I was asked to refresh one of the development PDB tenants from the
corresponding production PDB. The platform is Linux x86_64 (OL 7.7) with
Oracle 19.10 (Jan 2021 RU). Unfortunately, due to security measures,
the only open port between the production server and the development
server is 22. That eliminates remote clone. The tenant size in
production is around 1TB. I opted for unplug pluggable database into
'/tmp/tenant.pdb'. That took almost 2 hours with very fast disk storage
(Pure array) and a powerful CPU. It was single threaded. Is there any
way I can use multiple threads? The .pdb archive is compressed and my
bottleneck was it being run on a single CPU. Is there any trick to do
that with RMAN? The production has 144 cores and I could easily afford
running 12 threads at a time. Unfortunately, I can't restore pluggable
database into another CDB using rman. This was like pulling teeth. I
couldn't get SQL*Net port (it isn't 1521) open so I had to unplug.
Fortunately, I knew what was I in for so I first did unplug to XML,
dropped the pluggable database with "keep datafiles" and plugged it back
in using XML. The whole thing is extremely awkward. The funny thing was
that "CREATE PLUGGABLE DATABASE TESTDB3 USING '/tmp/tenant.pdb'" used 2
cores. It was 4 times as fast as creating the PDB archive. Oracle's
multi-tenant leaves a lot to be improved. I hope that Oracle 21 might
address some of these issues.
--
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
https://dbwhisperer.wordpress.com
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