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Posted to dev@trafodion.apache.org by Carol Pearson <ca...@gmail.com> on 2015/11/20 19:45:02 UTC
Question re Transaction Logs
Hi,
I'm updating the Trafodion FAQ as part of the website migration. One of
the questions in the current FAQ is:
Is there a transaction log and can the log be shipped to a DR site?
Yes, there is a log that audits all the transactional activity. There is no
support for shipping and replaying the log on a remote DR site.
https://wiki.trafodion.org/wiki/index.php/FAQ#Is_there_a_transaction_log_and_can_the_log_be_shipped_to_a_DR_site.3F
Are singleton transactions included in the transaction log? My
understanding is that the TM doesn't get involved in singletons like
"INSERT INTO T VALUES (1,1);" if there's no index on table T.
So should this FAQ answer just say that Trafodion does not generate a
complete transaction log that can be used to replicate the entire database
on a remote system? Or am i missing something?
Thanks!
-Carol P.
---------------------------------------------------------------
Email: carol.pearson234@gmail.com
Twitter: @CarolP222
---------------------------------------------------------------
Re: Question re Transaction Logs
Posted by Carol Pearson <ca...@gmail.com>.
Thanks Sean! This was very helpful!
-Carol P.
---------------------------------------------------------------
Email: carol.pearson234@gmail.com
Twitter: @CarolP222
---------------------------------------------------------------
On Fri, Nov 20, 2015 at 10:53 AM, Sean Broeder <se...@esgyn.com>
wrote:
> Hi Carol,
> There is the standard HBase HLog, but we do not currently have the ability
> to support replication to a DR site because we can't ensure transaction
> consisteny on the remote site for transactions that span multiple HLogs
> (WAL)s
>
> Also, you are right that there is currently a short circuit for single
> region/single row operations that skip the DTM, but that is a bug that
> cannot be supported. It skips conflict checking and there is no relation
> maintained to prior of subsequent operations. So this can result in
> undetected conflicts.
>
> I do have on my plate a project to introduce autonomous region transactions
> that will bypass the DTM, but still perform conflict checking in the
> regions.
>
> Regards,
> Sean
>
> -----Original Message-----
> From: Carol Pearson [mailto:carol.pearson234@gmail.com]
> Sent: Friday, November 20, 2015 10:45 AM
> To: dev@trafodion.incubator.apache.org
> Subject: Question re Transaction Logs
>
> Hi,
>
> I'm updating the Trafodion FAQ as part of the website migration. One of
> the
> questions in the current FAQ is:
>
> Is there a transaction log and can the log be shipped to a DR site?
>
> Yes, there is a log that audits all the transactional activity. There is no
> support for shipping and replaying the log on a remote DR site.
>
>
>
> https://wiki.trafodion.org/wiki/index.php/FAQ#Is_there_a_transaction_log_and_can_the_log_be_shipped_to_a_DR_site.3F
>
> Are singleton transactions included in the transaction log? My
> understanding is that the TM doesn't get involved in singletons like
> "INSERT
> INTO T VALUES (1,1);" if there's no index on table T.
>
> So should this FAQ answer just say that Trafodion does not generate a
> complete transaction log that can be used to replicate the entire database
> on a remote system? Or am i missing something?
>
> Thanks!
> -Carol P.
>
> ---------------------------------------------------------------
> Email: carol.pearson234@gmail.com
> Twitter: @CarolP222
> ---------------------------------------------------------------
>
RE: Question re Transaction Logs
Posted by Sean Broeder <se...@esgyn.com>.
Hi Carol,
There is the standard HBase HLog, but we do not currently have the ability
to support replication to a DR site because we can't ensure transaction
consisteny on the remote site for transactions that span multiple HLogs
(WAL)s
Also, you are right that there is currently a short circuit for single
region/single row operations that skip the DTM, but that is a bug that
cannot be supported. It skips conflict checking and there is no relation
maintained to prior of subsequent operations. So this can result in
undetected conflicts.
I do have on my plate a project to introduce autonomous region transactions
that will bypass the DTM, but still perform conflict checking in the
regions.
Regards,
Sean
-----Original Message-----
From: Carol Pearson [mailto:carol.pearson234@gmail.com]
Sent: Friday, November 20, 2015 10:45 AM
To: dev@trafodion.incubator.apache.org
Subject: Question re Transaction Logs
Hi,
I'm updating the Trafodion FAQ as part of the website migration. One of the
questions in the current FAQ is:
Is there a transaction log and can the log be shipped to a DR site?
Yes, there is a log that audits all the transactional activity. There is no
support for shipping and replaying the log on a remote DR site.
https://wiki.trafodion.org/wiki/index.php/FAQ#Is_there_a_transaction_log_and_can_the_log_be_shipped_to_a_DR_site.3F
Are singleton transactions included in the transaction log? My
understanding is that the TM doesn't get involved in singletons like "INSERT
INTO T VALUES (1,1);" if there's no index on table T.
So should this FAQ answer just say that Trafodion does not generate a
complete transaction log that can be used to replicate the entire database
on a remote system? Or am i missing something?
Thanks!
-Carol P.
---------------------------------------------------------------
Email: carol.pearson234@gmail.com
Twitter: @CarolP222
---------------------------------------------------------------