Dan Olteanu
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View article: Advancing Fact Attribution for Query Answering: Aggregate Queries and Novel Algorithms
Advancing Fact Attribution for Query Answering: Aggregate Queries and Novel Algorithms Open
In this paper, we introduce a novel approach to computing the contribution of input tuples to the result of the query, quantified by the Banzhaf and Shapley values. In contrast to prior algorithmic work that focuses on Select-Project-Join-…
View article: Using Process Calculus for Optimizing Data and Computation Sharing in Complex Stateful Parallel Computations
Using Process Calculus for Optimizing Data and Computation Sharing in Complex Stateful Parallel Computations Open
We propose novel techniques that exploit data and computation sharing to improve the performance of complex stateful parallel computations, like agent-based simulations. Parallel computations are translated into behavioral equations, a nov…
View article: <scp>LpBound</scp> : Pessimistic Cardinality Estimation Using ℓ <sub>p</sub> -Norms of Degree Sequences
<span>LpBound</span> : Pessimistic Cardinality Estimation Using ℓ <sub>p</sub> -Norms of Degree Sequences Open
Cardinality estimation is the problem of estimating the size of the output of a query, without actually evaluating the query. The cardinality estimator is a critical piece of a query optimizer, and is often the main culprit when the optimi…
View article: Conjunctive Queries with Free Access Patterns under Updates
Conjunctive Queries with Free Access Patterns under Updates Open
We study the problem of answering conjunctive queries with free access patterns (CQAPs) under updates. A free access pattern is a partition of the free variables of the query into input and output. The query returns tuples over the output …
View article: Output-Sensitive Evaluation of Regular Path Queries
Output-Sensitive Evaluation of Regular Path Queries Open
We study the classical evaluation problem for regular path queries: Given an edge-labeled graph and a regular path query, compute the set of pairs of vertices that are connected by paths that match the query. The Product Graph (PG) is the …
View article: Information Theory Strikes Back: New Development in the Theory of Cardinality Estimation
Information Theory Strikes Back: New Development in the Theory of Cardinality Estimation Open
Estimating the cardinality of the output of a query is a fundamental problem in database query processing. In this article, we overview a recently published contribution that casts the cardinality estimation problem as linear optimization …
View article: LpBound: Pessimistic Cardinality Estimation using $\ell_p$-Norms of Degree Sequences
LpBound: Pessimistic Cardinality Estimation using $\ell_p$-Norms of Degree Sequences Open
Cardinality estimation is the problem of estimating the size of the output of a query, without actually evaluating the query. The cardinality estimator is a critical piece of a query optimizer, and is often the main culprit when the optimi…
View article: Output-Sensitive Evaluation of Regular Path Queries
Output-Sensitive Evaluation of Regular Path Queries Open
We study the classical evaluation problem for regular path queries: Given an edge-labeled graph and a regular path query, compute the set of pairs of vertices that are connected by paths that match the query. The Product Graph (PG) is the …
View article: Pessimistic Cardinality Estimation
Pessimistic Cardinality Estimation Open
Cardinality Estimation is to estimate the size of the output of a query without computing it, by using only statistics on the input relations. Existing estimators try to return an unbiased estimate of the cardinality: this is notoriously d…
View article: Insert-Only versus Insert-Delete in Dynamic Query Evaluation
Insert-Only versus Insert-Delete in Dynamic Query Evaluation Open
We study the dynamic query evaluation problem: Given a full conjunctive query Q and a sequence of updates to the input database, we construct a data structure that supports constant-delay enumeration of the tuples in the query output after…
View article: QirK: Question Answering via Intermediate Representation on Knowledge Graphs
QirK: Question Answering via Intermediate Representation on Knowledge Graphs Open
We demonstrate QirK, a system for answering natural language questions on Knowledge Graphs (KG). QirK can answer structurally complex questions that are still beyond the reach of emerging Large Language Models (LLMs). It does so using a un…
View article: Banzhaf Values for Facts in Query Answering
Banzhaf Values for Facts in Query Answering Open
Quantifying the contribution of database facts to query answers has been studied as means of explanation. The Banzhaf value, originally developed in Game Theory, is a natural measure of fact contribution, yet its efficient computation for …
View article: Recent Increments in Incremental View Maintenance
Recent Increments in Incremental View Maintenance Open
We overview recent progress on the longstanding problem of incremental view maintenance (IVM), with a focus on the fine-grained complexity and optimality of IVM for classes of conjunctive queries. This theoretical progress is accompanied b…
View article: From Shapley Value to Model Counting and Back
From Shapley Value to Model Counting and Back Open
In this paper we investigate the problem of quantifying the contribution of each variable to the satisfying assignments of a Boolean function based on the Shapley value. Our main result is a polynomial-time equivalence between computing Sh…
View article: Join Size Bounds using l <sub>p</sub> -Norms on Degree Sequences
Join Size Bounds using l <sub>p</sub> -Norms on Degree Sequences Open
Estimating the output size of a query is a fundamental yet longstanding problem in database query processing. Traditional cardinality estimators used by database systems can routinely underestimate the true output size by orders of magnitu…
View article: Tractable Conjunctive Queries over Static and Dynamic Relations
Tractable Conjunctive Queries over Static and Dynamic Relations Open
We investigate the evaluation of conjunctive queries over static and dynamic relations. While static relations are given as input and do not change, dynamic relations are subject to inserts and deletes. We characterise syntactically three …
View article: Insert-Only versus Insert-Delete in Dynamic Query Evaluation
Insert-Only versus Insert-Delete in Dynamic Query Evaluation Open
We study the dynamic query evaluation problem: Given a full conjunctive query Q and a sequence of updates to the input database, we construct a data structure that supports constant-delay enumeration of the tuples in the query output after…
View article: Givens rotations for QR decomposition, SVD and PCA over database joins
Givens rotations for QR decomposition, SVD and PCA over database joins Open
This article introduces FiGaRo , an algorithm for computing the upper-triangular matrix in the QR decomposition of the matrix defined by the natural join over relational data. FiGaRo ’s main novelty is that it pushes the QR decomposition p…
View article: Banzhaf Values for Facts in Query Answering
Banzhaf Values for Facts in Query Answering Open
Quantifying the contribution of database facts to query answers has been studied as means of explanation. The Banzhaf value, originally developed in Game Theory, is a natural measure of fact contribution, yet its efficient computation for …
View article: Trade-offs in Static and Dynamic Evaluation of Hierarchical Queries
Trade-offs in Static and Dynamic Evaluation of Hierarchical Queries Open
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 enumer…
View article: ADOPT: Adaptively Optimizing Attribute Orders for Worst-Case Optimal Join Algorithms via Reinforcement Learning
ADOPT: Adaptively Optimizing Attribute Orders for Worst-Case Optimal Join Algorithms via Reinforcement Learning Open
The performance of worst-case optimal join algorithms depends on the order in which the join attributes are processed. Selecting good orders before query execution is hard, due to the large space of possible orders and unreliable execution…
View article: From Shapley Value to Model Counting and Back
From Shapley Value to Model Counting and Back Open
In this paper we investigate the problem of quantifying the contribution of each variable to the satisfying assignments of a Boolean function based on the Shapley value. Our main result is a polynomial-time equivalence between computing Sh…
View article: Join Size Bounds using Lp-Norms on Degree Sequences
Join Size Bounds using Lp-Norms on Degree Sequences Open
Estimating the output size of a query is a fundamental yet longstanding problem in database query processing. Traditional cardinality estimators used by database systems can routinely underestimate the true output size by orders of magnitu…
View article: CHORUS: Foundation Models for Unified Data Discovery and Exploration
CHORUS: Foundation Models for Unified Data Discovery and Exploration Open
We apply foundation models to data discovery and exploration tasks. Foundation models include large language models (LLMs) that show promising performance on a range of diverse tasks unrelated to their training. We show that these models a…
View article: F-IVM: Analytics over Relational Databases under Updates
F-IVM: Analytics over Relational Databases under Updates Open
This article describes F-IVM, a unified approach for maintaining analytics over changing relational data. We exemplify its versatility in four disciplines: processing queries with group-by aggregates and joins; learning linear regression m…
View article: Conjunctive Queries with Free Access Patterns under Updates
Conjunctive Queries with Free Access Patterns under Updates Open
We study the problem of answering conjunctive queries with free access patterns (CQAPs) under updates. A free access pattern is a partition of the free variables of the query into input and output. The query returns tuples over the output …
View article: The Complexity of Boolean Conjunctive Queries with Intersection Joins
The Complexity of Boolean Conjunctive Queries with Intersection Joins Open
Intersection joins over interval data are relevant in spatial and temporal data settings. A set of intervals join if their intersection is non-empty. In case of point intervals, the intersection join becomes the standard equality join.
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View article: Givens QR Decomposition over Relational Databases
Givens QR Decomposition over Relational Databases Open
This paper introduces Figaro, an algorithm for computing the upper-triangular matrix in the QR decomposition of the matrix defined by the natural join over a relational database. The QR decomposition lies at the core of many linear algebra…