What is the missing privilege when receiving ORA-01031: insufficient privileges when switching container?

You need to grant the SET CONTAINER system privilege to a common user, in order for the user to be able to switch container.

Eksample: you have a common user used for auditing, C##AUDITADMIN:

CREATE USER c##auditadmin IDENTIFIED BY  CONTAINER=ALL;
GRANT AUDIT_ADMIN TO c##auditadmin CONTAINER=ALL;
GRANT SELECT ANY TABLE TO c##auditadmin CONTAINER=ALL;
GRANT CREATE SESSION TO c##auditadmin CONTAINER=ALL;

You log in with your user to the root container:

sqlplus c##auditadmin@cdb
Enter password:

Connected to:
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.16.0.0.0

C##AUDITADMIN@cdb SQL> alter session set container=pdb1;
ERROR:
ORA-01031: insufficient privileges

To grant the required privilege, login as sysdba:

sqlplus / as sysdba

Connected to:
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.16.0.0.0

Grant the SET CONTAINER privilege:

SYS@cdb SQL> grant set container to c##auditadmin container=all;

Grant succeeded.

Connect with C##AUDITADMIN again, and switch to the PDB1 container within your session:

sqlplus c##auditadmin@cdb

Connected to:
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.16.0.0.0

C##AUDITADMIN@cdb SQL> show con_name

CON_NAME
------------------------------
CDB$ROOT
C##AUDITADMIN@cdb SQL> alter session set container=pdb1;

Session altered.

C##AUDITADMIN@cdb SQL> show con_name

CON_NAME
------------------------------
PDB1

Rename table in postgreSQL: syntax

Rename a table:

alter table myschema.mytable rename to mytable_old;

Change ownership for a table:

alter table myschema.mytable owner to anotherschema;

How to generate insert statements for a table in PostgreSQL

Thanks to Carlos Becker for pointing out the following solution on how to generate insert statments for a table in PostgreSQL

pg_dump mydb -n 'myschema' -a -Fp  -t myschema.mytable --column-inserts > /data1/insert_statements.sql| gzip

How to find the oid for a table in PostgreSQL

Connected to the relevant database using the connection tool of your choice, execute the following to find the oid for a table:

mydb # select 'myschema.mytable'::regclass::oid;
   oid
----------
 19561436
(1 row)

Query to find schema size in PostgreSQL

SELECT pg_size_pretty(sum(pg_relation_size(quote_ident(schemaname) || '.' || quote_ident(tablename)))::bigint) FROM pg_tables 
WHERE schemaname = 'yourschema';

Does PostgreSQL support global indexes on partitioned tables?

PostgreSQL does not support Global Indexes, i.e indexes that spans all partitions in a partitioned table. The documentation states:

Although all partitions must have the same columns as their partitioned parent, partitions may have their own indexes, constraints and default values, distinct from those of other partitions.

and

Create an index on the key column(s), as well as any other indexes you might want, on the partitioned table. ... This automatically creates a matching index on each partition, and any partitions you create or attach later will also have such an index. An index or unique constraint declared on a partitioned table is “virtual” in the same way that the partitioned table is: the actual data is in child indexes on the individual partition tables. A proposal to add such feature seem to have been suggested back in 2019, but currently no implementation exists.

I also found this comparison between Oracle and PostgreSQL that elaborates on the topic a bit more.

How to extract hostname withouth FQDN in a shell variable

Taken from https://stackoverflow.com/questions/36151206/hostname-variable-in-shell-script-not-fqdn and really useful:

export HOST=${HOSTNAME%%.*}