Oracle DBA Lesson 5B — Working in the Right Container

Oracle DBA · Lesson 5B

Working in the Right Container

Your session is always in one container. Confirm it with SHOW CON_NAME before you create users or objects — then switch if you are in the wrong place.

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Oracle DBA Lesson 5B — Working in the Right Container

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Session context is the habit

Lesson 5A named the pieces: root, seed, and user PDBs. This lesson is the daily practice — before you create a local user, a tablespace, or an object, you name the container you are in.

A session lives in one container at a time. Guessing from the connection string is not enough. Confirm it.

Confirm with SHOW CON_NAME

SHOW CON_NAME prints the current container for this session. Make it the first check after connect, and again after any switch.

SHOW CON_NAME

Returns the container this session is in right now — for example CDB$ROOT, SALES, or HR.

Wrong container, wrong object

Suppose SHOW CON_NAME returns SALES, and the next ticket is “create an HR local user.” SALES is the wrong place. Creating the user there either fails the intent or leaves an account the HR app cannot use as a local PDB user.

Move to the required target first. Do the work second.

Switch with ALTER SESSION SET CONTAINER

From a privileged session that can see other containers, switch in place:

ALTER SESSION SET CONTAINER = hr;
SHOW CON_NAME;

Moves this session into the HR PDB, then confirms the name. Replace hr with your PDB name.

Or connect to the PDB service

Another clean path: connect with a service that lands you in the PDB you need. Then confirm again with SHOW CON_NAME. Either route is fine — the rule is the same: prove the container before DDL.

-- After connect to the HR service:
SHOW CON_NAME;
-- Expect: HR (or your PDB name)

Root vs PDB work

Some tasks belong in CDB$ROOT (startup, common users, CDB-wide views). Application local users and app tablespaces belong in the application PDB. Match the task to the container — then confirm you are actually there.

Gotchas

• Do not create an HR local user while your session is still in SALES (or root).
• A connection identifier is a hint, not proof — always SHOW CON_NAME.
• After ALTER SESSION SET CONTAINER, confirm again before DDL.
• Put the container name in the ticket or change note so the next person is not guessing.

Quick quiz

Choose one answer per question, then submit. You’ll see the correct answer and a short why.

1. SHOW CON_NAME returns SALES. Next task: create an HR local user. Is SALES the correct container?

Yes — any open PDB is fine for local users No — switch to HR first, then create the user Yes — local users always go in SALES Only if PDB$SEED is closed

2. What does SHOW CON_NAME tell you?

Which container this session is in right now Every PDB on the listener The last container you ever used on this host Whether redo is archived

3. You are in CDB$ROOT and need to work in the HR PDB in this same session. What do you run?

ALTER DATABASE OPEN HR; CREATE USER hr IDENTIFIED BY … in root ALTER SESSION SET CONTAINER = hr; then SHOW CON_NAME DROP PDB hr INCLUDING DATAFILES

4. Where should an application’s local user and tablespace live?

Only in CDB$ROOT Only in PDB$SEED In every PDB at once with one CREATE USER In that application’s PDB

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