Sybase 12.4.2 manual Specifying the size of your database, Choosing a Catalog page size, 112

Working with databases

Adaptive Server IQ stores data on disk in compressed form. It uncompresses the data and moves data pages into memory for processing. The IQ page size determines the amount of disk compression and the default I/O transfer block size for the IQ Store. For most applications, this default value is best. For a complete explanation of how the page size and related options affect resource use and performance, see Chapter 12, “Managing System Resources”

Specifying the size of your database

When you create a database, you set the size in MB of the initial IQ database file (the IQ_SYSTEM_MAIN dbspace). This value is defined in the IQ SIZE parameter.

•For raw partitions, you do not specify IQ SIZE; Adaptive Server IQ determines the size of the raw device and sets IQ SIZE to that value.

•For operating system files you can rely on the defaults listed below; or specify a value based on the size of your data, from the required minimum listed below up to a maximum of 128GB, in 1MB increments.

Table 3-1: Default and minimum sizes of IQ and Temporary Stores

				Minimum
			Minimum	Temporary
		Default size	IQ Store	Store size
		of	size when	when
IQ page	Default size	Temporary	specified	specified
size	of IQ Store	Store	explicitly	explicitly
65536	4096000	2048000	4MB	2MB
131072	8192000	4096000	8MB	4MB
262144	16384000	8192000	16MB	8MB
524288	32768000	16384000	32MB	16MB

Choosing a Catalog page size

You can select a page size for the Catalog Store, with the PAGE SIZE option. You should always use 4096 for this option. Each database server can support only one Catalog page size. If you start additional databases on a server, each one acquires the Catalog page size of the first database opened on that server. By always setting this value at 4096 (4KB), you ensure that you will always have an adequate page size for the Catalog.

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