Sybase 12.4.2 manual Selecting a device type, Allocating space for databases, 104

Building Your Adaptive Server IQ Databases

The DBA and object owners can grant authority to individual users and to groups of users. For complete information, see Chapter 10, “Managing User IDs and Permissions” You can also use the -gucommand-line option to set the permission level required to create or delete a database.

Selecting a device type

You store databases and database objects on devices. On all platforms, these devices can be operating system files. They can also be portions of a disk, called raw partitions. When you create a database, Adaptive Server IQ determines automatically whether it is a raw partition or a disk file.

In a production environment, raw partition installations may provide increased processing performance and better recovery capabilities. File systems, on the other hand, make it easier to manage your devices, and may be preferable in a development environment.

Note The Catalog Store and the transaction log cannot be on a raw partition.

Allocating space for databases

When to create dbspaces

All Adaptive Server IQ databases are preallocated, whether they reside in a file system or a raw partition.

Each database includes multiple dbspaces. A dbspace is a logical name for a database file. The Catalog Store, the IQ Store, and the Temporary Store all consist of dbspaces. The first dbspace for each store is created automatically when you create the database. You can create additional dbspaces as needed.

When you create and load a table, Adaptive Server IQ distributes the data among all existing dbspaces in that store with any room available. You cannot control how data is distributed among the dbspaces within a store. Once an IQ dbspace is full, you cannot extend it, and you cannot redistribute the data it holds to other dbspaces. You also cannot make dbspaces smaller once you create them.

When possible, create all dbspaces when you create the database, rather than adding them gradually as old ones become full. This approach ensures that your dbspaces will be filled more evenly, and thus helps improve disk I/O.

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