IBM Tivoli NetView for z/OS Programming: Pipes - IBM notice

* Drop a table */
’pipe lit /drop table jtest/| SQL execute|console’
Using Multiple Concurrent SQL Stages
Up to 10 SQL stages can run concurrently in all active pipelines. Use the
NOCOMMIT option in concurrent operations. DB2 considers all SQL stages to be
part of one unit of work; an implied commit by a stage causes errors when other
stages resume. Explicit commit or rollback is done with SQL COMMIT and SQL
ROLLBACK.
/* Merge two tables */
’PIPE (end ?)’,
’SQL nocommit noclose select * from
table1 |SEP| p: FANIN | CONS ?’,
’SQL nocommit select * from table2 |SEP| p:’
’PIPE SQL execute commit work’
PIPE SQL
Use NOCLOSE to leave the plan open from one pipe to another on the same
NetView task. The plan closes when all concurrent SQL stages have terminated. A
NOCLOSE option used in any (concurrent) stage of a pipe makes the plan stay
open when the pipe ends.
When accessing multiple DB2 subsystems from a NetView system, you cannot
directly access multiple DB2 subsystems on a single task without having the SQL
close and reopen the plan. Consider using multiple autotasks which interfaces with
a different DB2 subsystem as servers for other tasks. You can use labeled
commands and pipes to correlate the SQL requests running on the separate tasks.
The plan closes when none of the SQL stages within the pipe specify NOCLOSE.
For example, PIPE SQL COMMIT WORK | CONSOLE commits the unit of work and close
the active plan.
Note: If a plan is left open and the REXX procedure ends, the plan remains open
until a subsequent pipe closes it or the task ends. A REXX procedure might
use PIPE SQL COMMIT WORK | CONS at the start of SQL processing to ensure
that any previous plan is closed. Alternatively, use PIPE SQL NOCLOSE
CONNECT RESET | CONS to ensure that the local database is being used and
the plan is open.
Use NOCLOSE:
v When using SQL CONNECT to a remote database, a NOCLOSE enables you to
keep the remote connection between two pipes. You might find it convenient to
open a remote connection in one pipe, do some processing in REXX, and then
finish working with the remote connection in a second pipe. You specify
NOCLOSE in the first pipe and omit the operand in the second pipe.
v When using database locks in SQL, use NOCLOSE to keep the locks from one
PIPE to the next.
v When using applications requiring two pipes to implement one function,
typically, with other (REXX) processing between the two pipes.
Other Considerations When Using SQL
When using SQL, consider that:
v DB2 statements are read from the primary input stream when EXECUTE is used.
The query results are written to the primary output stream. Error and diagnostic
messages are written to the secondary output stream.
v SQL terminates when the primary output stream is disconnected. It also
terminates if a negative return code is received from DB2.
Chapter 2. Pipeline Stages and Syntax 223