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LATIN
2010
Springer

Lightweight Data Indexing and Compression in External Memory

13 years 5 months ago
Lightweight Data Indexing and Compression in External Memory
In this paper we describe algorithms for computing the BWT and for building (compressed) indexes in external memory. The innovative feature of our algorithms is that they are lightweight in the sense that, for an input of size n, they use only n bits of disk working space while all previous approaches use Θ(n log n) bits of disk working space. Moreover, our algorithms access disk data only via sequential scans, thus they take full advantage of modern disk features that make sequential disk accesses much faster than random accesses. We also present a scan-based algorithm for inverting the BWT that uses Θ(n) bits of working space, and a lightweight internal-memory algorithm for computing the BWT which is the fastest in the literature when the available working space is o(n) bits. Finally, we prove lower bounds on the complexity of computing and inverting the BWT via sequential scans in terms of the classic product: internal-memory space × number of passes over the disk data.
Paolo Ferragina, Travis Gagie, Giovanni Manzini
Added 12 Oct 2010
Updated 12 Oct 2010
Type Conference
Year 2010
Where LATIN
Authors Paolo Ferragina, Travis Gagie, Giovanni Manzini
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