Hello Consultant , This is for the fellow consultants who are new to the DB environment and trying to understand from the start .Building block of Database : Rows , Column and Table.
Table :- Fundamental data structure in a relational database made up of set of columns.
Relations ---------(mapped)------ > Physical Tables
- Columns (Attribute of Relation)
Tables can be stored in Row Format and what makes HANA special is it can store in COLUMN format and Hana also allows conversion from ROW to COLUMN and vice versa . Though the end user will not feel the difference if row or column store. We can see impact of these on :-
2. Data Manipulations
3. Data Retrieval
The selection where it should be row store or column store need to used as per our usage and depends on optimal match between work process or workload within the application. In case of SAP it is taken care of by the Application Developer.
We also have other tables also :-
1. Temporary table
2. Flexible Schema
3. History Table
All these tables help in different Scenario as per our requirement but all the table has certain similarities and let's discuss on that first.
Common Properties of All the table
1. All Database Table defines relationship between columns.
2. Structure of Definition :-
Set of Column or field.
Each column has unique name within table.
Specific data types and primary key definition.
So all these Id, Name , Gender are attributes of the below mentioned table as the column names
And a record will be one entire line for E.g.: 102, Vishal, Male as in the rows
3. Table Definition : It is also known as the logical table , usually it contains the same thing as the structure along with semantic information , uniqueness constraint and primary key definition.
It contains the map to physical table where the chunk of values are saved
Concept :- Row :- Record/Tuple
Each data entry is a row
App connects with database with help of interface such as MDX, Odata, API(CE function - Part of HANA SQL Script) or the one that is widely used and you should be aware of SQL.
Regardless of type of table the interaction of Application based on table definitions , the end user / Application user won't feel a changes and retrieval process using the interface is same.
SQL command to perform actions are independent of row or column based storage.
- Independent from type of table
- Table definition is logical table , so how the table is stored won't make a difference we have the information where the chunk is stored and that is saved in row or column based storage.
We will dive in more in the coming blogs .
Inspired by HANA Admin book.