Setting Buffer Cache Sizes - Sybase Adaptive Server IQ 12.4.2 Administration And Performance Manual

Memory Use
Memory remaining for the main and
temp buffer caches
Main_Cache_Memory_Mb setting:
60% of memory remaining for
buffer caches
Temp_Cache_Memory_Mb setting:
40% of memory remaining for
buffer caches

Setting buffer cache sizes

Method
MAIN_CACHE_MEMORY_
and
MB
TEMP_CACHE_MEMORY_
database options
MB
Memory available
using raw partitions
Amount
Used Queries
675
405
270
a
Minimum operating system use for Windows NT is 30MB
As shown in the table, you should have one set of values for your buffer caches
when primarily inserting into the database, another set when primarily
querying the database, each differing from a typical mixed load of inserting and
querying. To change the cache sizes, see "Setting buffer cache sizes".
Remember that the cache size options do not take effect until you stop and
restart the database.
By default, Adaptive Server IQ sets the size of the main and temporary buffer
caches to 8MB and 4MB respectively. Most applications will require much
higher values (limited by the total amount of physical memory).
Several options and server switches can affect buffer cache sizes:
Table 12-2: Methods of adjusting buffer cache sizes
When to use it
Normal way to set buffer
cache sizes. Database
must be open to set these
values.
CHAPTER 12 Managing System Resources
Memory available
using "cooked" file
systems
Inserts Queries
828 397
497 238
331 159
How long the setting is
effective
From the next time the
database is restarted, until
you reset these options, or
temporarily override them
with server switches
Inserts
550
330
220
For more
information, see
"Setting buffer cache
size database options"
on page 428
427