What are the ramifications of having a full or almost nearly full SYSAUX
tablespace (Oracle 19c)?
There are plenty of sites discussing how to view the SYSAUX
occupants, to reduce the size of SYSAUX
via dbms_stat.purge_stats()
, to add datafiles to SYSAUX
tablespace, and to alter_stats_history_retention
to avoid the problem in the future. This is not what is being asked here.
What are the consequences of not doing any of the previously mentioned tasks, but still utilizing the database? I've read that SYSAUX
is important, but not critical (critical stuff is in SYSTEM
). However, I have not seen any further discussion about what are the consequences of continuing to operate with a full SYSAUX
.
For example, will performance be an issue? If so, in what ways?
Does Oracle stop writing to SYSAUX
or does Oracle try to delete just enough "old" items to make room for "new" items? (most likely it depends on what it is, but don't see any documentation or article that describes the resulting behavior of a full SYSAUX
tablespace and what the resulting consequences may be and what to watch out for).
If one gathers stats will Oracle purge the oldest historical stats to make room for the new ones? If so, is it true MMON
gets called to do this "on-the-fly" rather than during the nightly process to maintain the retention setting. If so, is this costly if an application is doing a lot of stat gathering and to what extent is it costly?
Thanks in advance.
EDIT: Please assume that AUDSYS schema is not in SYSAUX tablespace.
Best Answer
The answer to a post mentioned on the side bar guided me to the following.
In
The Oracle® Database
Database Administrator’s Guide
21c
F31835-05
February 2021
in the chapter 11.12 Managing the SYSAUX Tablespace one can read
The view
V$SYSAUX_OCCUPANTS
lists the occupants of the SYSAUX tablespace. In a 12.1 database I found the followingOn a test database you can set the SYSAUX tablespace to read only on a test database and see what happens.
Oracle Support Note "How To Recreate the SYSAUX Tablespace (Doc ID 468116.1)" says