## ORACLE SQL Mode

You can operate the MaxDB database system in ORACLE SQL mode. The following sections describe the differences between an Oracle Version 7 database system and a MaxDB (in ORACLE SQL mode) database system.

### Logical Database Structure

There are basic differences between the logical database structures of the Oracle Version 7 database system and MaxDB.

· From a logical point of view, an Oracle database consists of tablespaces, segments, extents, blocks, tables, and data records.

· From a logical point of view, MaxDB essentially consists of the tables in the database catalog and the application data in the form of data records.

All Oracle SQL statements referring to the administration of tablespaces, segments, extents, or blocks are therefore meaningless in MaxDB.

### Consistent Reading/Locking

The consistent reading functionality offered by Oracle can be achieved in MaxDB using locks in isolation level >= 2.

Oracle allows an unlimited number of exclusive row locks. In MaxDB, an escalation takes effect from a certain number of row locks; that is, the whole table is locked. The escalation point in time depends on the defined lock list size.

### Database Procedures/Triggers

· In Oracle, database procedures, database functions, and triggers are defined in PL/SQL (a language similar to ADA).

· In MaxDB, database procedures, database functions, and triggers are defined in a language similar to C.

### DBA Users and Privileges

In contrast to Oracle, database administrators (DBA users) in MaxDB are also subject to the privileges concept and cannot execute DDL statements (such as CREATE INDEX) or DML statements (such as DELETE) if they have not been assigned the corresponding privileges.

### Other Differences

· SQL Syntax Elements

· SQL Statements

· System Tables

· Error Messages