Data Consistency

Data consistency is a feature through that the RDBMS ensures what you see or understand about the state of the data is what is really the state in the database. This denotes you get a consistent view of the database from the RDBMS every time you query the database so which you can go ahead with processing the data.

Oracle 8 gives foolproof data consistency through providing two kinds of data consistency that are one at the statement level and other at the transaction level. This is due to the fact which since the consistent  view  of  data  is  needed  for  two  distinct  types  of  operations,  that are one  to  take  a decision and other to effect a modification based on the view. Consequently, the first operation is just a query and is more of a DSS nature and the second are a transaction where a query and following changes together make sense and this is of OLTP nature.

Statement level read reliable view of data is consistent in during the execution time and the next execution of the similar query might give a variant view of data.Transaction level read consistent view of data is consistent for the overall transaction. This means, the view of data is the similar for one or more execution of the query inside the transaction. Once the transaction finished then the view of the data should change.