Details

Autor(en) / Beteiligte

• Wyss, Catharine M.
• Robertson, Edward L.

Titel

A formal characterization of PIVOT/UNPIVOT

Ist Teil von

• Conference on Information and Knowledge Management: Proceedings of the 14th ACM international conference on Information and knowledge management; 31 Oct.-05 Nov. 2005, 2005, p.602-608

Ort / Verlag

New York, NY, USA: ACM

Erscheinungsjahr

2005

Quelle

ACM Digital Library

Beschreibungen/Notizen

• PIVOT is an important relational operation that allows data in rows to be exchanged for columns. Although most current relational database management systems support PIVOT-type operations, to date a purely formal, algebraic characterization of PIVOT has been lacking. In this paper, we present a characterization in terms of extended relational algebra operators τ (transpose), Π (drop projection), and μ (unique optimal tuple merge). This enables us to (1) draw parallels with PIVOT and existing operators employed in Dynamic Data Mapping Systems (DDMS), (2) formally characterize invertible PIVOT instances, and (3) provide complexity results for PIVOT-type operations. These contributions are an important part of ongoing work on formal models for relational OLAP.