Sybase 12.4.2 manual Managing buffer caches, Determining the sizes of the buffer caches, 422

Overview of memory use

Killing processes affects shared memory

Warning! Killing processes on UNIX systems may result in semaphores or shared memory being left behind instead of being cleaned up automatically.

The correct way to shut down an IQ server on UNIX is the stop_asiq utility, described in “Stopping the database server” on page 43. For information on cleaning up after an abnormal exit, see the chapter “Troubleshooting Hints” in Adaptive Server IQ Troubleshooting and Error Messages Guide.

Managing buffer caches

Adaptive Server IQ needs more memory for buffer caches than for any other purpose. Adaptive Server IQ has two buffer caches, one for the IQ Store and one for the Temporary Store. It uses these two buffer caches for all database I/O operations—for paging, for insertions into the database, and for backup and restore. Data is stored in one of the two caches whenever it is in memory. All user connections share these buffer caches. Adaptive Server IQ keeps track of which data is associated with each connection.

Read the sections that follow for in-depth information on managing buffer caches:

•For information on how to calculate your memory requirements, see “Determining the sizes of the buffer caches”

•For information on how to set buffer cache sizes once you know what they should be, see “Setting buffer cache sizes”

Determining the sizes of the buffer caches

The buffer cache sizes you specify for the Main IQ Store and Temporary Store will vary based on several factors. The default values (8MB and 4MB) are too low for most large databases. The actual values required for your application depend on the total amount of physical memory on your system and how much of this memory Adaptive Server IQ, the operating system, and other applications need to do their tasks.

The following diagram shows the relationship between the buffer caches and other memory consumption.

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