RE: Oracle High Availability Question(s)

From: Reen, Elizabeth <"Reen,>
Date: Fri, 16 Feb 2018 16:19:59 +0000
Message-ID: <>

                We went back to the app team.  An account cannot be both active and inactive at the same time.  I’m in the process of cleaning up a billion records from a 5 billion record table.  I don’t want to think about trying to fix this a month later.

Liz, who is chagrinned at the auto spell check changes

From: Ls Cheng [] Sent: Friday, February 16, 2018 11:17 AM To: Reen, Elizabeth [ICG-IT]
Cc: Chris Taylor; Tim Gorman; Scott Canaan;; Subject: Re: Oracle High Availability Question(s)

In our case someone noticed the difference after a month. If this was reported in the initial load we would have done something else (open the SR before go live for example). Have you used KELCOLS before?

On Fri, Feb 16, 2018 at 5:13 PM, Reen, Elizabeth <<>> wrote:

                Agreed that GG will handle the differences, I’m just saying that unless you make the whole record a PK ( and I have had to do that) it is possible to have dups on one side and not the other.  That it was not reporting that the records were not inserted is the bug to me.  I had a similar issue with a table that had an active indicator.  On one system records where there with the indicator set to Y and N.  It worked on one system because the PK was the whole record.  I blew up on the other system because they did not include the indicator as part of the OK.  I would expect GG to report the error.  The issue was found during the initial load.


From: Ls Cheng [<>] Sent: Friday, February 16, 2018 10:57 AM

To: Reen, Elizabeth [ICG-IT]
Cc: Chris Taylor; Tim Gorman; Scott Canaan;<>;<> Subject: Re: Oracle High Availability Question(s)

We know how to handle table with different PK with KEYCOLS, precisely that is what we did but it turns out a bug which happens only in Integrated Extract (Classic Extract handle this correctly). It is not a bug we invented, we opened a SR and after 3 weeks support finally admitted it as bug and being worked by development. By the way the table does not need be exactly the same in OGG. Our use case is replicating operational database to historical database. BR

On Fri, Feb 16, 2018 at 4:44 PM, Reen, Elizabeth <<>> wrote:

                The objects have to be the same to be replicated.  A different PK may allow duplicates on one database which are not possible on the other.  It should have flagged the error, but I don’t see this as a bug.  A pk on orders would have duplicate accounts.  A PK on accounts would blow up with dups.


From: Ls Cheng [<>] Sent: Friday, February 16, 2018 10:35 AM To: Reen, Elizabeth [ICG-IT]
Cc: Chris Taylor; Tim Gorman; Scott Canaan;<>;<>

Subject: Re: Oracle High Availability Question(s)

Hello Elisabeth
Our were not application issues. It was OGG bugs which ignored DML operations. If a replication software cannot guarantee replicate all DML operations then we have a big problem. BR

On Fri, Feb 16, 2018 at 3:57 PM, Reen, Elizabeth <<>> wrote: GG requires that you understand the app. It also requires that you make the changes in both DBs. It’s not unpredictable, you just need to stay on top of it and the changes. We ran into all sorts of sequence issues. It turns out that the app was not using sequences but reading the max and adding 1. GG will find all of the weaknesses in your code.


From:<> [<>] On Behalf Of Ls Cheng Sent: Thursday, February 15, 2018 5:50 PM To: Chris Taylor
Cc: Tim Gorman; Scott Canaan;<>;<> Subject: Re: Oracle High Availability Question(s)


Just some warning with GoldenGate.

Recently we had a big issue with GoldenGate in the most critical database in one of or customers. GoldenGate ignored all updates in target because the target and source had different PK (target had same table structure as source but partitioned so PK had an additional column, the partitioning key), just because of different PK even we knew that and specified KEYCOLS in the target the updates was ignored until 1 month later a data analyst noticed some data divergence and adviced our support team. We had to restore 4 backups (each 4TB) to recover the data. It turns out bug 26553124 and there werent even a Alert in MOS explaining such behaviour. Lesson learnt. GoldenGate is unpredictable, this is the second time in 2 years I see such data divergence due to GoldenGate bug and the impact is huge, huge and huge because data divergence is soooo difficult to detect. So for DR stick with Data Guard (Physical Standby). I consider RAC as HA because you have several nodes available for a single copy of data (I consider DR more than one copy of data) and the death of one node still makes the application available, only 100%/number of nodes is impacted and the recovery is fast. Thanks

On Thu, Feb 15, 2018 at 8:47 PM, Chris Taylor <<>> wrote: What about GoldenGate Tim??

(Since I find myself trying to support this with no training/prior experience and learning in the deep end of the pool.... :)


On Wed, Feb 14, 2018 at 3:23 PM, Tim Gorman <<>> wrote: Going into Data Guard without training is uncomfortable, but going into RAC without training is untenable. You can try it, but it is going to hurt a lot, and you'll end up with something you'll regret.


Received on Fri Feb 16 2018 - 17:19:59 CET

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