Read Committed is the default isolation level in Daffodil DB. When a transaction runs on this isolation level, a SELECT query is able to extract the data committed before the query began and never gets a view of either uncommitted or changes committed during query execution by concurrent transactions. It is to be noted that two successive SELECT statements can see different data, even though they are within a single transaction, when other transactions commit changes during execution of the first SELECT statement. The partial transaction isolation provided by Read Committed level is adequate for many applications, and this level is fast and simple to use. However, for applications that do complex queries and updates, it may be necessary to guarantee a more rigorous and consistent view of the database.