The subject invention relates to systems and methods that perform consistency checks of user defined type (UDT) fragments utilizing a stream of data without wholesale copying of the data. Streaming consistency checks facilitate discovering invalid fragments as soon as possible such that the entire UDT fragment does not have to be read, stored, analyzed, etc. Additionally, a UDT fragment can be evaluated without being completely materialized; thus, systems and/or methods employing the subject invention can yield improved performance as compared to conventional techniques by reducing required resources and enabling faster detection of invalid structures.