Difference between ROLAP, MOLAP and HOLAP

1. Relational Online Analytical Processing (ROLAP) :
ROLAP servers are placed between relational backend server and client front-end tools. It uses relational or extended DBMS to store and manage warehouse data. ROLAP has basically 3 main components: Database Server, ROLAP server, and Front-end tool.

Advantages of ROLAP –

  • ROLAP is used for handle the large amount of data.
  • ROLAP tools don’t use pre-calculated data cubes.
  • Data can be stored efficiently.
  • ROLAP can leverage functionalities inherent in the relational database.

Disadvantages of ROLAP –

  • Performance of ROLAP can be slow.
  • In ROALP, difficult to maintain aggregate tables.
  • Limited by SQL functionalities.

2. Multidimensional Online Analytical Processing (MOLAP) :
MOLAP does not uses relational database to storage.It stores in optimized multidimensional array storage. The storage utilization may be low With multidimensional data stores. Many MOLAP server handle dense and sparse data sets by using two levels of data storage representation. MOLAP has 3 components : Database Server, MOLAP server, and Front-end tool.

Advantages of MOLAP –

  • MOLAP is basically used for complex calculations.
  • MOLAP is optimal for operation such as slice and dice.
  • MOLAP allows fastest indexing to the pre-computed summarized data.

Disadvantages of MOLAP –

  • MOLAP can’t handle large amount of data.
  • In MOLAP, Requires additional investment.
  • Without re-aggregation, difficult to change dimension.

3. Hybrid Online Analytical Processing (HOLAP) :
Hybrid is a combination of both ROLAP and MOLAP.It offers functionalities of both ROLAP and as well as MOLAP like faster computation of MOLAP and higher scalability of ROLAP. The aggregations are stored separately in MOLAP store. Its server allows storing the large data volumes of detailed information.

Advantages of HOLAP –