Types of tables in SAP

Tables are used to store data. There are 3 types of tables in SAP.

  • Transparent
  • Cluster
  • Pooled
Transparent table: They have 1:1 relationship with the underlying database. Meaning for each transparent table there is one associated table in the database with exact same number of fields. We can either use NATIVE SQL or OPEN SQL to access TRANSP table. Secondary indexes can be created and buffering can be done in transparent table.
Ex: MARA, MARC
Pooled table: Used to hold large number of very small tables. Secondary indexes cannot be created.Primary key of each table does not begin with same fields or fields. (It can hold unrelated logical tables).

It has a many-to-one relationship with a table in the database.It is stored with other pooled tables in a single table called table pool in the database 

They can be accessed using open SQL only.
USE: They reduce the amount of database resources needed when many small tables have to be opened at the same time
Example : A018.

Cluster TableThey are used to hold small number of very large tables. Secondary indexes cannot be created. Primary key of each table begins with same fields or fields.(It holds related logical tables).

It has a many-to-one relationship with a table in the database.Many cluster tables are stored in a single table in the database called a table cluster.

They can be accessed using open SQL only. 
USE: They would be used when the tables have primary key in common and data in these tables are all accesses simultaneously
Example: BSEG