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Threaded Code Design for Multiple DDL Clauses

IP.com Disclosure Number: IPCOM000099655D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 96K

Publishing Venue

IBM

Related People

Boykin, JR: AUTHOR [+4]

Abstract

Data Definition Language (DDL) statements (CREATE TABLE, ALTER TABLE, DROP INDEX, COMMENT ON TABLE, etc.) define a set of database objects. Referential constraints define restrictive relationships between one or more database tables. SQL permits both DDL and referential constraint relationships to be defined within one SQL statement.

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Threaded Code Design for Multiple DDL Clauses

       Data Definition Language (DDL) statements (CREATE TABLE,
ALTER TABLE, DROP INDEX, COMMENT ON TABLE, etc.) define a set of
database objects.  Referential constraints define restrictive
relationships between one or more database tables.  SQL permits both
DDL and referential constraint relationships to be defined within one
SQL statement.

      The context of this disclosure is OS/2* threaded code
architecture.  This architecture describes an Access Section,
composed in part of data objects and threads.  The data objects
contain information about the data being operated on, while the
threads contain operators that direct the execution upon the data.

      Present architecture defines all processing for a single DDL
statement to be contained within one threaded code operator.  In
addition to ADD column clauses, DDL statements may now contain two
primary and an unlimited number of foreign key clauses.  DDL
statements, therefore, can no longer be processed efficiently with
one threaded code operator.  Savepoints, currently generated per DDL
operator, are now needed on a statement basis.

      The following operators are generated within the OS/2 Extended
Edition Database Manager during DDL statement compilation:
 IDD - resets the authorization flag and starts a savepoint.
 DD1 - performs one of the DDL functions through calls to the
appropriate Catalog Services or Application Plan Manager routine.
(The DD1 operator replaces the previously disclosed DDL operator.
Access sections compiled under Release 1.0 and 1.1 are still
supported by the DDL operator.)
    Multiple DD1s may exist in a statement.  The DD1 function is
defined as:
                 DD1 (Index, Length, DDL opcode structure)
               where
                 Index  - type of DDL statement
                     0 = Alter Table (add column)
                     1 = Comment on Column
                      2 = Comment on Table
                      3 = Create Index
                      4 = Create Table
                      5 = Create View (run time)
                      6 = Drop Index
                      7 = Drop Table
                      8 = Drop View
                      9 = Drop Program
                     10 = Create View (pre-processing)
                     11 = Create/Alter Table (Create Primary
                          Key)
                     12 = Alter Table (Drop Primary Key)
                 Length - length of the DDL structure

      DDL op code structure:
                        - authorization id of t...