Cobol's File System Vs. RDBMs...
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From: Richard on 24 Jul 2008 15:05 On Jul 25, 5:51 am, softWare design <sabra...(a)baxglobal.com> wrote: > On Jul 23, 3:55 pm, Richard <rip...(a)azonic.co.nz> wrote: > > > What survey data did use to come to this conclusion ? > > The inability to insert new columns into an existing index file. > You have to create a new index file and then transfer the old > data into the new file, change the copybook and recompile > every program that accesses the file, whether or not they > care about the new columns. Your response doesn't appear to cover how you decided that 'most Cobol developers came to the conclusion ..'. It seems that _you_ concluded something or other and then claimed massive silent support. Adding a new column in a database does not get it populated with appropriate data. Existing programs that don't reference the column will insert it as Null, or will fail if they haven't constructed the INSERT to cater for unreferenced columns.
From: softWare design on 24 Jul 2008 15:37 On Jul 24, 11:17 am, Howard Brazee <how...(a)brazee.net> wrote: > > This leads me to ask: > 1. What do you man by columns in an index file? > 2. What is the relationship between being open or closed and being > able to add columns? > Suppose I want to change my data model by adding a column to a table (field to a file record). With a relational database I add the column and the job is done. Any program that needs to work with that new column can on-the-fly, and any existing programs that do not care about the change stays untouched. The Cobol index file system is considered to be Closed simply because it requires a knowledge of the file definition/structure, in order to access the stored data. An open file system should allow privileged users to access the data and generate queries on-the-fly in the desired format they need, and facilitates any column insertions without the need to write special programs.
From: Richard on 24 Jul 2008 16:07 On Jul 25, 7:37 am, softWare design <sabra...(a)baxglobal.com> wrote: > On Jul 24, 11:17 am, Howard Brazee <how...(a)brazee.net> wrote: > > > > > This leads me to ask: > > 1. What do you man by columns in an index file? > > 2. What is the relationship between being open or closed and being > > able to add columns? > > Suppose I want to change my data model by adding a column > to a table (field to a file record). With a relational database > I add the column and the job is done. Any program that needs > to work with that new column can on-the-fly, and any existing > programs that do not care about the change stays untouched. > > The Cobol index file system is considered to be Closed simply > because it requires a knowledge of the file definition/structure, > in order to access the stored data. An open file system should > allow privileged users to access the data and generate queries > on-the-fly in the desired format they need, and facilitates any > column insertions without the need to write special programs. You seem to be confused between what you call 'my data model' and the business's data model. If you have specific needs then you can extract data from the business system and add your own data. If you want these 'extra columns' to contain _meaningful_ data then you would need to change the business system (input screens, update processes) to maintain these items correctly, and not just slap on a couple of extras and hope. Whether the system is 'open' or 'closed' certainly does depend on whether the system provides descriptions of the data and means to access it. This is _NOT_ a function of the file system, but of the application and the administration. My COBOL systems that are still based on indexed files provide a 'report writer' interface that allows for printed reports, CSV files and even HTML to be created by the user and has an interface that gives the user the ability to create such reports using a GUI. Fujitsu COBOL indexed files can also be read by Crystal Reports. All that is required is that the developers provide the schemas. RDBMS generally do provide the column names but this is only part of the issue, it is also necessary to understand what the data is.
From: Howard Brazee on 24 Jul 2008 16:09 On Thu, 24 Jul 2008 12:37:33 -0700 (PDT), softWare design <sabraham(a)baxglobal.com> wrote: >On Jul 24, 11:17�am, Howard Brazee <how...(a)brazee.net> wrote: >> >> This leads me to ask: >> 1. � What do you man by columns in an index file? >> 2. � What is the relationship between being open or closed and being >> able to add columns? >> > > >Suppose I want to change my data model by adding a column >to a table (field to a file record). With a relational database >I add the column and the job is done. Any program that needs >to work with that new column can on-the-fly, and any existing >programs that do not care about the change stays untouched. > >The Cobol index file system is considered to be Closed simply >because it requires a knowledge of the file definition/structure, >in order to access the stored data. An open file system should >allow privileged users to access the data and generate queries >on-the-fly in the desired format they need, and facilitates any >column insertions without the need to write special programs. > You have a unique view of what "open" and "closed" mean in our industry.
From: softWare design on 24 Jul 2008 18:17
On Jul 23, 6:28 pm, "Pete Dashwood" <dashw...(a)removethis.enternet.co.nz> wrote: > > I agree with you that the COBOL file system is "closed", inasmuch as you > need to write a COBOL (or other) program which knows the structure of it, in > order to access it. Certainly, some systems have ODBC drivers that permit > access but the basic problem is that, unlike a DBMS, the structure of the > data is not held in the file... (there is no metadata). > > This means that unless you can write a program or get one written, you can't > access it. (Compare this with an RDBMS, for example, where anyone who knows > SQL and has the right permissions can access the data.) > I understand that RDBMs offers greater visibility to the file contents, but how about performance considerations? Can a relational database file system slows down the Cobol application? Are there any performance bottlenecks when Cobol application handles large volume of data? Will Cobol application take much longer to run if I/O operations access the RDBMs file system as if they were ISAM files? |