/SQL can retain sections in memory between
transactions. However, if DDL is enabled, ALLBASE/SQL
checks its system catalog once per transaction to see if the
cached section is still valid. When DDL is disabled,
ALLBASE/SQL does not have to check. Disabling DDL still
results in best performance.
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* Makes it impossible to perform data definition and to lock system
catalog pages exclusively.
* Does not inhibit the revalidating of sections. If ALLBASE/SQL
encounters invalid sections, they will be revalidated as
necessary.
* Disables the following statements:
ADD DBEFILE ADD GROUP ADD TO GROUP
ALTER DBEFILE ALTER TABLE CREATE DBEFILE
CREATE DBEFILESET CREATE GROUP CREATE INDEX
CREATE TABLE CREATE VIEW DROP DBEFILE
DROP DBEFILESET DROP GROUP DROP INDEX
DROP TABLE DROP VIEW GRANT
REMOVE FROM GROUP REVOKE START DBE NEWLOG
TRANSFER OWNERSHIP UPDATE STATISTICS
Inhibiting DDL has little effect on performance for applications that do
not re-use the same sections.