What is Data Warehouse?

A data warehouse is a blend of technologies and components which allows the strategic use of data. It is a technique for collecting and managing data from varied sources to provide meaningful business insights.

It is electronic storage of a large amount of information by a business which is designed for query and analysis instead of transaction processing. It is a process of transforming data into information.

What is Data Lake?

A Data Lake is a storage repository that can store large amount of structured, semi-structured, and unstructured data. It is a place to store every type of data in its native format with no fixed limits on account size or file. It offers high data quantity to increase analytic performance and native integration.

Data Lake is like a large container which is very similar to real lake and rivers. Just like in a lake you have multiple tributaries coming in, a data lake has structured data, unstructured data, machine to machine, logs flowing through in real-time.

Data Warehouse Concept:

Data Warehouse stores data in files or folders which helps to organize and use the data to take strategic decisions. This storage system also gives a multi-dimensional view of atomic and summary data. The important functions which are needed to perform are:

  1. Data Extraction
  2. Data Cleaning
  3. Data Transformation
  4. Data Loading and Refreshing


  • Data Lake stores all data irrespective of the source and its structure whereas Data Warehouse stores data in quantitative metrics with their attributes.
  • Data Lake is a storage repository that stores huge structured, semi-structured and unstructured data while Data Warehouse is blending of technologies and component which allows the strategic use of data.
  • Data Lake defines the schema after data is stored whereas Data Warehouse defines the schema before data is stored.
  • Data Lake uses the ELT(Extract Load Transform) process while the Data Warehouse uses ETL(Extract Transform Load) process.
  • Data Lake is ideal for those who want in-depth analysis whereas Data Warehouse is ideal for operational users.

Data Lake Concept:

A Data Lake is a large size storage repository that holds a large amount of raw data in its original format until the time it is needed. Every data element in a Data lake is given a unique identifier and tagged with a set of extended metadata tags. It offers wide varieties of analytic capabilities.

Key Difference between the Data Lake and Data Warehouse

Here are key differences between the two data associated terms in the mentioned aspects:

Parameters Data Lake Data Warehouse
Storage In the data lake, all data is kept irrespective of the source and its structure. Data is kept in its raw form. It is only transformed when it is ready to be used. A data warehouse will consist of data that is extracted from transactional systems or data which consists of quantitative metrics with their attributes. The data is cleaned and transformed
History Big data technologies used in data lakes is relatively new. Data warehouse concept, unlike big data, had been used for decades.
Data Capturing Captures all kinds of data and structures, semi-structured and unstructured in their original form from source systems. Captures structured information and organizes them in schemas as defined for data warehouse purposes
Data Timeline Data lakes can retain all data. This includes not only the data that is in use but also data that it might use in the future. Also, data is kept for all time, to go back in time and do an analysis. In the data warehouse development process, significant time is spent on analyzing various data sources.
Users Data lake is ideal for the users who indulge in deep analysis. Such users include data scientists who need advanced analytical tools with capabilities such as predictive modeling and statistical analysis. The data warehouse is ideal for operational users because of being well structured, easy to use and understand.
Storage Costs Data storing in big data technologies are relatively inexpensive then storing data in a data warehouse. Storing data in Data warehouse is costlier and time-consuming.
Task Data lakes can contain all data and data types; it empowers users to access data prior the process of transformed, cleansed and structured. Data warehouses can provide insights into pre-defined questions for pre-defined data types.
Processing time Data lakes empower users to access data before it has been transformed, cleansed and structured. Thus, it allows users to get to their result more quickly compares to the traditional data warehouse. Data warehouses offer insights into pre-defined questions for pre-defined data types. So, any changes to the data warehouse needed more time.
Position of Schema Typically, the schema is defined after data is stored. This offers high agility and ease of data capture but requires work at the end of the process Typically schema is defined before data is stored. Requires work at the start of the process, but offers performance, security, and integration.
Data processing Data Lakes use of the ELT (Extract Load Transform) process. Data warehouse uses a traditional ETL (Extract Transform Load) process.
Complain Data is kept in its raw form. It is only transformed when it is ready to be used. The chief complaint against data warehouses is the inability, or the problem faced when trying to make change in in them.
Key Benefits They integrate different types of data to come up with entirely new questions as these users not likely to use data warehouses because they may need to go beyond its capabilities. Most users in an organization are operational. These type of users only care about reports and key performance metrics.