Why EXCLUDE_SEED_CDB_VIEW is now an underscore in Oracle 12.2

I have received several questions from customers in the past weeks using Oracle Multitenant about the parameter exclude_seed_cdb_view.It magically disappeared and morphed into _exclude_seed_cdb_view since Oracle Database 12.2.0.1. To be fair, the exclude_seed_cdb_view is listed in the list of obsolete parameters in Oracle Database 12.2.0.1.

What is EXCLUDE_SEED_CDB_VIEW?

This parameter hides everything belonging to the PDB$SEED from the usual queries. For instance you ran a query against CDB_DATA_FILES but you won’t see the data files belonging to PDB$SEED in the result set. Whether this is good or bad, at least RMAN (Recovery Manager) worked always correctly.

But I’m not a big fan of “hiding” something. Why do things belonging to the PDB$SEED are hidden? To me that does not make much sense. I’m one of these people always turning off the “hide file extensions” and “hide system files” on Windows boxes.

In this case I don’t know the deeper reason. For Oracle Database 12.1 I recommend to set exclude_seed_cdb_view to FALSE if you are using Oracle Single-/Multitenant.

SQL> alter system set EXCLUDE_SEED_CDB_VIEW=FALSE scope=both;

Just on the side, the parameter was undocumented in Oracle Database 12.1.0.2.

Why is EXCLUDE_SEED_CDB_VIEW now _EXCLUDE_SEED_CDB_VIEW in Oracle 12.2?

Good question – maybe because underscores don’t have to be documented?I have really no idea.

Fact is that the parameter exclude_seed_cdb_view morphed into an underscore parameter _exclude_seed_cdb_view in Oracle Database 12.2.0.1. Though I stay with my recommendation: set it to FALSE:

SQL> alter system set "_EXCLUDE_SEED_CDB_VIEW"=FALSE scope=both;

Why do I set it to FALSE?

I came across several customer examples where it is essential to see everything. Dagmar Förster from a German insurance raised an issue to me. She is checking if all PDBs are patches correctly by the recent datapatch run. But when the seed’s objects get excluded by default you won’t find it out:

select CON_ID,PATCH_ID,VERSION,STATUS,ACTION,DESCRIPTION from cdb_registry_sqlpatch order by action_time;

CON_ID PATCH_ID VERSION  STATUS  ACTION DESCRIPTION
------ -------- -------- ------- ------ ----------------------------------------
     1 26123830 12.2.0.1 SUCCESS APPLY  DATABASE RELEASE UPDATE 12.2.0.1.170718
     3 26123830 12.2.0.1 SUCCESS APPLY  DATABASE RELEASE UPDATE 12.2.0.1.170718
     4 26123830 12.2.0.1 SUCCESS APPLY  DATABASE RELEASE UPDATE 12.2.0.1.170718

Reminds me a lot on Where’s Wally? Obviously you don’t see information about whether the July 2017 RU’s SQL changes have been applied to the PDB$SEED (CON_ID=2) or not. Everything belonging to CON_ID=2 gets hidden.

And this is just one of a number of examples I’ve heard about in the past weeks.

–Mike