master database only
sysusages contains one row for each disk allocation piece assigned to a database. Each database contains a specified number of database (logical) page numbers.
The create database command checks sysdevices and sysusages to find available disk allocation pieces. One or more contiguous disk allocation pieces are assigned to the database, and the mapping is recorded in sysusages.
See “System tables that manage space allocation” in Chapter 21, “Creating and Managing User Databases” of the System Administration Guide: Volume 2 for more information on sysusages.
With Adaptive Server version 15.0, the device identification
number is stored in the vdevno column and no
longer as part of the vstart column. As a consequence,
you may need to modify scripts and stored procedures that determine
the device identification number based on the earlier schema.
The columns for sysusages are:
Name |
Datatype |
Description |
|---|---|---|
dbid |
smallint |
Database ID |
segmap |
int |
Bitmap of possible segment assignments |
lstart |
int |
First database (logical) page number |
size |
int |
Number of contiguous database (logical) pages |
vstart |
int |
Starting virtual page number |
pad |
smallint null |
Unused |
unreservedpgs |
int null |
Free space not part of an allocated extent |
crdate |
datetime null |
Creation date |
vdevno |
int |
Device identification number |
Unique clustered index on dbid, lstart
Unique nonclustered index on vdevno, vstart
