In a previous blog post I wrote about the importance of gathering fixed objects statistics at the right time.

I argued that you could create a scheduler job that re-gathers fixed objects statistics after a number of days (and the database is warmed-up). If you like that idea here is how you can implement that in AutoUpgrade.

Schedule Fixed Objects Statistics Gathering

CDB

First, create a file named /home/oracle/sched_gfos/sched_gfos.sql:

BEGIN
   DBMS_SCHEDULER.CREATE_JOB (
      job_name => '"SYS"."GATHER_FIXED_OBJECTS_STATS_ONE_TIME"',
	  job_type => 'PLSQL_BLOCK',
	  job_action => 'BEGIN DBMS_STATS.GATHER_FIXED_OBJECTS_STATS; END;',
	  start_date => SYSDATE+7,
	  auto_drop => TRUE,
	  comments => 'Gather fixed objects stats after upgrade - one time'   
   );
   DBMS_SCHEDULER.ENABLE (
      name => '"SYS"."GATHER_FIXED_OBJECTS_STATS_ONE_TIME"'
   );
END;
/

Next, create a script named /home/oracle/sched_gfos/sched_gfos.sh. It will run the SQL script in all PDBs including CDB$ROOT, except PDB$SEED. I don’t want to run in PDB$SEED because it is normally in READ ONLY state:

export ORACLE_SID=CDB1
export ORACLE_HOME=/u01/app/oracle/product/19
export PATH=$ORACLE_HOME/bin:$PATH
$ORACLE_HOME/perl/bin/perl $ORACLE_HOME/rdbms/admin/catcon.pl -n 4 -C 'PDB$SEED' -e -b sched_gfos -d /home/oracle/sched_gfos/ sched_gfos.sql

And then I add the following line to my config file:

upg1.after_action=/home/oracle/sched_gfos/sched_gfos.sh

Non-CDB

First, create a file named /home/oracle/sched_gfos/sched_gfos.sql:

BEGIN
   DBMS_SCHEDULER.CREATE_JOB (
      job_name => '"SYS"."GATHER_FIXED_OBJECTS_STATS_ONE_TIME"',
	  job_type => 'PLSQL_BLOCK',
	  job_action => 'BEGIN DBMS_STATS.GATHER_FIXED_OBJECTS_STATS; END;',
	  start_date => SYSDATE+7,
	  auto_drop => TRUE,
	  comments => 'Gather fixed objects stats after upgrade - one time'   
   );
   DBMS_SCHEDULER.ENABLE (
      name => '"SYS"."GATHER_FIXED_OBJECTS_STATS_ONE_TIME"'
   );
END;
/
EXIT

Next, create a script named /home/oracle/sched_gfos/sched_gfos.sh:

export ORACLE_SID=DB1
export ORACLE_HOME=/u01/app/oracle/product/19
export PATH=$ORACLE_HOME/bin:$PATH
sqlplus / as sysdba @/home/oracle/sched_gfos/sched_gfos.sql

And then I add the following line to my config file:

upg1.after_action=/home/oracle/sched_gfos/sched_gfos.sh

Appendix

A previous version of AutoUpgrade gathered fixed objects stats immediately after upgrade. This was not in line with our own recommendations. This has been fixed in AutoUpgrade 19.9.2. Thanks to a keen reader of the blog, Robert Ortel, who made a comment on this.

For reference, here is the workaround I shared to fix the wrong behaviour.

Prevent AutoUpgrade From Gathering Fixed Objects Statistics

AutoUpgrade is by design very flexible and there is a way to override the default fixups. It is very well described in our documentation and Mike Dietrich has a really good blog post about it.

The fixup that you want to override and disable is:

[checkname]          POST_FIXED_OBJECTS
[stage]              POSTCHECKS
[fixup_available]    YES
[runfix]             YES <== Change to NO 
[severity]           RECOMMEND

And you should change runfix to NO. Save the checklist file and reference it from the AutoUpgrade config file using the checklist parameter.