Data classification includes tracking classification of columns of data into data classes of a collection of classes available for classifying the columns, obtaining a target column of data, of a target dataset, to be classified into a data class of the collection of candidate classes, and classifying the target column of data into a data class of the collection of classes based on historical data classification characteristics provided by the tracking. The classifying includes selecting a group of candidate data classes of the collection of classes to compare to value(s) of the target column, the selecting excludes at least some candidate data classes of the collection from comparison to the value(s), and establishing a priority between the candidate data classes of the group of candidate classes in comparing the value(s) of the target column of data to the selected group of candidate classes.