Trade-offs in Static and Dynamic Evaluation of Hierarchical Queries

Ahmet Kara, Milos Nikolic, Dan Olteanu, Haozhe Zhang

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

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.
Original languageEnglish
Article number11
Pages (from-to)1-50
Number of pages50
JournalLogical Methods in Computer Science
Issue number3
Publication statusPublished - 9 Aug 2023


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