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Overview of memory use
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• On Solaris systems with more than 4GB of memory, the file system buffer
cache competes with IQ's buffer cache less, so you may decrease
performance by turning off file system buffering.
• On NT systems, under certain loads and configurations, disabling the file
system buffer cache can likely improve performance.
As of Version 12.4.2, file system buffering is turned off by default for newly
created IQ databases.
To disable file system buffering for existing databases, issue the following
statement:
SET OPTION "PUBLIC".OS_FILE_CACHE_BUFFERING = OFF
You can only set this option for the PUBLIC group. You must shut down the
database and restart it for the change to take effect.
Note Solaris does not have a kernel parameter to constrain the size of its file
system buffer cache. Over time, the file system buffer cache grows and
displaces the IQ buffer cache pages, leading to excess operating system paging
activity and reduced IQ performance.
NT can bias the paging algorithms to favor applications at the expense of the
file system. This bias is recommended for IQ performance. See Chapter 5,
“Performance and Tuning Tasks” in the Adaptive Server IQ Installation and
Configuration Guide for Windows NT for details.
Other ways to get more memory
In certain environments, you may be able to adjust other options to make more
memory available to Adaptive Server IQ.
Options for Java-enabled databases
The JAVA_HEAP_SIZE option of the SET OPTION command sets the maximum
size (in bytes) of that part of the memory that is allocated to Java applications
on a per connection basis. Per connection memory allocations typically consist
of the user's working set of allocated Java variables and Java application stack
space. While a Java application is executing on a connection, the per
connection allocations come out of the fixed cache of the database server, so it
is important that a run-away Java application is prevented from using up too
much memory.