IDS Forum

Re: CDC API - Change database

Posted By: Art Kagel
Date: Monday, 12 September 2011, at 1:14 p.m.

In Response To: RE: CDC API - Change database (LARRY SORENSEN)

See below:

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, Sep 12, 2011 at 1:00 PM, LARRY SORENSEN <lsorensen25@msn.com> wrote:

> OK. I just read the manual. Let me see if I have the flow correctly..
>
> 1) Run the sql script to set up the CDC database (The database and CDC now
> lays dormant until you write a program that opens a sessions and starts
> reading the logs.
>

Yes

> 2) Write the program to connect to the CDC database and start processing
> transaction logs. This can run continuously until stopped or run
> occassionally.
>
Yes

> 3) No actual changed data is stored in the CDC database. It is only
> metadata
> on where you are in the log records you have been processing.
>
Yes

> 4) The program itself determines which tables to access change data on when
> reading the transaction logs. Table information is not stored in the CDC
>
Correct.

> database? (This part is unclear to me. If my target database is already
> logging, is it the CDC database that I am turning on logging for my table
> or
> are you just making sure that my target database is logging? Does the CDC
> database actually hold any of my data that I am trying to capture or is it
> as
> I said, just metadata.
>
The main thing that the cdc database holds that is user usable, is
descriptions of error codes and log record types. See the description of
the syscdcerrcodes and syscdcrectypes tables

>
> I am sorry about all of these questions. I am still trying to decide what
> amount of effort will be required for this and what the CDC API actually
> does
> for me automatically.
>
Not much. It is an API used for doing things yourself. If you want
automatic replication look to Enterprise Replication, or MACH11
secondaries. If you want automatic change auditing, look to the Informix
Secure Audit Facility. Or purchase one of the IBM or 3rd party tools I
mentioned (and others) that will use the API to automate these things for
you.

> Larry
>
> > To: ids@iiug.org
> > From: mpruet@us.ibm.com
> > Subject: RE: CDC API - Change database [24890]
> > Date: Mon, 12 Sep 2011 10:23:17 -0400
> >
> > The CDC API is used if you are going to a non-Informix database. If you
> > are planning on replicating between two Informix databases, you should
> use
> > ER.
> >
> > The CDC API is using basic SQL commands to capture the log changes. The
> > SQL script is used to create a database and the hooks into the internal
> > code which make up the API. This is done by creating several UDRs which
> > interface with the logs. You obtain the changed data from the logs by 1)
> > executing a procedure in that database to turn on full logging for the
> > requested table and then 2) specifying what table you want to capture.
> > Once you activate the capture, then you receive the log changes from a
> > pseudo smart blob. These interfaces are all provided by the SQL script
> > that you need to run to enable the CDC API.
> >
> > I'd suggest reading the CDC API manual (SC27-3527-00)
> >
> > M.P.
> >
> > From: "LARRY SORENSEN" <lsorensen25@msn.com>
> >
> > To: ids@iiug.org
> >
> > Date: 09/12/2011 09:06 AM
> >
> > Subject: RE: CDC API - Change database [24889]
> >
> > Sent by: ids-bounces@iiug.org
> >
> > I am looking for something that just provides that changes to the tables
> > that
> > I select. Is the CDC API a manual process. I was under the assumption
> that
> > it
> > was something that you could turn on and then it was continuous.
> >
> > What it is sounding like is....
> >
> > I need to write a C program. Somehow, I run that program occassionally
> > against
> > the log files to capture the changes that occurred in the tables that I
> am
> > watching. Is that somewhat accurate?
> >
> > If so, why is that sql script needed to set things up if everything is
> just
> >
> > manual and the change data does not end up in a database?
> >
> > Is there a book or something that explains the process a little better
> than
> >
> > the InfoCenter does?
> >
> > Larry
> >
> > > To: ids@iiug.org
> > > From: mpruet@us.ibm.com
> > > Subject: RE: CDC API - Change database [24888]
> > > Date: Mon, 12 Sep 2011 09:56:20 -0400
> > >
> > > The CDC API is API for Change Data Capture. I think that you might be
> > > confusing the API with Infosphere Change Data Capture. The CDC API
> > > provides the means of capturing the changes made to a database. It is
> not
> >
> > > data replication
> > >
> > > The CDC API is an API which provides the ability to snoop the logical
> > logs
> > > to capture the changes in the database. It does not apply those changes
> > to
> > > a target. If you want to apply the changes to a different database, you
> > > would need to use Infosphere Change Data Capture (i.e. DataMirror). or
> > > write your own capture/apply program.
> > >
> > > From: "LARRY SORENSEN" <lsorensen25@msn.com>
> > >
> > > To: ids@iiug.org
> > >
> > > Date: 09/12/2011 08:38 AM
> > >
> > > Subject: RE: CDC API - Change database [24887]
> > >
> > > Sent by: ids-bounces@iiug.org
> > >
> > > Is there any better documentation on the CDDC API? I have looked in the
> > > Information Center documentation and it does not explain much. It says
> to
> >
> > > run
> > > the syscdcv1.sql script to do the initial setup, but then it gets
> fuzzy.
> > >
> > > 1) It mentions accessing the data using C programs that I develop. It
> > does
> > > really explain how the data gets into the new database. It hints at
> > > creating a
> > > program to capture the data and put it into the new database, but I
> > thought
> > >
> > > that was the CDC API's job. It appears that I use a tool like DBAccess
> to
> >
> > > run
> > > sql to set up the change monitoring. Is that true, and does the data
> > appear
> > >
> > > automatically in the new database after that?
> > >
> > > 2) Can't I just access the data like I would a regular database? It is
> > > unclear
> > > what the table names will be for the data. Is it the same name as the
> > table
> > > in
> > > the original database where the changes were made?
> > >
> > > It is frustrating that IBM/Informix provides a tool like the CDC API,
> but
> >
> > > has
> > > very little documentation on how to use it if you are wanting to use it
> > for
> > >
> > > the first time. Does anyone else have any experience with the CDC API?
> I
> > > can't
> > > even find enough information to make an informed decision on whether I
> > can
> > > use
> > > if for my needs or not.
> > >
> > > Larry
> > >
> > > > To: ids@iiug.org
> > > > From: art.kagel@gmail.com
> > > > Subject: Re: CDC API - Change database [24877]
> > > > Date: Wed, 7 Sep 2011 11:34:58 -0400
> > > >
> > > > Built-in but you need to initialize it by creating the syscdcv1
> > database
> > > and
> > > > installing the stored procedures that implement the functionality.
> > There
> > > is
> > > > a script, $INFORMIXDIR/etc/syscdcv1.sql, that you execute to do that.
> > See
> > >
> > > > the Change Data Capture Programmer's Guide for details.
> > > >
> > > > 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 Wed, Sep 7, 2011 at 11:20 AM, LARRY SORENSEN <lsorensen25@msn.com
> >
> > > wrote:
> > > >
> > > > > Thank you for the clarification. Do I need to install it, or is it
> > > already
> > > > > built in and I just use it?
> > > > >
> > > > > Larry
> > > > >
> > > > > > To: ids@iiug.org
> > > > > > From: art.kagel@gmail.com
> > > > > > Subject: Re: CDC API - Change database [24872]
> > > > > > Date: Wed, 7 Sep 2011 09:59:17 -0400
> > > > > >
> > > > > > OK: CDC API is free and included with Informix. There is a manual
> > for
> > >
> > > how
> > > > > > to use it included in the manual set.
> > > > > >
> > > > > > InfoCenter CDC is a separate product, a kind of intra-RDBMS ETL
> > > > > > tool that uses the CDC API. This is the chargeable product.
> > > > > >
> > > > > > 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 Wed, Sep 7, 2011 at 9:47 AM, LARRY SORENSEN
> > <lsorensen25@msn.com>
> > > > > wrote:
> > > > > >
> > > > > > > I have had a lot of good responseses from my previous query.
> The
> > > only
> > > > > > > problem
> > > > > > > that I am having now is the following:
> > > > > > >
> > > > > > > >From one source, I am told that the CDC API is not included
> with
> >
> > > > > Informix
> > > > > > > and
> > > > > > > is an item requiring purchase (Software vendor).
> > > > > > >
> > > > > > > >From another source I am told that this is a free item (tech
> > > support).
> > > > > > >
> > > > > > > I am not sure which is correct, nor do I still know where I can
> > get
> > >
> > > the
> > > > > > > software for the API. Can anyone provide clarification on this?
> > > > > > >
> > > > > > > Also, is this CDC API that same as the IBM product, Infocenter
> > CDC;
> > > or
> > > > > are
> > > > > > > they two different products?
> > > > > > >
> > > > > > > Larry
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
> >
>
> *******************************************************************************
> >
> > >
> > > > > > > Forum Note: Use "Reply" to post a response in the discussion
> > forum.
> > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > > > --bcaec52994bb61579604ac5a5977
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
> >
>
> *******************************************************************************
> >
> > >
> > > > > > Forum Note: Use "Reply" to post a response in the discussion
> forum.
> >
> > > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
> >
>
> *******************************************************************************
> >
> > >
> > > > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > > > >
> > > > >
> > > >
> > > > --90e6ba6e844092372204ac5baf59
> > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
> *******************************************************************************
> >
> > >
> > > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > > >
> > >
> > >
> > >
> >
> >
>
> *******************************************************************************
> >
> > >
> > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > >
> > >
> > >
> >
> >
>
> *******************************************************************************
> >
> > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > >
> >
> >
> >
>
> *******************************************************************************
> >
> > Forum Note: Use "Reply" to post a response in the discussion forum.
> >
> >
> >
>
> *******************************************************************************
> > Forum Note: Use "Reply" to post a response in the discussion forum.
> >
>
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

--20cf303bfaae00f60704acc1a829

Messages In This Thread

• RE: CDC API - Change database
  LARRY SORENSEN -- Wednesday, 7 September 2011, at 9:47 a.m.
  • Re: CDC API - Change database
    Art Kagel -- Wednesday, 7 September 2011, at 9:59 a.m.
    • RE: CDC API - Change database
      LARRY SORENSEN -- Wednesday, 7 September 2011, at 11:20 a.m.
      • Re: CDC API - Change database
        Art Kagel -- Wednesday, 7 September 2011, at 11:34 a.m.
        • RE: CDC API - Change database
          LARRY SORENSEN -- Monday, 12 September 2011, at 9:36 a.m.
          • RE: CDC API - Change database
            Madison Pruet -- Monday, 12 September 2011, at 9:56 a.m.
            • RE: CDC API - Change database
              LARRY SORENSEN -- Monday, 12 September 2011, at 10:04 a.m.
              • RE: CDC API - Change database
                Madison Pruet -- Monday, 12 September 2011, at 10:23 a.m.
                • RE: CDC API - Change database
                  LARRY SORENSEN -- Monday, 12 September 2011, at 1:00 p.m.
                  • Re: CDC API - Change database
                    Art Kagel -- Monday, 12 September 2011, at 1:14 p.m.
                    • RE: CDC API - Change database
                      LARRY SORENSEN -- Monday, 12 September 2011, at 1:20 p.m.
              • Re: CDC API - Change database
                Art Kagel -- Monday, 12 September 2011, at 12:52 p.m.

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