12c Upgrade and Concurrent Stats Gathering

I was upgrading an Exadata test database from 11.2.0.4 to 12.1.0.2 and I came across a failure scenario I had not encountered before. I’ve upgraded a few databases to both 12.1.0.1 and 12.1.0.2 for test purposes, but this was the first one I’d done on Exadata. And the first time I’d encountered such a failure.

I started the upgrade after checking with the pre upgrade script that everything was ready to upgrade. And I ran with the maximum amount of parellelism:

$ORACLE_HOME/perl/bin/perl catctl.pl -n 8 catupgrd.sql
.
.
.
Serial Phase #:81 Files: 1 A process terminated prior to completion.

Died at catcon.pm line 5084.

That was both annoying and surprising. The line in catcon.pm is of no assistance:

   5080   sub catcon_HandleSigchld () {
   5081     print CATCONOUT "A process terminated prior to completion.\n";
   5082     print CATCONOUT "Review the ${catcon_LogFilePathBase}*.log files to identify the failure.\n";
   5083     $SIG{CHLD} = 'IGNORE';  # now ignore any child processes
   5084     die;
   5085   }

But what of more use was the bottom of a catupgrd.log file:

11:12:35 269  /
catrequtlmg: b_StatEvt     = TRUE
catrequtlmg: b_SelProps    = FALSE
catrequtlmg: b_UpgradeMode = TRUE
catrequtlmg: b_InUtlMig    = TRUE
catrequtlmg: Deleting table stats
catrequtlmg: Gathering Table Stats OBJ$MIG
declare
*
ERROR at line 1:
ORA-20000: Unable to gather statistics concurrently: Resource Manager is not
enabled.
ORA-06512: at "SYS.DBMS_STATS", line 34567
ORA-06512: at line 152

This error is coming from the catrequtlmg.sql, but my first thought was checking if the parameter resource_manager_plan was set, and it turned out it wasn’t. However setting the default_plan and running this piece of sql by itself produced the same error:

SQL> @catrequtlmg.sql

PL/SQL procedure successfully completed.

catrequtlmg: b_StatEvt	   = TRUE
catrequtlmg: b_SelProps    = FALSE
catrequtlmg: b_UpgradeMode = TRUE
catrequtlmg: b_InUtlMig    = TRUE
catrequtlmg: Deleting table stats
catrequtlmg: Gathering Table Stats OBJ$MIG
declare
*
ERROR at line 1:
ORA-20000: Unable to gather statistics concurrently: Resource Manager is not
enabled.
ORA-06512: at "SYS.DBMS_STATS", line 34567
ORA-06512: at line 152



PL/SQL procedure successfully completed.

I then started thinking about what it meant by gather statistics concurrently and I noticed that I had indeed set this database to gather stats concurrently (it’s off by default):

SQL> select dbms_stats.get_prefs('concurrent') from dual;

DBMS_STATS.GET_PREFS('CONCURRENT')
--------------------------------------------------------------------------------
TRUE

I then proceeded to turn of this concurrent gathering and rerun the failing SQL:

SQL> exec dbms_stats.set_global_prefs('CONCURRENT','FALSE');

PL/SQL procedure successfully completed.

SQL> select dbms_stats.get_prefs('concurrent') from dual;

DBMS_STATS.GET_PREFS('CONCURRENT')
--------------------------------------------------------------------------------
FALSE


SQL> @catrequtlmg.sql

PL/SQL procedure successfully completed.

catrequtlmg: b_StatEvt	   = TRUE
catrequtlmg: b_SelProps    = FALSE
catrequtlmg: b_UpgradeMode = TRUE
catrequtlmg: b_InUtlMig    = TRUE
catrequtlmg: Deleting table stats
catrequtlmg: Gathering Table Stats OBJ$MIG
catrequtlmg: Gathering Table Stats USER$MIG
catrequtlmg: Gathering Table Stats COL$MIG
catrequtlmg: Gathering Table Stats CLU$MIG
catrequtlmg: Gathering Table Stats CON$MIG
catrequtlmg: Gathering Table Stats TAB$MIG
catrequtlmg: Gathering Table Stats IND$MIG
catrequtlmg: Gathering Table Stats ICOL$MIG
catrequtlmg: Gathering Table Stats LOB$MIG
catrequtlmg: Gathering Table Stats COLTYPE$MIG
catrequtlmg: Gathering Table Stats SUBCOLTYPE$MIG
catrequtlmg: Gathering Table Stats NTAB$MIG
catrequtlmg: Gathering Table Stats REFCON$MIG
catrequtlmg: Gathering Table Stats OPQTYPE$MIG
catrequtlmg: Gathering Table Stats ICOLDEP$MIG
catrequtlmg: Gathering Table Stats TSQ$MIG
catrequtlmg: Gathering Table Stats VIEWTRCOL$MIG
catrequtlmg: Gathering Table Stats ATTRCOL$MIG
catrequtlmg: Gathering Table Stats TYPE_MISC$MIG
catrequtlmg: Gathering Table Stats LIBRARY$MIG
catrequtlmg: Gathering Table Stats ASSEMBLY$MIG
catrequtlmg: delete_props_data: No Props Data

PL/SQL procedure successfully completed.


PL/SQL procedure successfully completed.

It worked! I was able to upgrade my database in the end.

I wish the preupgrade.sql script would check for this. Or indeed when upgrading, the catrequtlmg.sql would disable the concurrent gathering.

I would advise checking for this before any upgrade to 12c and turning it off if you find it in one of your about to be upgraded databases.