There usually a philosophic battle happening when it comes to underscore parameters. The official statement is more or less: It’s an underscore, hence it is undocumented and you shouldn’t touch it unless Oracle Support advises you to do so. I agree in many cases. But in this specific one, I don’t. And in this post I will explain why you should set _EXCLUDE_SEED_CDB_VIEW=FALSE in all your singe- and Multitenant environments. Always!

A bit of history

At first, a little bit of a history excursion. This parameter wasn’t an underscore in Oracle 12.1. You can find it as EXCLUDE_SEED_CDB_VIEW in …

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How to patch all PDBs with the a new time zone file?

Yesterday I wrote about how to adjust the time zone setting in the PDB$SEED as by default the time zone scripts won’t touch the PDB$SEED when you execute them. And in addition, MOS Note:1509653.1 tells you, that the PDB$SEED can’t be adjusted. But this leads to a weird mix of time zone settings across a Multitenant deployment. Which I’d guess is not desired. Following a tweet reply by Marco Mischke I realized: I explained how to patch the PDB$SEED – but I didn’t explain how to patch all PDBs with the a new time zone file?

How to patch all PDBs with the a new time zone file?

Photo by Laureen

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How to speed up Multitenant CUSTOM database creation

Why has the PDB$SEED such a strange setup?I usually create my container databases for testing with the CUSTOM option of DBCA. That allows me to specify exactly the components I’d like to have – or not. But I realized two things during the CUSTOM creation: It takes very long. And in the alert.log I see resize operations especially with the PDB$SEED during dictionary view creation. I see heap warnings. And recompilations. I did ask myself how to speed up Multitenant CUSTOM database creation.

Background Information

The PDB$SEED is the – I call it – “blueprint” pluggable database. It’s sole purpose is to allow you fast provisioning of …

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Why EXCLUDE_SEED_CDB_VIEW is now an underscore in Oracle 12.2

Hiding information is not good - and exclude_seed_cdb_view is now an underscore in Oracle 12.2I 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 To be fair, the exclude_seed_cdb_view is listed in the list of obsolete parameters in Oracle Database


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 …

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Why does the upgrade of PDB$SEED always take longer?

Upgrading the PDB$SEED takes always longer than any other container.
What is the reason for an upgrade of the PDB$SEED taking so much longer in a real world environment?

How does an upgrade with Oracle Multitenant work?

Upgrading the PDB$SEED takes always longerI have written several blog posts in the past about the different techniques to upgrade an Oracle Multitenant environment:

  1. Upgrade Everything At Once
  2. Upgrade via Unplug/Plug/Upgrade

The interesting case happens in the “Everything At Once“. The PDB$SEED takes significantly longer to upgrade than any other container.

Upgrading the PDB$SEED takes always longer?

Quick recap: The PDB$SEED is the (I call it) blueprint

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