oracle11g - database for enterprise level using oracle - normalization and duplication -


I am developing an enterprise application with an Oracle backend. I am now preparing the main part of the DB architecture and I am having some questions on IM.

  1. The first and foremost thing is that, most of my tables need to preserve the old data. For example

    Consider a table with the field

    contract number, contract name, person of contract, contract email

    my Have a record like

    12, xxx, yyy, xxx@zzz.ccc

    and anything else

    12, xxx, zzz, xxx @ zzz. Ccc

    At any time, I need to display new records, whereas the old record is a copy.

    So I thought that putting a duplicate record of old data and updating has changed the field and there is a flag to keep track of active records, like something like "active" .

    The downside is that it makes redundancy in the table and looks like a bad design but any other model looks unnecessarily complex and it looks cleaner for me except for anyone with duplicate records I do not even see the performance issues. So please tell me whether it is ok or I'm missing something here.

    1. For some time where there are many relations, I think that the mapping table is where I map, repeating the master ID and changing the child ID in each record, Is there a right way to do this or is there a better way to do this.

    2. Is the database a book on best practices.

      Thank you.

      Assume that over time, he has 15 updates, which is also a duplicate record.

      If you do not store any temporary data (if you do not store different versions of the row), then you store a line if you store temporary data, you store 15 rows

      You also need more indexing, because ID number is no longer sufficient to identify a single line.

      If you have only small tables, you probably will not see any performance difference. (There will be , but it will probably not be noticeable for users.) But a table that has 10 million rows, will perform differently from the table, which has 150 million rows. (15 versions per line, 10 million rows per line.)

      Many times where there are many links, I think that is the mapping table where I map multiple units to individual records. Master ID Repeating and changing the Child Ids in each record. Is there a right way to do this or is there a better way of doing this?

      You probably need to know which rows are from the original parental rows. You need more than a master ID for the key. Master ID simply does not tell you which version of that line in the original line is applied to a given hair row.

      Is the database a book on best practices.

      There are books on the temporal database. I know that the first is a Snodgrass, it is available in many formats, and it's free. It is also old, but it is important to understand that if you are going to build a temporary database, think about reading the date book temporal data and relational model .

      Wikipedia has an article that summarizes.

      Whether generalization is completely mandatory.

      It is a meaningless question that you will have different problems with normalized tables of 2NF, with generalized tables for 5 NF or 6 NF.

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