Sybase 12.4.2 manual Specifying page size, Setting buffer cache size server switches, 429

CHAPTER 12 Managing System Resources

3Make sure all users are disconnected from the database, and stop the database.

•If the -gacommand-line switch is set, the database shuts down automatically after the last user disconnects.

•If -gais not set, stop the database, by using the stop_asiq utility on UNIX, or by clicking Shutdown on the database server display on Windows NT.

4Restart the database. The new cache sizes are now in effect.

Note It is important to have an appropriate PUBLIC setting of the cache size options. Otherwise, when the database server is restarted they will revert to the default settings, which are far too low for most applications.

Setting buffer cache size server switches

Normally you change the buffer cache sizes by setting the

MAIN_CACHE_MEMORY_MB and TEMP_CACHE_MEMORY_MB database options. However, if you set these parameters to a value that is higher than your system will accommodate, you will not be able to open the database. If this occurs, use the server startup options -iqmc and -iqtc to change the current buffer cache sizes. These parameters only remain in effect while the server is running, so you still need to set the buffer cache size database options.

Specifying page size

When you create a database, you set its page size. This parameter, in conjunction with the size of the buffer cache, determines memory use and disk I/O throughput for that database.

Setting the page size

Adaptive Server IQ swaps data in and out of memory in units of pages. When you create a database, you specify a separate page size for the Catalog Store and the IQ Store. The Temporary Store has the same page size as the IQ Store.

For IQ page size recommendations for the best performance, see “Choosing an

IQ page size” on page 111.

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