System-defined segments

When you first create a database, Adaptive Server creates three segments in the database, as described in Table 23-1.

**Table 23-1: System-defined segments**
Segment	Function
system	Stores the database’s system tables
logsegment	Stores the database’s transaction log
default	Stores all other database objects—unless you create additional segments and store tables or indexes on the new segments by using create table...on segment_name or create index...on segment_name

If you create a database on a single database device, the system, default, and logsegment segments label the same device. If you use the log on clause to place the transaction log on a separate device, the segments resemble those shown in Figure 23-1.

Figure 23-1: System-defined segments

Although you can add and drop user-defined segments, you cannot drop the default, system, or log segments from a database. A database must have at least one default, system-defined, and log segment.