Where Provenance in Database Storage

Abstract

Where provenance is a relationship between a data item and the location from which this data was copied. In a DBMS, a typical use of where provenance is in establishing a copy-by-address relationship between the output of a query and the particular data value(s) that originated it. Normal DBMS operations create a variety of auxiliary copies of the data (e.g., indexes, MVs, cached copies). These copies exist over time with relationships that evolve continuously – (A) indexes maintain the copy with a reference to the origin value, (B) MVs maintain the copy without a reference to the source table, (C) cached copies are created once and are never maintained. A query may be answered from any of these auxiliary copies; however, this where provenance is not computed or maintained. In this paper, we describe sources from which forensic analysis of storage can derive where provenance of table data. We also argue that this computed where provenance can be useful (and perhaps necessary) for accurate forensic reports and evidence from maliciously altered databases or validation of corrupted DBMS storage.