Transactions on the multiversion B+-tree

  • Authors:

  • Tuukka Haapasalo;Ibrahim Jaluta;Bernhard Seeger;Seppo Sippu;Eljas Soisalon-Soininen

  • Affiliations:

  • Helsinki University of Technology, Finland;Helsinki University of Technology, Finland;Philipps-University Marburg, Marburg, Germany;University of Helsinki, Helsinki, Finland;Helsinki University of Technology, Finland

  • Venue:
  • Proceedings of the 12th International Conference on Extending Database Technology: Advances in Database Technology
  • Year:
  • 2009

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Abstract

The multiversion B+-tree (MVBT) by Becker et al. assumes a single-data-item update model in which each new version created for a data item is given a timestamp that is unique across the entire MVBT. In this paper, we extend the MVBT model with multi-action transactions such that all (final) data-item versions created by a transaction are given the same timestamp. We show that the MVBT algorithms can be modified to work in a setting in which multiple readonly transactions and a single updating transaction operate concurrently in snapshot isolation on the MVBT, without compromising the asymptotically optimal time complexity of key inserts, key deletes, and key-range scans on any version. The structural consistency and balance of the MVBT is guaranteed by short-duration latching of pages, redo-only logging of structure modifications (version splits, key splits and page merges), and redo-undo logging of key insertions and deletions. The redo pass of our ARIES-based restart-recovery algorithm always produces a structurally consistent and balanced MVBT on which any undo action by a backward-rolling updating transaction can be performed logically if a physical undo is not possible. The standard steal-and-no-force buffering policy is assumed.