Glossary




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Session's response time — this is an interval of time between moment of sending, by the user, request or requests to a DB and obtaining its results. Thus it is possible to consider "response time" as elapsed time between click on the button «Generate report» and the moment when report will displayed on the screen.

Session's resource profile — this is a table, that lists the elements (eg - events), the execution of which is the response time of the session. For example, if session generates a database query, then resource profile will include an events of parse, exec, fetch and reading physical database files waits. This table can also be expanded with additional characteristics: total/max/min/avg elapsed time, number of occurrences for the element. The elements of the session's resource profile are sorted in descending order of contribution to the session's response time. For more information on the principles of building session's resource profiles you can found in the remarkable book “Optimizing Oracle Performance” by Cary Millsap with Jeff Holt.

Trace-file — (extended SQL trace file) this is a file, that contains sequentially written actions of the database's core (execution, fetching, waits etc.), caused by SQL statement execution in some session. For generation of the trace-files, you should set pseudo-event 10046 for the session. You can find more information about trace-file content in the Oracle note ID 39817.1 (http://metalink.oracle.com).

Preamble (of trace-file) — this is trace-file's header, containing description of the session (the original location, OS version, Oracle version, process identifiers).

SQL cursor — this is command of SQL or PL/SQL, executed by user or database core, recorded in section PARSING IN CURSOR, RPC CALL, etc. of the trace-file. Within the trace-file, the cursor may be used repeatedly, ie, opened -> executed-> closed or executed repeatedly without closing.

SQL statement — a more general presentation of SQL cursors, that allows to combine data from multiple cursors with the similar body (different only by literals). For example, cursors for commands SELECT 'TEST' FROM DUAL and SELECT 'WORK' FROM DUAL, will have different IDs, but all difference in them - the use of literals 'WORK' and 'TEST'. If the trace-file will contain many of such cursors, the assessment of the impact on response time, without combining it data will be difficult. By default, the application combines data for cursors with identical body (literals are not analyzed). You can change this approach via options of application or profiler.

Recursive SQL statement — this is SQL statement, has been called by other SQL statement (eg - user's).

Duration (time) — time of the processing event on CPU (c) or waiting time during file read (ela).

Elapsed (time) — overall time of event (e).

Application folder – this is a folder with the installed LightProfiler application. For OS Windows (precompiled version), default installation path is c:\LightProfiler. For OS *nix, default installation path is /usr/local/share/application/lightprofiler.

Profiler — this is integrated tool of application, used for trace-file analyze and report generation (“Resource profile” and “Optimization”).

Tool — this is application on Python language, having TCL/Tk interface (tkinter module), and was written in accordance with specified requirements.

xtrc-file — this is dumped state of parsed profiler, that contain information about the options and the internal data structures. Xtrc-file can be created during export process. In common case, import of xtrc-file can be accomplished faster then parsing of the source trace-file. (Note! We constantly work on reduction time of parsing, so in future releases use of xtrc-files may be discontinued).

sdmp-file — this is file in csv format, that contains information about events for the specified SQL statement. The application will generate this files when using debug-level: Sdmp or All. Below an example of files fragment:

    Sample of sdmp-file
    Pic. 61 Sample of sdmp-file

, was used following notation:

btim – start time of event

etim – end time of event

nam – name of event

estyle – event internal type (see below)

c – duration on CPU (with children)

e — elapsed time (with children)

dur — total duration (with children)

ic – duration on CPU (without children)

ie — elapsed time ( without children)

idur — total duration ( without children)

In the current version used following type of events:

  • 0 - common event (such as CLOSE)

  • 1 - synthetic event, is generated by the application to mark cursor closing

  • 2 - synthetic event, call's delta

  • 10 - database call (PARSE, EXEC, etc.)

  • 11 - event of processing LOB-data

  • 100 - common case of wait event

  • 101 - "internal" wait event, not connected with database file processing

  • 102 - "external" wait event occurring "between" database calls (for example - events from / to client)

  • 103 - wait event associated with database file processing

  • 104 - synthetic wait event generated by the application, with using of experimental options - "process tim markers"


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