ODBC Server Reference Manual

Architecture Overview
HP NonStop ODBC Server Reference Manual—429151-002
2-27
NonStop ODBC Server
ODBC Catalogs
Unlike database vendors, ODBC does not define a SQL catalog schema. Instead, the
ODBC CLI defines functions intended to extract catalog information.
The ODBC functions cover tables, columns, index columns, stored procedures, and
stored procedure columns (the parameters of the procedures). Each CLI function has
parameters that serve to qualify on object names. For example, the function for tables
(called SQLTables) has parameters to qualify on each of the three parts of the name
and the table type.
The NonStop ODBC Server supports these calls for ODBC by having the NonStop
ODBC/MP driver issue corresponding SQL statements against the NonStop SQL/MP
and NonStop ODBC Server catalog tables.
For example, an ODBC application issues a function call of the form:
SQLTables (tablename = "XY*")
The NonStop ODBC/MP driver forms a query of the following generalized form and
sends it to the NonStop ODBC Server:
select ...
from ZVUOBJ
where name like "XY%"
The NonStop ODBC server processes the SELECT statement in the normal manner.
An additional table (ZVUOCOL) was added to the NonStop ODBC Server catalog
tables needed for TSQL support to enable the NonStop ODBC Server to support
ODBC catalog functions.
NonStop ODBC Server
The NonStop ODBC server is the physical server process within the NonStop ODBC
Server product. The principal task of the NonStop ODBC server is to deal with SQL
statements from clients. This is similar to NonStop SQL/MP’s task of compiling and
executing NonStop SQL/MP statements. Each NonStop ODBC server is dedicated to
one client connection at a time. When not servicing a client, SCS maintains idle
NonStop ODBC servers in a free pool.
The life cycle of an NonStop ODBC server process is shown in Figure 2-22.