Re: Full export and sequence behaviour in 8i
Date: Sun, 15 Mar 2009 22:39:07 +0800
In the first place, "hrishys" did NOT say that "4 rows are missing
and each one for a multimillion order"
He said "Example the seq number is 38 and the table pk has a value of 42". A gap of 4 between a Sequence and the Primary Key doesn't always mean that 4 rows are missing. Furthermore, the 4 rows could be either for purchase orders of 1cent each or for employee usage of the coffee machine.
Have you heard of Sequences being Cached and sequence values "gone missing" even in Cheque Book Numbers and Invoice Numbers ? (Of course, I don't say that it results in a discrepancy between a Sequence and a Primary Key but it does mean that 4 "rows" have to be explained to Auditors. There are other ways to handle such cases.
Let's say that we are dealing with a database where 4 rows are for multimillion orders. Uh... .... I would think that it isn't always possible to "stop transactions" in such an application. For all we know "hrishys" may have been running a Test Migration/Upgrade. Sure, for the Production Migration/Upgrade, you can convince the CEO/CIO to "stop transactions". Again, we do not know how long the transactions have to be stopped to get a full export. 30minutes ? One hour ? 4 hours ?
Hemant K Chitale
At 02:01 PM Sunday, Yechiel Adar wrote:
>I beg to differ.
>Having sequences out of order means that you lost some data.
>In his example 4 rows are missing, each one for a multi million
>order that disappear from the books.
>You must stop transactions against the original database in cases of
>migrating the database to a new server.
>Hemant K Chitale wrote:
>>b. Generate a CREATE SEQUENCE script with values higher than the
>>current highest and use such a script at the target
Hemant K ChitaleReceived on Sun Mar 15 2009 - 09:39:07 CDT