Oracle Wait Event Name vs. Display Name


Here’s a little SQL query that lists all Oracle wait events where Oracle kernel developers have added additional “human readable” descriptions. Since the original wait event names shouldn’t be changed for compatibility with existing tools, then a new column DISPLAY_NAME was added:

SQL> SELECT name, display_name FROM v$event_name WHERE name != display_name;

NAME                                      DISPLAY_NAME
----------------------------------------- ----------------------------------------------------------------
control file sequential read              control file read
control file single write                 control file write
log file sequential read                  log file multiblock read
log file single write                     log file header write
log file parallel write                   log file redo write
log buffer space                          log buffer full - LGWR bottleneck
log file sync                             commit: log file sync
LGWR real time apply sync                 standby apply advance notification
db file sequential read                   db single block read
db file scattered read                    db multiblock read
db file single write                      db single block write
db file parallel write                    db list of blocks write
db file parallel read                     db list of blocks read
wait for possible quiesce finish          quiesce database completion
concurrent I/O completion                 online move datafile IO completion
datafile copy range completion            online move datafile copy range completion
Image redo gen delay                      redo resource management
Long operation CF pause                   CF txn pause
DFS db file lock                          quiesce for datafile offline
datafile move cleanup during resize       online move datafile resize cleanup

From the above highlighted examples you can see that the new “display name” column uses less confusing names for some wait events.

That’s all for today! If you want to learn more about Oracle Wait Interface deep internals (unexpected stuff like wait events renaming themselves on completion, nested multi-level wait events, etc), then check out my hacking session video:

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