1. A method for identifying a root cause of a data quality issue in a data flow comprising: applying periodically a data validation rule to data transformed through a data processing system, wherein the data validation rule applies aspects selected from a group consisting of data value range, specific data values, and relationship with other data entries; responsive to detecting a violation of the data validation rule, identifying a portion of the transformed data for lineage assessment; identifying a current node in a lineage graph; determining, for each of a plurality of other nodes in the lineage graph, whether the data transformed through the data processing system has been moved from a respective node in the lineage graph, or the data transformed through the data processing system has been transformed at the respective node; creating exception records that record exception properties of the data transformed through the data processing system, wherein the created exception records are created in response to execution of the data validation rule producing an exception; examining the identified transformed data iteratively upstream at a previous transformation node from the current node in the lineage graph where the identified transformed data is moved from or transformed from the previous transformation node, until the method detects a node where the violation of the data validation rule can't be reproduced; selecting a plurality of the exception records as sample records; determining whether the current node or the previous transformation node contains the violation of the data violation rule; and determining that a root cause of a data quality issue was created between the current node and the previous transformation node in response to the previous transformation node having equal or less occurrences of the violation of the data violation rule than the current node.