If the metadata export takes most of the time, you can do the export in
advance, ensure that no schema (and other metadata) changes happen after
you've started your metadata export and later on load the data separately.
You'd need to worry about metadata that changes implicitly with your
application workload - like sequence numbers increasing. The sequences can
be altered just before switchover to continue from where they left off in
the source.
You can even copy historical partitions (that don't change) over way before
the final migration to cut down the time further. But if XTTS speed is
enough for you for bulk data transfer, then no need to complicate the
process.
Years (and decades) ago, when there was no XTTS and even no RMAN, this is
how you performed large migrations. Copy everything you can over in advance
and only move/refresh what you absolutely need to during the downtime.
--
Tanel Poder
https://tanelpoder.com/seminar
On Sat, Feb 8, 2020 at 10:38 AM Ahmed Fikri <gherrami@xxxxxxxxx> wrote:
Hello Jonathan,
sorry for the confusion.
the productive db is about 16 TB (11.2.0.4 on AIX) and has about 4,5 Mio
Partitions and every day come about 1000 partitions. And the metadata
export takes 3 days 4 hours. The DBA I think is very experienced he had
already find out that the export is slow because of known bug in 11.2.0.4
(he sent me the MOS ID and has mentioned that the problem is related to an
x$k... view - Monday I will send the exact information). Unfortunately I
haven't shown much interest to this information (big mistake) because I
thought that the problem is because of our application design (and this is
only my opinion as developer ) and also I thought that it should be
possible somehow to convert the whole db without the need to use the
datapump for the metadata (from the theory I think it is possible - but as
I realized now it is in the practice tough )
And to check my assumption that we can convert all db datafiles (the
datafiles for the metadata too) using c or c++ I use a 10GB big DB.
Thanks and regards
Ahmed
