DB2 Version 4 Features

IBM introduced many new and useful features with DB2 V4. The highlights of this release are as follows .

Database Administration Features

DB2 Catalog REORG .

User-defined DB2 Catalog indexes.

COPY , RECOVER , and REORG improvements.

Dynamic SQL security improvements.

REFERENCES privilege.

Data sharing.

Type 2 indexes.

User-defined defaults.

Check constraints.

UNIQUE WHERE NOT NULL indexes.

Row-level locking.

Multi-character command prefixes.

Tracking DFSMS concurrent copies in the DB2 Catalog.

Client/Server Features

Stored procedures.

Support for 25,000 distributed connections.

Performance Features

Partition scanning (page range scan).

Query CP parallelism.

Uncommitted read (read-through locks).

No locks on Type 2 indexes.

Programming Features

Outer join.

In-line views (nested tables).

COALESCE function.

Column renaming using AS .

DCLGEN improvements.

DB2 Catalog Impact

Communications Database moved to the DB2 Catalog Database.

3 new tables.

16 tables have one or more new or changed columns .

18 total new columns.

21 total revised columns.