NS_CACHE configuration parameter
Use the NS_CACHE configuration parameter to define the maximum retention time for entries in the Informix® name service caches: the host name/IP address cache, the service cache, the user cache, and the group cache.
- onconfig.std value
- NS_CACHE host=900,service=900,user=900,group=900
- values
- Each of the fields takes an integer value equal to or greater
than 0.
host = Sets the number of seconds to cache information in the host name or IP address cache.
service = Sets the number of seconds to cache information in the service cache.
user = Sets the number of seconds to cache information in the user cache.
group = Sets the number of seconds to cache information in the group cache.
0 = Caching is disabled. The server always gets information from the operating system. You can set an individual cache to 0 or set all name service caches to 0: NS_CACHE 0.
- units
- Seconds
- separators
- Separate values with a comma. Do not include blank spaces.
- takes effect
- After you edit your onconfig file and restart the database server.
- When you reset the value dynamically in your onconfig file by running the onmode -wf command.
- When you reset the value in memory by running the onmode -wm command.
Usage
For looking up and resolving host names (or IP addresses), service names, users (and passwords) or groups, the database server queries the operating system (OS) using appropriate system calls. You can avoid many of these OS lookups by using the Informix name service caching mechanism, which can keep and reuse each retrieved piece of information for a configurable amount of time. You should set the NS_CACHE configuration parameter if your operating system does not provide its own caching.
The server can get information from the cache faster than it does when querying the operating system. However, if you disable one or more of these caches by setting the retention time to 0, the database server queries the operating system for the host, service, user, or group information.
Changes that are made to name services at the operating system level are not immediately reflected in the Informix name server caches: for example, the change of an IP address, a user added to or removed from a group, or a new password. However, you can use the onmode -wf or onmode -wm command to change NS_CACHE information immediately. When you change the value for a particular cache with the onmode -wf or onmode -wm command, the server immediately expires all existing entries in that cache.