SQL Programming Manual for Pascal

Program Compilation and Execution
HP NonStop SQL Programming Manual for Pascal—528614-001
5-28
Maximizing Local Autonomy
•
If the SQL executor subsequently tries to execute the uncompiled statement, the
SQL executor tries again to automatically recompile the statement. If the statement
still causes a compilation error or warning, the SQL executor returns a run-time
error message to the program.
At run time, a program receives SQL compiler errors only when the SQL statement that
produces the error executes.
Maximizing Local Autonomy
Local autonomy in a network-distributed database ensures that a program can access
data on the local system, regardless of the availability of remote SQL objects. If your
program accesses a network-distributed database, you can maximize local autonomy
by:
•
Using a local partition, rather than the primary partition, as the table name for
partitioned tables
•
Using DEFINEs
•
Using current statistics
•
Skipping unavailable partitions
For more information about managing applications for local autonomy, see the
NonStop SQL Installation and Management Manual.
Using a Local Partition
If your program uses a remote partition, the SQL compiler looks for information about
the table in a remote catalog. If the remote system is down, the SQL compilation fails;
however, if your program uses a local partition, the SQL compiler looks for the
information in a local catalog. Provided the local system and the data is available, the
SQL compilation is successful.
The following example shows the concept of maximizing local autonomy. The PARTS
table is a partitioned table that resides on the \NEWYORK and \CHICAGO systems:
A program declares a cursor defined as:
EXEC SQL DECLARE GET_PART_CURSOR CURSOR FOR
SELECT PARTNUM, PARTDESC, PRICE, QTY_AVAILABLE
FROM =PARTS
WHERE PARTS.PARTNUM < 5000
AND PARTS.PARTDESC = "V8 DISK OPTION";
\NEWYORK The first partition contains all rows in which PARTS.PARTNUM (the primary
key) is less than 5000.
\CHICAGO The second partition contains all rows in which PARTS.PARTNUM is 5000 or
greater. An index on the PARTDESC column of table PARTS is named
IXPART.