Sybase 12.4.2 manual Options for tuning resource use, Restricting concurrent queries, 448

Options for tuning resource use

Ordinarily, as long as you maintain a reasonable percentage of free space in your IQ Store, you will have enough free space. However, for certain deletions, depending on the size of the data and its distribution among database pages, you may need a large amount of working space. In the case where you are deleting a major portion of your database, and the data is distributed sparsely across many pages, you could temporarily double the size of your database.

Note In other databases, including Adaptive Server IQ Version 11.x, this working space is in a pre-image file. If you are migrating from Version 11.x, you need working space in your IQ Store comparable to the space in your Version 11.x transaction image (TI) file.

Options for tuning resource use

The number of concurrent users of an IQ database, the queries they run, and the processing threads and memory available to them, can have a dramatic impact on performance, memory use, and disk I/O. Adaptive Server IQ provides several options for adjusting resource use to accommodate varying numbers of users and types of queries. Most of these are SET OPTION command options that affect only the current database. A few are command-line options that affect an entire database server.

For more information on all of these options, including parameters, when the options take effect, and whether you can set them for both a single connection and the PUBLIC group, see the Adaptive Server IQ Reference Manual.

Restricting concurrent queries

The -iqgoverncommand-line option takes the opposite approach from the OPTIMIZE_FOR_THIS_MANY_USERS option. Instead of letting the number of users determine resource use, the -iqgovernswitch lets you control the number of concurrent queries on a server. This is not the same as the number of connections, which is controlled by your license.

The -iqgovernswitch optimizes paging of buffer data out to disk, so that memory is used most effectively. The default value of -iqgovernis (2 x the number of CPUs) +10.

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