ODBC Server Reference Manual

Architecture Overview
HP NonStop ODBC Server Reference Manual—429151-002
2-22
Name Mapping
The following is an example involving usernames. There are several alias usernames
by which a client can connect. The name “SQL_JONES” illustrates using essentially
the same name on both the client and server side (which is useful if the named person
does some work on a PC and some work on the NonStop server). The other “Joneses”
represent two aliases that also map to the logical username “SQL_JONES.” The
difference is that each alias is mapped to a different profile.
The subsequent two aliases permit the database administrator to login as either “DBO”
or “ADMINSTRATOR,” both of which map to the same logical username, Guardian
username, and profile.
Alias Logical Guardian
Username Usename Profile Username
SQL_JONES SQL_JONES CLASS2 SQL.JONES
JONES_CACHE_ON SQL_JONES CLASS_CACHE_ON SQL.JONES
JONES_CACHE_OFF SQL_JONES CLASS_CACHE_OFF SQL.JONES
DBO DBO ADMIN SUPER.MGR
ADMINSTRATOR DBO ADMIN SUPER.MGR
GUEST SQL_GUEST DEFAULT SQL.GUEST
The particular choice of relationships between these objects—what is related to what
and in what ratio the relationships exist—is based on several factors. In general, all
attributes of a client are associated with the alias username, when possible, to allow
maximum flexibility. A few attributes are associated with the logical or Guardian
username for simplicity or performance.
Name Mapping
A principal job of the NonStop ODBC Server is to map (translate) several types of
names, including those of databases, users, tables, and columns, between the client
and server environments. The requirements for mapping—to be flexible, easy to
maintain, and to perform well—usually conflict. The NonStop ODBC Server uses a
table look-up scheme. The table is a NonStop SQL/MP table. Each row represents one
or more relationships between a client and a SQL/MP name.
NonStop ODBC Server Catalogs
The NonStop ODBC Server catalogs are sets of NonStop SQL/MP tables and views
maintained by the NonStop ODBC Server. They hold configuration information, are
involved in name mapping, and are used to support client-visible SQL catalogs.
It is useful to think of the NonStop ODBC Server catalogs as extensions of NonStop
SQL/MP catalogs. A NonStop ODBC Server catalog can exist only on a subvolume
that contains a NonStop SQL/MP catalog (recall that in this case NonStop SQL/MP
objects appear to clients as a database). When asked to create a database, NOSUTIL
creates a SQL/MP catalog if one doesn’t exist in the same subvolume.
There are two types of NonStop ODBC Server catalogs: the NonStop ODBC Server
system catalog and a NonStop ODBC Server user catalog. There must be at least one
NonStop ODBC system catalog on a system for the NonStop ODBC system to