ORA-04091: table is mutating, trigger/function may not see it

The Mutating table error is a well-known problem encountered in development; most developers have come across this error.


ORA-04091: table is mutating,
trigger/function may not see it



The basic reason for this error is the way Oracle manages a read consistent view of data. The error is encountered when a row-level trigger accesses the same table on which it is based, while executing. The table is said to be mutating. Mutation will not occur if a single record is inserted in the table (using VALUES clause). If bulk insertion is done or data is inserted from another table mutation will occur.

http://www.dbasupport.com/oracle/ora9i/mutationError.shtml