Storage Solutions for Big Data Systems: A Qualitative Study and Comparison

Big data systems development is full of challenges in view of the variety of application areas and domains that this technology promises to serve. Typically, fundamental design decisions involved in big data systems design include choosing appropriate storage and computing infrastructures. In this age of heterogeneous systems that integrate different technologies for optimized solution to a specific real world problem, big data system are not an exception to any such rule. As far as the storage aspect of any big data system is concerned, the primary facet in this regard is a storage infrastructure and NoSQL seems to be the right technology that fulfills its requirements. However, every big data application has variable data characteristics and thus, the corresponding data fits into a different data model. This paper presents feature and use case analysis and comparison of the four main data models namely document oriented, key value, graph and wide column. Moreover, a feature analysis of 80 NoSQL solutions has been provided, elaborating on the criteria and points that a developer must consider while making a possible choice. Typically, big data storage needs to communicate with the execution engine and other processing and visualization technologies to create a comprehensive solution. This brings forth second facet of big data storage, big data file formats, into picture. The second half of the research paper compares the advantages, shortcomings and possible use cases of available big data file formats for Hadoop, which is the foundation for most big data computing technologies. Decentralized storage and blockchain are seen as the next generation of big data storage and its challenges and future prospects have also been discussed

LogBase: A Scalable Log-structured Database System in the Cloud

Numerous applications such as financial transactions (e.g., stock trading) are write-heavy in nature. The shift from reads to writes in web applications has also been accelerating in recent years. Write-ahead-logging is a common approach for providing recovery capability while improving performance in most storage systems. However, the separation of log and application data incurs write overheads observed in write-heavy environments and hence adversely affects the write throughput and recovery time in the system. In this paper, we introduce LogBase - a scalable log-structured database system that adopts log-only storage for removing the write bottleneck and supporting fast system recovery. LogBase is designed to be dynamically deployed on commodity clusters to take advantage of elastic scaling property of cloud environments. LogBase provides in-memory multiversion indexes for supporting efficient access to data maintained in the log. LogBase also supports transactions that bundle read and write operations spanning across multiple records. We implemented the proposed system and compared it with HBase and a disk-based log-structured record-oriented system modeled after RAMCloud. The experimental results show that LogBase is able to provide sustained write throughput, efficient data access out of the cache, and effective system recovery.Comment: VLDB201

The Evolution of Cloud Data Architectures: Storage, Compute, and Migration

Recent advances in data architectures have shifted from on-premises to the cloud. However, new challenges emerge as data explosion continues to expand at an exponential rate. As a result, my Ph.D. research focuses on addressing the following challenges. First, cloud data-warehouses such as Snowflake, BigQuery, and Redshift often rely on storage systems such as distributed file systems or object stores to store massive amounts of data. The growth of data volumes is accompanied by an increase in the number of objects stored and the amount of metadata such systems must manage. By treating metadata management similar to data management, we built FileScale, an HDFS-based file system that replaces metadata management in HDFS with a three-tiered distributed architecture that incorporates a high throughput, distributed main-memory database system at the lowest layer, along with distributed caching and routing functionality above it. FileScale performs comparably to the single-machine architecture at a small scale, while enabling linear scalability as the file system metadata increases. Second, Function as a Service, or FaaS, is a new type of cloud-computing service that executes code in response to events without the complex infrastructure typically associated with building and launching microservices applications. FaaS offers cloud functions with millisecond billing granularity to be scaled automatically, independently, and instantaneously as needed. We built Flock, the first practical cloud-native SQL query engine that supports event stream processing on FaaS with heterogeneous hardware (x86 and Arm) with the ability to shuffle and aggregate data without requiring a centralized coordinator or remote storage such as Amazon S3. This architecture is more cost-effective than traditional systems, especially for dynamic workloads and continuous queries. Third, Software as a Service, or SaaS, is a method of software product delivery to end-users over the internet and via pay-as-you-go pricing in which the software is centrally hosted and managed by the cloud service provider. Continuous Deployment (CD) in SaaS, an aspect of DevOps, is the increasingly popular practice of frequent, automated deployment of software changes. To realize the benefits of CD, it must be straightforward to deploy updates to both front-end code and the database, even when the database’s schema has changed. Unfortunately, this is where current practices run into difficulty. So we built BullFrog, a PostgreSQL extension that is the first system to use lazy schema migration to support single-step, online schema evolution without downtime, which achieves efficient, exactly-once physical migration of data under contention

A study of three paradigms for storing geospatial data: distributed-cloud model, relational database, and indexed flat file

Geographic Information Systems (GIS) and related applications of geospatial data were once a small software niche; today nearly all Internet and mobile users utilize some sort of mapping or location-aware software. This widespread use reaches beyond mere consumption of geodata; projects like OpenStreetMap (OSM) represent a new source of geodata production, sometimes dubbed “Volunteered Geographic Information.” The volume of geodata produced and the user demand for geodata will surely continue to grow, so the storage and query techniques for geospatial data must evolve accordingly. This thesis compares three paradigms for systems that manage vector data. Over the past few decades these methodologies have fallen in and out of favor. Today, some are considered new and experimental (distributed), others nearly forgotten (flat file), and others are the workhorse of present-day GIS (relational database). Each is well-suited to some use cases, and poorly-suited to others. This thesis investigates exemplars of each paradigm

Augmenting data warehousing architectures with hadoop

Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Information Systems and Technologies ManagementAs the volume of available data increases exponentially, traditional data warehouses struggle to transform this data into actionable knowledge. Data strategies that include the creation and maintenance of data warehouses have a lot to gain by incorporating technologies from the Big Data’s spectrum. Hadoop, as a transformation tool, can add a theoretical infinite dimension of data processing, feeding transformed information into traditional data warehouses that ultimately will retain their value as central components in organizations’ decision support systems. This study explores the potentialities of Hadoop as a data transformation tool in the setting of a traditional data warehouse environment. Hadoop’s execution model, which is oriented for distributed parallel processing, offers great capabilities when the amounts of data to be processed require the infrastructure to expand. Horizontal scalability, which is a key aspect in a Hadoop cluster, will allow for proportional growth in processing power as the volume of data increases. Through the use of a Hive on Tez, in a Hadoop cluster, this study transforms television viewing events, extracted from Ericsson’s Mediaroom Internet Protocol Television infrastructure, into pertinent audience metrics, like Rating, Reach and Share. These measurements are then made available in a traditional data warehouse, supported by a traditional Relational Database Management System, where they are presented through a set of reports. The main contribution of this research is a proposed augmented data warehouse architecture where the traditional ETL layer is replaced by a Hadoop cluster, running Hive on Tez, with the purpose of performing the heaviest transformations that convert raw data into actionable information. Through a typification of the SQL statements, responsible for the data transformation processes, we were able to understand that Hadoop, and its distributed processing model, delivers outstanding performance results associated with the analytical layer, namely in the aggregation of large data sets. Ultimately, we demonstrate, empirically, the performance gains that can be extracted from Hadoop, in comparison to an RDBMS, regarding speed, storage usage and scalability potential, and suggest how this can be used to evolve data warehouses into the age of Big Data

Survey of NoSQL Database Engines for Big Data

Cloud computing is a paradigm shift that provides computing over Internet. With growing outreach of Internet in the lives of people, everyday large volume of data is generated from different sources such as cellphones, electronic gadgets, e-commerce transactions, social media, and sensors. Eventually, the size of generated data is so large that it is also referred as Big Data. Companies harvesting business opportunities in digital world need to invest their budget and time to scale their IT infrastructure for the expansion of their businesses. The traditional relational databases have limitations in scaling for large Internet scale distributed systems. To store rapidly expanding high volume Big Data efficiently, NoSQL data stores have been developed as an alternative solution to the relational databases. The purpose of this thesis is to provide a holistic overview of different NoSQL data stores. We cover different fundamental principles supporting the NoSQL data store development. Many NoSQL data stores have specific and exclusive features and properties. They also differ in their architecture, data model, storage system, and fault tolerance abilities. This thesis describes different aspects of few NoSQL data stores in detail. The thesis also covers the experiments to evaluate and compare the performance of different NoSQL data stores on a distributed cluster. In the scope of this thesis, HBase, Cassandra, MongoDB, and Riak are four NoSQL data stores selected for the benchmarking experiments