Sybase Adaptive Server IQ 12.4.2, Administration And Performance Manual

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Using command-line switches
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To override these settings for the current server session, specify the server
startup options
-iqmc
(main cache size) and
-iqtc
(temp cache size) to open the
database and reset the defaults. The default sizes are 8MB for the main cache
and 4MB for the temporary cache, which are too low for any active database
use.
Concurrent users
Your license sets the absolute number of concurrent users. However, you must
also set the
-gm
switch. This required switch lets you limit the number of
concurrent user connections on a particular server.
The
-gn
switch sets the number of execution threads that will be used for the
Catalog Store and connectivity while running with multiple users. It applies to
all operating systems and servers.
On Windows NT you need to specify this parameter in the
asiqsrv12
command.
To calculate its value use the following formula:
gn_value = gm_value - (( 2 * num_CPUs ) + 10)
Specify a minimum of 25.
On UNIX platforms, the
start_asiq
utility sets this parameter. See the Adaptive
Server IQ Installation and Configuration Guide for your platform for more
information.
There may be times when you want to tune performance for a particular
operation by limiting the number of user connections to fewer than your license
allows. Alternatively, you may want to use the
-iqgovern
switch to control
query use; see “Concurrent queries.”
Concurrent queries The
-iqgovern
switch lets you specify the number of concurrent queries on a
particular server. This is not the same as the number of connections, which is
controlled by your license. By specifying the
-iqgovern
switch, you can help IQ
optimize paging of buffer data out to disk, and avoid overcommitting memory.
The default value of
-iqgovern
is (2 x the number of CPUs) +10.
Wired memory The
-iqwmem
switch creates a pool of “wired” memory on certain UNIX
platforms only. This memory is locked down so that it cannot be paged. Wired
memory can improve performance on Tru64, HP and Sun platforms. Specify
this switch as the number of megabytes of wired memory.
Warning! Use this switch only if you have enough memory to dedicate some
of it for this purpose. Otherwise, you can cause serious performance
degradation.