A special way of migration 2005-09-28 - By Mark Bole
I started a reply on this same point, then cancelled it, but since you
(Michael McMullen) brought it up, I will add that the whole quoted
paragraph below about "consistent=y" is a jumble of misinformation.
I suggest that over-use of sarcasm intermingled with technical
information is resulting in less signal and more noise.
Exp/imp is the only way to perform a logical backup, and as such has its
legimate uses, and should not be dismissed out-of-hand. Data pump in
version 10g addresses some of the limitations of exp/imp that previously
could only be addressed at the OS level (such as using pipefiles in Unix).
Strong arguments have been made that the growth of undo space should
never be used as an excuse to break up a single business transaction.
Make it as large as it needs to be to handle your longest-running
transaction. Whether that is a consistent export or something else is
not relevant.
-Mark Bole
Michael McMullen wrote:
> quote
> "The whole export will be read into undo segments."
>
> Were you joking on this?
>
Mladen Gogala wrote:
> On 09/28/2005 03:24:39 AM, Andre van Winssen wrote:
>
[...]
>
> There is, of course, one minor detail here: "consistent=y" will make the whole
> export "repeatable" and that means "set transaction read only" as the 1st
statement.
> The whole export will be read into undo segments, providing the rapture
beyond anything
> that words can describe to the people trying to perform transactions amd the
DBA who will
> have to size the UNDO tablespace appropriately. That is how read consistency
is ensured and
> that is especially good for the full export of multi-TB databases.
>
[...]
>
> Of course, the best thing to do with exp/imp is not to perform them at all.
> Replication goes a long way. Someone here was explaining to me what Oracle
Streams
> can do. I bought Madhu Thumma's "Oracle Streams" book (Rampant) and I must
say it's
> an excellent book. Now if only my boss will go for that.
>
>
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