Sybase Adaptive Server IQ 12.4.2, Administration And Performance Manual

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CHAPTER 12 Managing System Resources
427
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.
Setting buffer cache sizes
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
Memory remaining for the main and
temp buffer caches 675 828 397 550
Main_Cache_Memory_Mb setting:
60% of memory remaining for
buffer caches 405 497 238 330
Temp_Cache_Memory_Mb setting:
40% of memory remaining for
buffer caches 270 331 159 220
Memory available
using raw partitions
Memory available
using "cooked" file
systems
Memory Use
Amount
Used
Queries Inserts Queries Inserts
Method When to use it
How long the setting is
effective For more
information, see
MAIN_CACHE_MEMORY_
MB
and
TEMP_CACHE_MEMORY_
MB
database options
Normal way to set buffer
cache sizes. Database
must be open to set these
values. From the next time the
database is restarted, until
you reset these options, or
temporarily override them
with server switches “Setting buffer cache
size database options”
on page 428