This chapter explains how to improve performance by controlling the location of tables and indexes.
To make the most of physical database tuning, understand these distinctions between logical and physical devices:
The physical disk or physical device is the hardware that stores the data.
A database device or logical device is all or part of a physical disk that has been initialized (with the disk init command) for use by Adaptive Server. A database device can be an operating system file, an entire disk, or a disk partition.
See the Installation Guide and the Configuration Guide for your platform for information about specific operating system constraints on disk and file usage.
A segment is a named collection of database devices used by a database. The database devices that make up a segment can be located on separate physical devices.
A partition is a subset of a table. Partitions are database objects that can be managed independently. You can split partitioned tables, so multiple tasks can access it simultaneously. You can place a partition on a specific segment. If each partition is on a different segment and each segment has its own database device, queries accessing these tables benefit from improved parallelism. See create table in the Reference Manual: Commands and the Transact-SQL Users Guide for more information about creating and using partitions.
Use sp_helpdevice, sp_helpsegment, and sp_helpartition to get more information about devices, segments, and partitions.
