Perhaps you have enabled the trace in a certain session, analyzed (and
removed) the tracefile and disabled the event.
If you then, later on re-enable the trace for the same session, no trace
file will be written.
The reason is, that Oracle keeps the file descriptor open, pointing to the
"old" file still, which isn't there anymore. No new file will be created.
A workaround is, BEFORE you enable your event, figure out the name of the
tracefile that will be written to (ORacle uses uniform formats, can easily
be predicted) , and put a named pipe in its place. Then, when you enable the
trace, you start reading from that pipe (using i.e. tail -f ), and write
that output to a file you want to analyze. Using this technique, you can
easily enable and disable the trace, and it'll work just fine, as long as
the named pipe stays in place.
Stefan
