I/O Tracing
SET IO_TRACE prints out information about disk I/O during the life of each query.
The following command turns I/O trace on as the default ING_SET level:
Windows:
SET ING_SET=set io_trace
UNIX:
C Shell:
setenv ING_SET "set io_trace"
Bourne Shell:
ING_SET = "set io_trace"
export ING_SET
VMS:
DEFINE ING_SET "SET IO_TRACE"
For example, given the query:
select * from iirelation;
Here is a sample output from the I/O trace. The counts are the number of pages read/written:
***************************************************************
I/O READ File: aaaaaaac.t00 (iidbdb, iirel_idx, 13) count:1
***************************************************************
***************************************************************
I/O READ File: aaaaaaab.t00 (iidbdb, iirelation, 0) count:8
***************************************************************
***************************************************************
I/O READ File: aaaaaaab.t00 (iidbdb, iirelation, 8) count:8
***************************************************************
I/O READ File: aaaaaaab.t00 (iidbdb, iirelation, 16) count:7
Note: When tracing the I/O or the locks of a parallel query (using SET IO_TRACE or SET LOCK_TRACE with SET PARALLEL n), the trace messages from child threads of the QEP are logged to the II_DBMS_LOG. The trace messages for the main thread are sent to the user session in the normal manner.
Lock Tracing
SET LOCK_TRACE prints out information about locks within a transaction.
The following command turns lock tracing on as the default ING_SET level:
Windows:
set ING_SET=set lock_trace
UNIX:
C Shell:
setenv ING_SET "set lock_trace"
Bourne Shell:
ING_SET = "set lock_trace"export ING_SET
VMS:
DEFINE ING_SET "SET LOCK_TRACE"
Event Tracing
The following features enable your application to display and trace events:
• To enable or disable the display of events when they are raised by the application, use the following command:
SET [NO]PRINTDBEVENTS
• To enable or disable the logging of events to the installation log file as they are raised by the application, use the following statement:
SET [NO]LOGDBEVENTS
• To enable or disable the display of events as they are received by an application, use the following statement:
SET_SQL(DBEVENTDISPLAY = 1 | 0)
Specify a value of 1 to enable the display of received events, or 0 to disable the display of received events. You can also enable this feature using II_EMBED_SET.
You can create a routine that traps all events returned to an embedded SQL application. To enable/disable an event-handling routine or function, your embedded SQL application must issue the following SET_SQL statement:
EXEC SQL SET_SQL(DBEVENTHANDLER = event_routine | 0)
To trap events to your event-handling routine, specify event_routine as a pointer to your error-handling function. For information about specifying pointers to functions, see your host language companion guide. In addition to issuing the SET_SQL statement, you must create the event-handling routine, declare it, and link it with your application.
Last modified date: 01/30/2023