SQL/MP Programming Manual for COBOL

Explicit Program Compilation
HP NonStop SQL/MP Programming Manual for COBOL—529758-003
6-43
Using CONTROL Directives
FILE guardian-name
... ...
In the next example, the SQL compiler writes an execution plan and DEFINEs to the
spooler location $S.#EXPLAIN. The OBEYFORM option directs the compiler to write
the DEFINEs in OBEY command file format to the file named SETDEFS for
subsequent execution. The catalog name is not included in the SQLCOMP command
because it is stored in the program file. The NOOBJECT option suppresses the
generation of a new object file, so the SQL compiler does not register the program file
in a catalog.
SQLCOMP /IN SQLPROG,OUT $S.#EXPLAIN/ NOOBJECT,
EXPLAIN PLAN DEFINES SETDEFS, OBEYFORM
For more information about the EXPLAIN utility, including detailed examples and
reports, see the SQL/MP Query Guide.
Using CONTROL Directives
You can use these CONTROL directives with either static or dynamic SQL statements
in a COBOL program:
CONTROL EXECUTOR
allows or prohibits parallel execution of a query by multiple SQL executors. Parallel
execution can decrease the elapsed time for processing a query.
CONTROL QUERY
controls query execution plans as follows:

Optimization of query response time for returning only the first few rows found
or for returning all rows found

Use of hash join algorithms in execution plans

Use of execution-time name resolution to resolve names in execution plans
when the SQL statement executes rather than during explicit SQL compilation
or at SQL load time
CONTROL TABLE
controls these performance-related options for accessing tables and views:

Selection of access paths, join methods, join sequences, and lock types

Selection of block buffering and block splitting algorithms

Action to take for locked data or unavailable partitions

Opening of indexes and partitions at the initial access to a table

Checkpointing of unaudited write operations
The use of CONTROL directives in a COBOL program is discussed next. For the
syntax of each CONTROL directive, see the SQL/MP Reference Manual.