Architecture and Data Blog

Many IT organizations I have seen have groups of specialists, typical are UNIX Group, DBA group etc.

When a project starts the developers on the project have to meet with all the Groups (I have more experience with the DBA group, so I write with the DBA group in mind) that they need to interact with and explain to the groups their design, the projects operational needs and other requirements, later when development starts they have to email these groups about all the setup that needs to be done and also the day to day changes that are needed. This way of working slows down the productivity of the team and the organization.

In development mode you don’t want to worry about which table goes into what Tablespace in production as it complicates development environments. The production DBA’s want to have their input and control over deciding what table goes into what Tablespace. To allow for this I used a mapping scheme as shown below.

Lets assume we have 3 tables in our system Customer, CustomerOrder, OrderStatus. Where we are expecting Customer table to have large numbers of rows and CustomerOrder to have significanly large number of rows while OrderStatus would have few rows and not change as much. In development environments all these tables and their indexes will be put under the same tablespace. In production like environments we want to put them into seperate tablespaces.

Database designs I have seen tend to not constrain the data in the database. For example make the Item.ManufacturerID non-nullable and make it a foreign key to the Manufacturer table. Similarly Manufacturer.Name and Item.Rate as non-nullable columns. In any greenfield application (existing production application is a topic for another post). When you design table(s) lets say you have Item and Manufacturer table as shown below

CREATE TABLE Item
(ItemID NUMBER NOT NULL,
ManufacturerID NUMBER,
Name VARCHAR2(128),
Rate NUMBER,
CONSTRAINT PK_ITEM
              PRIMARY KEY (ItemID)
);

CREATE TABLE Manufacturer
(ManufacturerID NUMBER NOT NULL,
Name VARCAHR2(128),
CONSTRAINT PK_MANUFACTURER
              PRIMARY KEY (ManufacturerID)
);

For now let’s talk about NOT NULL constraint. Many say they don’t make columns non-nullable, because they don’t know the requirements at design time, or they don’t want their tests to create elaborate sets of data, or that the application enforces the constraint then why enforce the constraint on the database?

Why is that many a time I say something and the person hears something else.

I have been wondering is it me or is it just the way people listen or interpret my words. How can I communicate better, making it easier for myself and cause less of an hassle for myself and all the ones around me.

When I get to the bottom of this, it will be one heck of an achievement.