Fundamentals of SAP ABAP Tables

Transparent	Pool	Cluster
Contain a single table. Used to store master data	They are used to hold a large number of very small tables(stores customizing data or system data)	They are used to hold data from a few number of large tables.(stores system data)
It has a one-to-one relationship with a table in the database	It has a many-to-one relationship with a table in the database	It has a many-to-one relationship with table in the database
For each transparent table there is one associated table in the database	It is stored with other pooled tables in a single table called table pool in the database	Many cluster tables are stored in a single table in the database called a table cluster
The database table has the same name, same number of fields and the fields have the same names	The database table has different name, different number of fields and fields have different names	The database table has different name, different number of fields and fields have different names
There is only a single table	Table pools contain more tables than table clusters	Contains less tables than table pools
Single table can have one or more primary key	Primary key of each table does not begin with same fields or fields	Primary key of each table begins with same fields or fields
Secondary indexes can be created	Secondary indexes cannot be created	Secondary indexes cannot be created
They can be accessed using open and native SQL	They can be accessed using open SQL only	They can be accessed using open  SQL only
USE: They are used to hold master data e.g. Table vendors or table of customers. Example of transaction data is orders placed by customers	USE: They reduce the amount of database resources needed when many small tables have to be opened at the same time	USE: They would be used when the tables have primary key in common and data in these tables are all accesses simultaneously