ODBC Server Installation and Management Manual

Installing the NonStop ODBC Server
HP NonStop ODBC Server Installation and Management Manual—429395-002
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Dynamic Configuration
Not every utility statement causes catalog integrity to be checked, however, which
allows you more flexibility in the sequencing and allows you to effect an UPDATE by
performing a REMOVE followed by an INSERT.
When configuring the NonStop ODBC Server involves making changes to the NonStop
ODBC Server catalogs—and it usually does—do the following:
1. Make the desired configuration changes.
2. Use the VALIDATE utility statement to check NonStop ODBC Server catalog
integrity.
3. If Step 2 produces a problem report, decide how to solve the problem or problems.
In some cases, you can use the ADD TABLE statement to affect the needed
changes. An example is a case in which a SQL/MP user creates a table T in
catalog C after a NonStop ODBC Server catalog has been built for C (T does not
appear in the NonStop ODBC Server catalog).
After you have fixed the problem or problems, repeat Step 2.
Dynamic Configuration
A powerful feature of the NonStop ODBC Release 2 Server is the ability to change the
configuration of a running NonStop ODBC Server system—and to have the changes
take effect—without needing to stop and restart the system. The method used for
handling configuration changes is based on the system components checking for
configuration changes at a system-defined interval. The checking interval is set by the
system administrator in the CHECK_INTERVAL_SECONDS value in the system
configuration values table. See the description of ZNSSCFG (system configuration
values) under “NonStop ODBC Server Mapping Tables,” in the NonStop ODBC Server
Reference Manual for more details.
Two important concepts that relate to dynamic configuration are polling and the
Configuration Update option:
Polling
Dynamic reconfiguration is based on the concept of system components polling for
system configuration changes and then taking action as a result of any change that
might affect them. Having a fixed polling interval reduces the effect on the system of
having components continually checking for configuration changes, but it also means
that a configuration change does not take effect until a component polls for a change.
As an example, consider a NonStop ODBC server process to which a user, User A,
has been connected at time T1 with profile P1, as illustrated in Figure 2-2. At some
point during the session, time T2, the profile is changed (profile P2). The server does
not check to see if the profile has changed for the next connection until the specified
polling interval has expired. If User A reconnects at time T3 to the same server, the
server continues to use the P1 profile definition, but if User A reconnects after the
polling interval has expired, at time T4, the new P2 profile definition is in effect.