Oracle diagnostic events is a great feature, but unfortunately poorly documented and nonintuitive, so it’s difficult to remember all events/actions/parameters and even read its internal documentation using oradebug. So I decided to compile its internal doc as a more convenient html-version (https://orasql.org/files/events/) and make a cheat sheet of some unknown or little-known use cases.
Example 1:
1 2 3 4 5 6 | alter system set events 'kg_event[1476] {occurence: start_after 1, end_after 3} trace("stack is: %\n", shortstack()) errorstack(2) '; |
- kg_event[errno] – Kernel Generic event in library Generic for error number events, which instructs to trace ORA-errno errors;
- {occurence: start_after X, end_after Y} – is a filter, which instructs to skip X event checks and trace just Y times;
- trace(format, str1, str2, …, str15) – is a function from ACTIONS for printing into a trace file;
- shortstack() – is a function from ACTIONS , which returns a short call stack as a string;
- errorstack(level) – is a function from ACTIONS, which prints extended info (level: 0 – errorstack only, 1 – errorstack + call stack, 2 – as level 1 + processtate, 3 – as level 2 + context area). You can get more details with PROCESSSTATE or SYSTEMSTATE. If you need just a call stack, you can use CALLSTACK(level) , with function arguments in case of level>1.
Example 2:
1 2 3 4 5 6 | alter system set events 'trace[SQL_Compiler.* | SQL_Execution.*] [SQL: ...] {process: ospid = ...} {occurence:end_after 3} controlc_signal()'; |