Problems of Data Warehousing
The problems associated with developing and managing a data warehousing are as follows:
Underestimation of resources of data loading
Some times we underestimate the time required to extract, clean, and load the data into the warehouse. It may take the significant proportion of the total development time, although some tools are there which are used to reduce the time and effort spent on this process.
Hidden problems with source systems
Some times hidden .problems associated with the source systems feeding the data warehouse may be identified after years of being undetected. For example, when entering the details of a new property, certain fields may allow nulls which may result in staff entering incomplete property data, even when available and applicable.
Required data not captured
In some cases the required data is not captured by the source systems which may be very important for the data warehouse purpose. For example the date of registration for the property may be not used in source system but it may be very important analysis purpose.
Increased end-user demands
After satisfying some of end-users queries, requests for support from staff may increase rather than decrease. This is caused by an increasing awareness of the users on the capabilities and value of the data warehouse. Another reason for increasing demands is that once a data warehouse is online, it is often the case that the number of users and queries increase together with requests for answers to more and more complex queries.
Data homogenization
The concept of data warehouse deals with similarity of data formats between different data sources. Thus, results in to lose of some important value of the data.
High demand for resources
The data warehouse requires large amounts of data.
Data ownership
Data warehousing may change the attitude of end-users to the ownership of data. Sensitive data that owned by one department has to be loaded in data warehouse for decision making purpose. But some time it results in to reluctance of that department because it may hesitate to share it with others.
High maintenance
Data warehouses are high maintenance systems. Any reorganization· of the business processes and the source systems may affect the data warehouse and it results high maintenance cost.
Long-duration projects
The building of a warehouse can take up to three years, which is why some organizations are reluctant in investigating in to data warehouse. Some only the historical data of a particular department is captured in the data warehouse resulting data marts. Data marts support only the requirements of a particular department and limited the functionality to that department or area only.
Complexity of integration
The most important area for the management of a data warehouse is the integration capabilities. An organization must spend a significant amount of time determining how well the various different data warehousing tools can be integrated into the overall solution that is needed. This can be a very difficult task, as there are a number of tools for every operation of the data warehouse.
