Rathish Das’s scientific contributions

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Publications (2)


Figure 1 B ϵ -tree.
External-Memory Dictionaries with Worst-Case Update Cost
  • Article
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December 2022

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29 Reads

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1 Citation

Rathish Das

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John Iacono

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The Bϵ-tree [Brodal and Fagerberg 2003] is a simple I/O-efficient external-memory-model data structure that supports updates orders of magnitude faster than B-tree with a query performance comparable to the B-tree: for any positive constant ϵ < 1 insertions and deletions take O(B11-ϵ logB N) time (rather than O(logB N) time for the classic B-tree), queries take O(logB N) time and range queries returning k items take O(logB N + Bk) time. Although the Bϵ-tree has an optimal update/query tradeoff, the runtimes are amortized. Another structure, the write-optimized skip list, introduced by Bender et al. [PODS 2017], has the same performance as the Bϵ-tree but with runtimes that are randomized rather than amortized. In this paper, we present a variant of the Bϵ-tree with deterministic worst-case running times that are identical to the original’s amortized running times.

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External-memory dictionaries with worst-case update cost

November 2022

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5 Reads

The BϵB^{\epsilon}-tree [Brodal and Fagerberg 2003] is a simple I/O-efficient external-memory-model data structure that supports updates orders of magnitude faster than B-tree with a query performance comparable to the B-tree: for any positive constant ϵ<1\epsilon<1 insertions and deletions take O(1B1ϵlogBN)O(\frac{1}{B^{1-\epsilon}}\log_{B}N) time (rather than O(logBN)O(\log_BN) time for the classic B-tree), queries take O(logBN)O(\log_BN) time and range queries returning k items take O(logBN+kB)O(\log_BN+\frac{k}{B}) time. Although the BϵB^{\epsilon}-tree has an optimal update/query tradeoff, the runtimes are amortized. Another structure, the write-optimized skip list, introduced by Bender et al. [PODS 2017], has the same performance as the BϵB^{\epsilon}-tree but with runtimes that are randomized rather than amortized. In this paper, we present a variant of the BϵB^{\epsilon}-tree with deterministic worst-case running times that are identical to the original's amortized running times.

Citations (1)


... ‡ assumes M = Ω(B log B N ); and * assumes M = Ω B 1−ε log 2 (maxv Nv) . For both queries and updates in [7,15], we include the multiplicative dependency on 1 ε (that can be omitted when treating ε as a constant), allowing, for example, setting ε = 1 log 2 B . All ephemeral results use space linear in N and all partial persistence results use space linear in the total number of updates. ...

Reference:

Buffered Partially-Persistent External-Memory Search Trees
External-Memory Dictionaries with Worst-Case Update Cost