Ahmet Kara ; Milos Nikolic ; Dan Olteanu ; Haozhe Zhang - Trade-offs in Static and Dynamic Evaluation of Hierarchical Queries

lmcs:10035 - Logical Methods in Computer Science, August 9, 2023, Volume 19, Issue 3 - https://doi.org/10.46298/lmcs-19(3:11)2023
Trade-offs in Static and Dynamic Evaluation of Hierarchical QueriesArticle

Authors: Ahmet Kara ; Milos Nikolic ; Dan Olteanu ; Haozhe Zhang

    We investigate trade-offs in static and dynamic evaluation of hierarchical queries with arbitrary free variables. In the static setting, the trade-off is between the time to partially compute the query result and the delay needed to enumerate its tuples. In the dynamic setting, we additionally consider the time needed to update the query result under single-tuple inserts or deletes to the database. Our approach observes the degree of values in the database and uses different computation and maintenance strategies for high-degree (heavy) and low-degree (light) values. For the latter it partially computes the result, while for the former it computes enough information to allow for on-the-fly enumeration. We define the preprocessing time, the update time, and the enumeration delay as functions of the light/heavy threshold. By appropriately choosing this threshold, our approach recovers a number of prior results when restricted to hierarchical queries. We show that for a restricted class of hierarchical queries, our approach achieves worst-case optimal update time and enumeration delay conditioned on the Online Matrix-Vector Multiplication Conjecture.

    Volume: Volume 19, Issue 3
    Published on: August 9, 2023
    Accepted on: June 13, 2023
    Submitted on: September 13, 2022
    Keywords: Computer Science - Databases,Computer Science - Logic in Computer Science


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