IDS Forum

Re: Offline Secondary

Posted By: Art Kagel
Date: Monday, 25 February 2013, at 10:45 a.m.

In Response To: Offline Secondary (Marcus Haarmann)

Continuous log restore has to start with a full restore of a level 0
archive (and possibly level1 & /or level 2 archives if you don't have
logical logs going back far enough). You cannot initiate continuous log
restore using an export/import. If you wanted to read the CLR secondary
you would have to put it into full online mode but to return it to CLR
"mode" you would have to restore another archive from the primary.

Another option would be to use the Change Data Capture API to capture
changes to the production database and apply them as SQL insert, update, &
delete statements to a "live" secondary that is always in a usable mode.
However, that server would, obviously, not be in a read-only state and
would require a full server license. Indeed, any secondary that you
actively read from, even periodically to export data to a data warehouse,
would require a full server license.

Have you considered buying the Informix Warehouse Accelerator (IWA)
instead? You can run it on a separate Intel/Linux machine connected to the
production server and periodically upload tables you need to perform
complex DW style queries against to it. Your BI tools would connect
directly to the production server, but their queries would actually be
satisfied by data from the IWA many times faster than most data warehouses
loaded into Informix, Oracle, DB2, or other RDBMS's without something like
IWA (and there ISN'T anything like IWA out there). I have seen queries run
400 times faster and more in IWA than in a 'normal' RDBMS. Most queries,
regardless of how much data is loaded into IWA or how complex the query is,
run in under 2 minutes many in under 2 seconds and all without placing any
strain on production queries or affecting the Informix cache's contents.
IWA has the ability to allow you to refresh the tables uploaded to it
periodically without performing another full upload.

If you are currently running Informix on Linux, you can upgrade to Informix
Ultimate Warehouse Edition for a reasonable additional license which is
usually less expensive than a full readable secondary server license.

Art

Art S. Kagel
Advanced DataTools (www.advancedatatools.com)
Blog: http://informix-myview.blogspot.com/

Disclaimer: Please keep in mind that my own opinions are my own opinions
and do not reflect on my employer, Advanced DataTools, the IIUG, nor any
other organization with which I am associated either explicitly,
implicitly, or by inference. Neither do those opinions reflect those of
other individuals affiliated with any entity with which I am affiliated nor
those of the entities themselves.

On Mon, Feb 25, 2013 at 8:20 AM, Marcus Haarmann
<marcus.haarmann@midoco.de>wrote:

> Hi experts,
>
> A customer wants to have a secondary read only instance as base for his
> DWH.
> The trick is that the server should have a consinstent state as read-only
> secondary,
> which is based on logical logfiles (like continous logical log restore,
> they
> want to be able
> to roll forward the logs up to a specific point in time/logs and then do
> ETL
> to their external DWH).
> And - no direct connectivity between the servers, we are only able to
> transfer
> backup
> files (Level 0 and Logs) via an intermediate system using sftp and setup
> some
> cron stuff
> to automatically process the logfiles when the time is reached.
> Of course, they do not want to transfer always the L0, but to export data
> and
> then
> rollforward the logs from the day to get to the next timepoint.
>
> Intended setup:
> - IDS11.70FCxGE with Linux as master instance
> - IDS11.70xCxIE (Innovator) with Linux as secondary instance
>
> Would that work ? By standard, continous logical log restore would leave
> the
> server
> in recovery mode and not allow any queries. Is it possible to set a server
> in secondary mode in this state, without having connectivity to the
> primary ?
> Anbody done this before ?
>
> Any thoughts are welcome !
>
> Thanks,
>
> Marcus Haarmann
> Geschäftsführer
>
> Midoco GmbH
> Otto-Hahn-Str. 12
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>
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Messages In This Thread

• Offline Secondary
  Marcus Haarmann -- Monday, 25 February 2013, at 8:20 a.m.
  • Re: Offline Secondary
    Art Kagel -- Monday, 25 February 2013, at 10:45 a.m.
  • Re: Offline Secondary
    Nagaraju Inturi -- Tuesday, 26 February 2013, at 2:28 p.m.

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