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IDS Forum
RE: CDC API - Change database
Posted By: LARRY SORENSEN
Date: Monday, 12 September 2011, at 1:20 p.m.
In Response To: Re: CDC API - Change database (Art Kagel)
Thank you to Art and Madison for their indulgence and exhaustive explanation. I think it is finally starting to clear up for me. IBM just does not have a very good explanation/description for any of this.
Larry
> To: ids@iiug.org
> From: art.kagel@gmail.com
> Subject: Re: CDC API - Change database [24893]
> Date: Mon, 12 Sep 2011 13:14:22 -0400
>
> 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
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
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> > > >
> > > >
> > >
> > >
> >
> >
> *******************************************************************************
> > >
> > > >
> > > > > > > > Forum Note: Use "Reply" to post a response in the discussion
> > > forum.
> > > >
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > > --bcaec52994bb61579604ac5a5977
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> *******************************************************************************
> > >
> > > >
> > > > > > > Forum Note: Use "Reply" to post a response in the discussion
> > forum.
> > >
> > > > > > >
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> > >
> > > >
> > > > > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > > > > >
> > > > > >
> > > > >
> > > > > --90e6ba6e844092372204ac5baf59
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> > >
> > > >
> > > > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > > > >
> > > >
> > > >
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> *******************************************************************************
> > >
> > > >
> > > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > > >
> > > >
> > > >
> > >
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> *******************************************************************************
> > >
> > > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > > >
> > >
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> *******************************************************************************
> > >
> > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > >
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> > > Forum Note: Use "Reply" to post a response in the discussion forum.
> > >
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> *******************************************************************************
> > Forum Note: Use "Reply" to post a response in the discussion forum.
> >
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> --20cf303bfaae00f60704acc1a829
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> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
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