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Thread: DBMS Vs RDBMS

  1. #1
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    Unanswered: DBMS Vs RDBMS

    Good Day !

    I am a newbie, to db world, and am going to be here for a long time to come.
    This forum has provided me answer to almost all my doubts and questions even without asking. Thanks to all the people who asked the questions and all those who contributed the answers.

    In a fictional scenario, if i have a few tables with the columns inter-related.
    In a DBMS Architecture, I can use INNER JOIN to access the data and do any particular operation i want to.

    What are the Pro's and Con's..performance wise ? security wise ?
    if is decide to switch to RDBMS.

    Are there any other factor that come into play here ? please enlighten me.
    Thanks in Advance.

  2. #2
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    if you have a DBMS which supports INNER JOIN, then switching to RDBMS is going to involve no pain whatsoever

    i suggest you google the terms DBMS and RDBMS and discover for yourself what the difference is

    rudy.ca | @rudydotca
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  3. #3
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    I assume by RDBMS, you mean relational database management system? This term was popular years ago before relational became the standard (network and hierarchical databases were the norm before that on mainframe computers). These days, almost all DBMS's are relational, although some new non-relational types are now emerging (mostly hype IMO).
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  4. #4
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    Several of my largest clients are still unable to go to DB2 (even though politically they really need to). They have not been able to migrate because even with all of the improvements in cpus, operating systems, and dasd, they still cannot handle their workload in DB2. What they use are databases where the code manages the access to the data, not SQL.

    I suspect that over time there will be even more improvements and even these larger sites will be able to run on DB2. By large i mean over 75tb of mainframe database data online supported by several dbms/rdbms offerings. A very small percent of this data is DB2. And this example is one of the smaller Large installations.

    Personally, i believe that if DB2 was not an IBM Program Product, it would have been pulled from the market place more than 20 years ago. . . fwiw.

  5. #5
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    I would be interested what the client of yours are doing where DB2 wouldn't be able to keep up with the requirements. I can understand that some clients may want to stick to IMS (or whatever) just because it works reliably for decade already and there is no technical need to change this. Another reason could be that changing a lot of legacy application comes with certain costs, which cannot be justified now.

    Handling several TBs of data (and 75TB is indeed a larger system) is usually not a problem these days - assuming that someone skilled does the database design and tuning.

    DB2 (on mainframes) was the first commercial relational database system. Everything else came after that. On technical terms, you will be hard pressed to find a system that is far superior. Or do you know about such a system since you claim that DB2 wouldn't be in the market any longer if it were not from IBM? Or are you just trolling?
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

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    Not trolling . . . No other database software vendor that i've worked with (been subcontracted by several) would have kept pushing a product that was so terribly inferior thru the 80's and 90's. Also, i keep forgetting that DB2 has been around for most of the years many people have been IT. My first database applicatiion "went live" Nov-Jan '69-70 . . .

    On technical terms, you will be hard pressed to find a system that is far superior.
    These days, i'd agree. The majority of the places that i've dealt with that cannot yet go to DB2 is largely a performance consideration. And as i mentioned, with more and more improvements in the cpus, the dasd, and the operating system (not to mention db2 itself) larger and larger systems can be successfully implemented under DB2.

    assuming that someone skilled does the database design and tuning.
    Many of the problem systems were directly converted from VSAM or some non-relational dbma and when these were done, there were not so many folks who used the relational approach. . .

    Another stopping point is the size of the application inventory that would need to be mostly re-written. Panels and reports might largely be salvaged, but all of the code that accesses data would need considerable modification.

  7. #7
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    Quote Originally Posted by papadi View Post
    Many of the problem systems were directly converted from VSAM or some non-relational dbma
    Well, you cannot really blame the database system for this, can you?

    and when these were done, there were not so many folks who used the relational approach. . .
    The bane of new technology. First the hype, then things come down to reality and then some people don't try to learn/adopt it where it may be appropriate. I don't think this is going to change anytime soon. :-)

    Anyway, I recommend that you grab some university course on database systems. Today, the foundations of relational systems are usually introduced there and it helps you to quickly get up to speed. After that, you can dive into the details of your specific database management system.
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

  8. #8
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    Quote Originally Posted by papadi View Post
    Personally, i believe that if DB2 was not an IBM Program Product, it would have been pulled from the market place more than 20 years ago. . . fwiw.
    Can you explain what you mean by that?
    M. A. Feldman
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    IBM Certified DBA on DB2 for z/OS and OS/390

  9. #9
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    Can you explain what you mean by that?
    OK, I'll try - and i don't really expect those who live and breathe db2 today to agree

    When db2 was first released, there were already many database systems to choose from and generally they performed well and were not labor intensive to administer. A very large number of organizations ran IMS (because of the high performance, but almost as important - because it came from IBM).

    The first several years of db2 were exercises in futility for almost everything but the rather trivial systems (not in importance, but data volume and transaction rates).

    If any of the other database vendors had delivered somthing that performed so poorly and required much more dba resource to manage, they would have either dropped their product or gone out of business. IBM knew where they wanted to go and had incredibly deep pockets to both fund the development as well as market db2.

    This is largely moot now as db2 currently has the majority of the mainframe database market share.

  10. #10
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    Quote Originally Posted by papadi View Post
    OK, I'll try - and i don't really expect those who live and breathe db2 today to agree

    When db2 was first released, there were already many database systems to choose from and generally they performed well and were not labor intensive to administer. A very large number of organizations ran IMS (because of the high performance, but almost as important - because it came from IBM).

    The first several years of db2 were exercises in futility for almost everything but the rather trivial systems (not in importance, but data volume and transaction rates).

    If any of the other database vendors had delivered somthing that performed so poorly and required much more dba resource to manage, they would have either dropped their product or gone out of business. IBM knew where they wanted to go and had incredibly deep pockets to both fund the development as well as market db2.

    This is largely moot now as db2 currently has the majority of the mainframe database market share.
    You seem to have tunnel vision, and a very distorted/warped view of history. A large number of organizations ran IMS because it was one of the few mainframe databases around. In terms of performance from a true DBMS (as opposed to a file system like VSAM), perhaps only IDMS could match or surpass it. IMS (and IDMS) were nightmares to use because, although they performed well, they are very labor intensive to do application development with and difficult to make changes to in a production environment. IMS and IDMS required highly skilled database designers and DBA's for even the simplest of tasks. I suspect you have felt left out because your skills are no longer as needed and venerated as they once were, and your complaints are the musings of a grumpy old man looking at the world through a rear-view mirror.

    Regarding other vendors, Oracle has had a mainframe version of their RDBMS for many years (not sure when it started, but at least since the late 1980's), although Oracle within the last couple of years has withdrawn their mainframe version from marketing/support because they cannot compete with DB2 for z/OS (which has always been a far superior RDBMS product on the mainframe). So your claim that if another vendor had a crappy product like DB2 for MVS during the 1990's they would have withdrawn it is completely untrue. Vendors don't withdraw products that sell, they only withdraw products that fail in the market place. In the 1980's and 1990's there were many UNIX databases that were crap, and I don't recall any of those vendors withdrawing their crappy database offerings during that time, because there was sufficient customer demand for them.

    It was Oracle, not IBM marketing, that really pushed the adoption of RDBMS and the move from the mainframe toward the UNIX/Linux platform (which I suppose you are also disgruntled about). IBM has been playing catch-up and attempting to make it less costly to develop on the mainframe, and DB2 is one of the things they offered to help in that regard. The move toward DB2 and away from rigid DBMS's like IMS was driven by customer requirements, not by IBM marketing.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

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    Quote Originally Posted by Marcus_A View Post
    IMS and IDMS required highly skilled database designers and DBA's for even the simplest of tasks.
    may i respectfully disagree here, as far as IDMS was concerned

    i was an IDMS developer/DBA, and hardly what you would call "highly skilled" either, and i found that working with IDMS was really easy

    especially for reporting, where we used Culprit for both simple and complex reports

    i also worked for Cullinane for a couple of years

    but then in 1987 i started working on DB2 with a product called Query Management Facility which ~really~ made reporting easy...

    ... because it used SQL
    rudy.ca | @rudydotca
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  12. #12
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    Quote Originally Posted by r937 View Post
    may i respectfully disagree here, as far as IDMS was concerned

    i was an IDMS developer/DBA, and hardly what you would call "highly skilled" either, and i found that working with IDMS was really easy

    especially for reporting, where we used Culprit for both simple and complex reports

    i also worked for Cullinane for a couple of years

    but then in 1987 i started working on DB2 with a product called Query Management Facility which ~really~ made reporting easy...

    ... because it used SQL
    Writing queries is not exactly what I had in mind. I was thinking of making schema changes. A single change of adding just one column on one segment required that all COBOL programs in the schema be recompiled. YIKES!!!

    When I worked on IDMS, the DBA team only released schema changes (even adding a single column) once a month, even in test. They told us that in some shops schema changes to prod only happened once every six months. With DB2 (and most other RDBMS's) a new column can be added on the fly without any downtime.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  13. #13
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    Quote Originally Posted by papadi View Post
    OK, I'll try - and i don't really expect those who live and breathe db2 today to agree

    When db2 was first released, there were already many database systems to choose from and generally they performed well and were not labor intensive to administer. A very large number of organizations ran IMS (because of the high performance, but almost as important - because it came from IBM).

    The first several years of db2 were exercises in futility for almost everything but the rather trivial systems (not in importance, but data volume and transaction rates).

    If any of the other database vendors had delivered somthing that performed so poorly and required much more dba resource to manage, they would have either dropped their product or gone out of business. IBM knew where they wanted to go and had incredibly deep pockets to both fund the development as well as market db2.

    This is largely moot now as db2 currently has the majority of the mainframe database market share.
    An interesting point of view... I wonder why Oracle still exists, why Microsoft started to develop SQL Server and why other companies like Sybase and Informix started to develop relational database systems. Granted, IBM delivered the first database system product more than 25 years ago, but why should those companies have started to work on something that "performed so poorly" as you say? Did they all set on the wrong technology? Or do you think that everyone else got things much better sorted out than IBM? Come on...
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

  14. #14
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    You seem to have tunnel vision, and a very distorted/warped view of history.
    Your opinion and only that. . . Actually, i'd be interested to hear where my "view of history" is mistaken. . .

    I suspect you have felt left out because your skills are no longer as needed and venerated as they once were, and your complaints are the musings of a grumpy old man looking at the world through a rear-view mirror.
    Actually far from "left out" - and you would have no clue. . . But again, just your opinion. In fact from things you post here, you typically sound much more grumpy than i . . .

    It was Oracle, not IBM marketing, that really pushed the adoption of RDBMS and the move from the mainframe toward the UNIX/Linux platform (which I suppose you are also disgruntled about).
    Probably not - as i was a senior sysadmin and dba on UNIX (HP-UX, AIX and Sun) for quite a few years . . . Possibly my most entertaining UNIX project was being the project lead to convert the entire application inventory running on 4 MVS mainframes to UNIX. This included all of the programming, screens, reports, database tables, and external files.

    I wonder why Oracle still exists, why Microsoft started to develop SQL Server
    Oracle has done quite well on UNIX systems. From what i've seen, the mainframe product was never done well, and so it was removed. And surely the more DB2 improved, the less attractive Oracle became. As less and less (big?) systems are being implemented on UNIX, i'm not sure how much new we'll see there (Only my current thought - might change).

    I believe Microsoft has done the same thing with database as IBM did with PCs. Once it was demonstrated that the Personal Computer could bring big business bucks, IBM jumped in and the term became IBM-compatible as they initially dominated the pc market. Just as most mainframe management wants their database to be from IBM, most Win-based management wants their database to be from MS. And SQLServer has become rather powerful from a load-bearing perspective - not counting the market share they enjoy.

    And yes, i do hope that the smaller database systems on all 3 platforms continue forward.

  15. #15
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    Quote Originally Posted by papadi View Post
    And yes, i do hope that the smaller database systems on all 3 platforms continue forward.
    In that respect, don't forget MySQL, and the current role of Oracle in it!
    --_Peter Vanroose,
    __IBM Certified Database Administrator, DB2 9 for z/OS
    __IBM Certified Application Developer
    __ABIS Training and Consulting
    __http://www.abis.be/

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