PL/SQL Packages and Types Reference 10g Release 1 (10.1) Part Number B10802-01 |
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The DBMS_TRACE
package contains the interface to trace PL/SQL functions, procedures, and exceptions.
This chapter contains the following topics:
DBMS_TRACE
provides subprograms to start and stop PL/SQL tracing in a session. Oracle collects the trace data as the program executes and writes it to database tables.
A typical session involves:
DBMS_TRACE
.SET_PLSQL_TRACE
).DBMS_TRACE
.CLEAR_PLSQL_TRACE
).This package must be created under SYS
.
DBMS_TRACE
uses these constants:
trace_all_calls constant INTEGER := 1; trace_enabled_calls constant INTEGER := 2; trace_all_exceptions constant INTEGER := 4; trace_enabled_exceptions constant INTEGER := 8; trace_all_sql constant INTEGER := 32; trace_enabled_sql constant INTEGER := 64; trace_all_lines constant INTEGER := 128; trace_enabled_lines constant INTEGER := 256; trace_stop constant INTEGER := 16384; trace_pause constant INTEGER := 4096; trace_resume constant INTEGER := 8192; trace_limit constant INTEGER := 16; trace_major_version constant BINARY_INTEGER := 1; trace_minor_version constant BINARY_INTEGER := 0;
Oracle recommends using the symbolic form for all these constants.
You cannot use PL/SQL tracing in a shared server environment.
Profiling large applications may produce a large volume of data. You can control the volume of data collected by enabling specific program units for trace data collection.
You can enable a program unit by compiling it debug. This can be done in one of two ways:
alter session set plsql_debug=true; create or replace ... /* create the library units - debug information will be generated */
or:
/* recompile specific library unit with debug option */ alter [PROCEDURE | FUNCTION | PACKAGE BODY] <libunit-name> compile debug;
You can limit the amount of storage used in the database by retaining only the most recent 8,192 records (approximately) by including TRACE_LIMIT
in the TRACE_LEVEL
parameter of the SET_PLSQL_TRACE
procedure.
You must create database tables into which the DBMS_TRACE package writes output. Otherwise, the data is not collected. To create these tables, run the script TRACETAB.SQL
. The tables this script creates are owned by SYS.
The PL/SQL features you can trace are described in the script DBMSPBT.SQL
. Some of the key tracing features are:
Additional features of DBMS_TRACE also allow pausing and resuming trace, and limiting the output.
Two levels of call tracing are available:
trace_all_calls
.trace_enabled_calls
.Enabling cannot be detected for remote procedure calls (RPCs); hence, RPCs are only traced with level 1.
Two levels of exception tracing are available:
trace_all_exceptions
.trace_enabled_exceptions
.Two levels of SQL tracing are available:
trace_all_sql
.trace_enabled_sql
.Two levels of line tracing are available:
trace_all_lines
.trace_enabled_lines
.When tracing lines, Oracle adds a record to the database each time the line number changes. This includes line number changes due to procedure calls and returns.
Note: For both all types of tracing, level 1 overrides level 2. For example, if both level 1 and level 2 are enabled, then level 1 takes precedence. |
If tracing is requested only for enabled program units, and if the current program unit is not enabled, then no trace data is written.
When tracing calls, both the call and return are traced. The check for whether tracing is "enabled" passes if either the called routine or the calling routine is "enabled".
Call tracing will always output the program unit type, program unit name, and line number for both the caller and the callee. It will output the caller's stack depth. If the caller's unit is enabled, the calling procedure name will also be output. If the callee's unit is enabled, the called procedure name will be output
Exception tracing writes out the line number. Raising the exception shows information on whether the exception is user-defined or pre-defined. It also shows the exception number in the case of pre-defined exceptions. Both the place where the exceptions are raised and their handler is traced. The check for tracing being "enabled" is done independently for the place where the exception is raised and the place where the exception is handled.
All calls to DBMS_TRACE.SET_PLSQL_TRACE
and DBMS_TRACE.CLEAR_PLSQL_TRACE
place a special trace record in the database. Therefore, it is always possible to determine when trace settings were changed.
As well as determining which items are collected, you can pause and resume the trace process. No information is gathered between the time that tracing is paused and the time that it is resumed. The constants TRACE_PAUSE
and TRACE_RESUME
are used to accomplish this. Trace records are generated to indicate that the trace was paused/resumed.
It is also possible to retain only the last 8,192 trace events of a run by using the constant TRACE_LIMIT
. This allows tracing to be turned on without filling up the database. When tracing stops, the last 8,192 records are saved. The limit is approximate, since it is not checked on every trace record. At least the requested number of trace records will be generated; up to 1,000 additional records may be generated.
Subprogram | Description |
---|---|
Stops trace data dumping in session | |
Gets the version number of the trace package | |
Starts tracing in the current session |
This procedure disables trace data collection.
DBMS_TRACE.CLEAR_PLSQL_TRACE;
This procedure gets the version number of the trace package. It returns the major and minor version number of the DBMS_TRACE
package.
DBMS_TRACE.PLSQL_TRACE_VERSION ( major OUT BINARY_INTEGER, minor OUT BINARY_INTEGER);
Parameter | Description |
---|---|
|
Major version number of |
|
Minor version number of |
This procedure enables PL/SQL trace data collection.
DBMS_TRACE.SET_PLSQL_TRACE ( trace_level INTEGER);
Parameter | Description |
---|---|
|
You must supply one or more of the constants as listed. By summing the constants, you can enable tracing of multiple PL/SQL language features simultaneously. The control constants "trace_pause", "trace_resume" and "trace_stop" should not be used in combination with other constants Also see "Collecting Trace Data" for more information. |