Mining Conditional Cardinality Patterns for Data Warehouse Query Optimization

Recent advances in computing, communications, digital storage technologies, and high-throughput data-acquisition technologies, make it possible to gather and store incredible volumes of data. It creates unprecedented opportunities for large-scale knowledge discovery from huge database. Data mining (DM) technology has emerged as a means of performing this discovery. There are countless researchers working on designing efficient data mining techniques, methods, and algorithms. Many data mining methods and algorithms have been developed and applied in a lot of application fields [1]. Unfortunately, most data mining researchers pay much attention to technique problems for developing data mining models and methods, while little to basic issues of data mining [2]. In this talk, some basic issues of data mining are addressed. What is data mining? What is the product of a data mining process? What are we doing in a data mining process? What is the rule we should obey in a data mining process? Through analyzing existing data mining methods, and domain-driven (or user-driven) data mining models [3-5], we find that we should take a data mining process as a process of knowledge transformation. Based on this understanding of data mining, a conceptual data mining model of domain-oriented data-driven data mining (3DM) is proposed [2]. The relationship between traditional domain-driven (or user-driven) data mining models and our proposed 3DM model is also analyzed. Some domain-oriented data-driven data mining algorithms for mining such knowledge as default rule [6], decision tree [7], and concept lattice [8] from database are proposed. The experiment results for these algorithms are also shown to illustrate the efficiency and performance of the knowledge acquired by our 3DM data mining algorithms.

Deco is a comprehensive system for answering declarative queries posed over stored relational data together with data obtained on-demand from the crowd. In this paper we describe Deco's cost-based query optimizer, building on Deco's data model, query language, and query execution engine presented earlier. Deco's objective in query optimization is to find the best query plan to answer a query, in terms of estimated monetary cost. Deco's query semantics and plan execution strategies require several fundamental changes to traditional query optimization. Novel techniques incorporated into Deco's query optimizer include a cost model distinguishing between "free" existing data versus paid new data, a cardinality estimation algorithm coping with changes to the database state during query execution, and a plan enumeration algorithm maximizing reuse of common subplans in a setting that makes reuse challenging. We experimentally evaluate Deco's query optimizer, focusing on the accuracy of cost estimation and the efficiency of plan enumeration.

We study the problem of query optimization in federated relational database systems. The nature of federated databases explicitly decouples many aspects of the optimization process, often making it imperative for the optimizer to consult underlying data sources while doing cost-based optimization. This not only increases the cost of optimization, but also changes the trade-offs involved in the optimization process significantly. The dominant cost in the decoupled optimization process is the "cost of costing" that traditionally has been considered insignificant. The optimizer can only afford a few rounds of messages to the underlying data sources and hence the optimization techniques in this environment must be geared toward gathering all the required cost information with minimal communication. In this paper, we explore the design space for a query optimizer in this environment and demonstrate the need for decoupling various aspects of the optimization process. We present minimum-communication decoupled variants of various query optimization techniques, and discuss tradeoffs in their performance in this scenario. We have implemented these techniques in the Cohera federated database system and our experimental results, somewhat surprisingly, indicate that a simple two-phase optimization scheme performs fairly well as long as the physical database design is known to the optimizer, though more aggressive algorithms are required otherwise.

Database query optimization is a hard research problem. Exhaustive techniques are adequate for trivial instances only, while combinatorial optimization techniques are vulnerable to the peculiarities of specific instances. We propose a model based on genetic programming to address this problem, motivated by its robustness and efficiency in a wide area of search problems. We adapt the genetic programming paradigm to the requirements of the query optimization problem, showing that the nature of the problem makes genetic programming a particularly attractive approach to it.

S.70-79

This paper describes an approach to identify the state of a power system using Data Mining Algorithms. With the advent of Phasor Measurement Units (PMU), a huge amount of power system data is being stored day-to-day in the Phasor Data Collectors (PDCs). Knowledge discovery and machine learning techniques can make use of this data to extract valuable information and interesting patterns in these databases. In this paper, Symbolic Aggregate ApproXimation (SAX) is used to convert the time stamped phasor data from the PMUs into symbolic strings and Data Mining (DM) algorithms are used to predict the current state of a power system. Along with the state, the location and cause of disturbance is also identified in minimal time. The effectiveness of different DM algorithms for determining state of a power system is also shown using the measures of accuracy, precision and recall.

Preparing a data set for analysis is generally the most time consuming task in a data mining project, requiring many complex SQL queries, joining tables and aggregating columns. Existing SQL aggregations have limitations to prepare data sets because they return one column per aggregated group. In general, a significant manual effort is required to build data sets, where a horizontal layout is required. We propose simple, yet powerful, methods to generate SQL code to return aggregated columns in a horizontal tabular layout, returning a set of numbers instead of one number per row. This new class of functions is called horizontal aggregations. Horizontal aggregations build data sets with a horizontal denormalized layout (e.g. point-dimension, observation-variable, instance-feature), which is the standard layout required by most data mining algorithms. We propose three fundamental methods to evaluate horizontal aggregations: CASE: Exploiting the programming CASE construct; SPJ: Based on standard relational algebra operators (SPJ queries); PIVOT: Using the PIVOT operator, which is offered by some DBMSs. Experiments with large tables compare the proposed query evaluation methods. Our CASE method has similar speed to the PIVOT operator and it is much faster than the SPJ method. In general, the CASE and PIVOT methods exhibit linear scalability, where as the SPJ method does not. In a relational database, especially with normalized tables, a significant effort is required to prepare a summary data set that can be used as input for a data mining or statistical algorithm. Most algorithms require as input a data set with a horizontal layout, with several Records and one variable or dimension per column. That is the case with models like clustering, classification, regression and PCA; consult. Each research discipline uses different terminology to describe the data set. In data mining the common terms are point-dimension. Statistics literature generally uses observation-variable. Machine learning research uses instance-feature. This article introduces a new class of aggregate functions that can be used to build data sets in a horizontal layout (denormalized with aggregations), automating SQL query writing and extending SQL capabilities. We show evaluating horizontal aggregations is a challenging and interesting problem and we introduced alternative methods and optimizations for their efficient evaluation. II. MOTIVATION As mentioned above, building a suitable data set for data mining purposes is a time- consuming task. This task generally requires writing long SQL statements or customizing SQL Code if it is automatically generated by some tool. There are two main ingredients in such SQL code: joins and aggregations; we focus on the second one. The most widely- known aggregation is the sum of a column over groups of rows. Some other aggregations return the average, maximum, minimum or row count over groups of rows. There exist many aggregations functions and operators in SQL. Unfortunately, all these aggregations have limitations to build data sets for data mining purposes. The main reason is that, in general, data sets that are stored in a relational database (or a data warehouse) come

Since the very beginning of query processing in database systems, cost-based query optimization has been the essential strategy for effectively answering complex queries on large documents. XML documents can be efficiently stored and processed using native XML database management systems. Even though such systems can choose from a huge repertoire of join operators (e. g., Structural Joins and Holistic Twig Joins) and various index access operators to efficiently evaluate queries on XML documents, the development of full-fledged XML query optimizers is still in its infancy. Especially the evaluation of complex XQuery expressions using these operators is not well understood and needs further research. The extensible, rule-based, and cost-based XML query optimization framework proposed in this chapter, serves as a testbed for exploring how and whether well-known concepts from relational query optimization (e. g., join reordering) can be reused and which new techniques can make a significant contribution to speed-up query execution. Using the best practices and an appropriate cost model that will be developed using this framework, it can be turned into a robust cost-based XML query optimizer in the future.

Research in databases has played a vital role in developing information system technology and also the outcome of this research has been very successful resulting in great potential for industry. The database industry is generating billions of dollars of business annually. It has estimated that the database industry itself has generated $42 billion revenue in 2000 and this market is growing at 11% annually. In the software industry, it is second only to operating system software. The evolution of database systems started in late 60's when hierarchical and network data models were developed, but these models did not get much momentum because they were not suited for complex applications [9]. In early 70's, Ted Codd proposed a relational data model (for which he was awarded a Turing award) which became the backbone of developing database applications. Although this model was criticized by COBOL/CODASYL group people, it became very popular because of its simplicity. In late 70's and early 80's most of the research work was focused on developing fundamentals of relational database theory, query languages, transaction management and query optimization. In late 80's and early 90's, the database research community grew exponentially and made several breakthrough in many areas like object-oriented, active, deductive, and parallel and distributed databases. The research ideas in these areas have been implemented successfully in different database vendors' products. In early 90's, most of the businesses realize that their business is becoming very competitive and they need some sophisticated tools that can analyze their business data, customers profiles and product information so that they can improve their marketing strategy and management of organization. Data mining and data warehousing technology was developed for satisfying such needs [1].

Due to the ubiquity of spatial data applications and the large amounts of spatial data that these applications generate and process, there is a pressing need for scalable spatial query processing. In this paper, we present new techniques for spatial query processing and optimization in an in-memory and distributed setup to address scalability. More specifically, we introduce new techniques for handling query skew that commonly happens in practice, and minimizes communication costs accordingly. We propose a distributed query scheduler that uses a new cost model to minimize the cost of spatial query processing. The scheduler generates query execution plans that minimize the effect of query skew. The query scheduler utilizes new spatial indexing techniques based on bitmap filters to forward queries to the appropriate local nodes. Each local computation node is responsible for optimizing and selecting its best local query execution plan based on the indexes and the nature of the spatial queries in that node. All the proposed spatial query processing and optimization techniques are prototyped inside Spark, a distributed memory-based computation system. Our prototype system is termed LocationSpark. The experimental study is based on real datasets and demonstrates that LocationSpark can enhance distributed spatial query processing by up to an order of magnitude over existing in-memory and distributed spatial systems.

Contemporary e-commerce platforms face unprecedented challenges in managing and querying massive product datasets that demand real-time processing capabilities across petabyte-scale distributed systems. Traditional query optimization techniques, relying on static cost models and predetermined execution strategies, demonstrate significant limitations when applied to dynamic product discovery environments characterized by rapidly changing workload patterns and complex multi-dimensional search requirements. The integration of Reinforcement Learning into database query optimization represents a paradigmatic transformation toward adaptive systems capable of learning optimal decision-making strategies through continuous environmental interaction and performance feedback. Reinforcement Learning-based optimization frameworks address critical challenges in large-scale product discovery through intelligent indexing strategies, dynamic query reformulation techniques, and adaptive resource allocation mechanisms. These systems employ sophisticated neural network architectures, including Deep Q-Networks, Actor-Critic methods, and Multi-Agent frameworks that enable real-time adaptation to evolving data characteristics and system conditions. The implementation of such systems requires comprehensive architectural considerations encompassing distributed learning mechanisms, privacy-preserving techniques, and robust integration frameworks that maintain compatibility with existing database infrastructures while delivering enhanced performance capabilities across diverse workload scenarios.

<!-- /* Font Definitions */ @font-face {font-family:??; panose-1:2 1 6 0 3 1 1 1 1 1; mso-font-alt:SimSun; mso-font-charset:134; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:3 135135232 16 0 262145 0;} @font-face {font-family:

Using the contextual language model BERT for multi-criteria classification of scientific articles.

In this paper we study precedence constrained scheduling problems, where the tasks can only be executed on a specified subset of the machines. Each machine has a loading time that is incurred only for the first task that is scheduled on the machine in a particular run. This basic scheduling problem arises in the context of machining on numerically controlled machines, query optimization in databases, and in other artificial intelligence applications. We give the first non-trivial approximation algorithm for this problem. We also prove non-trivial lower bounds on best possible approximation ratios for these problems. These improve on the non-approximability results that are implied by the non-approximability results for the shortest common supersequence problem. We use the same algorithmic technique to obtain approximation algorithms for a problem arising in the context of code generation for parallel machines, and for the weighted shortest common supersequence problem.

Use of machine learning (ML) and data mining (DM) algorithms has surfaced more often in the recent years for disease risk prediction problems in the healthcare communities. Several traditional feature selection models are combined with the DM and ML algorithms to improve accuracy of the disease risk prediction. In this study, a new Bio-inspired Ensemble Feature Selection (BEFS) model is introduced which is applied with the DM and ML algorithms. In the BEFS model, the most relevant and highly contributing features in the prediction are determined with a bio-inspired algorithm i.e., genetic algorithm, and an ensemble algorithm i.e., random forest algorithm. These important features obtained from the proposed model are then combined in various combinations and applied with the DM and ML algorithms, here logistic regression (LR) and random forest (RF), and the results obtained are promising. The experiment is executed using the famous ML language R. To accomplish this objective, the Breast Cancer Wisconsin (Diagnostic) dataset of UCI (University of California, Irvine) ML repository is utilized. In the experimental outcomes, the highest accuracy attained with the BEFS model is 96.49%, the AUC (Area Under Curve) achieved is 96%, and the sensitivity is 98.11%. These results, which greatly improve the disease risk prediction, are higher than several other existing works, while utilizing only six most relevant features out of the thirty two features of the dataset.