Navigating Data Management: Warehouses, Lakes and Lakehouses

    Leonid Chashnikov
    Leonid Chashnikov
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    In today’s dynamic data management landscape, the terminology and concepts related to data storage and processing have become more intricate. Businesses face a significant challenge in efficiently handling the influx of data from diverse sources. In this article, I aim to unravel various approaches to data management, offering examples of tools for each concept and providing a roadmap of the modern data management landscape.

    Table of Contents

    Database: The Foundation

    Databases have long served as the cornerstone of data management, providing structured repositories for efficient data storage, organization, and retrieval. They can be broadly categorized into relational databases and NoSQL databases, each tailored to specific data requirements and use cases. SQL solutions typically involve normalized schemas and cater to OLTP use cases, while some NoSQL databases excel with denormalized data.

    Key features of databases include:

    • Structured data storage. Databases excel at handling structured data, ensuring data integrity through predefined schemas.
    • Efficient row-level queries. Databases are optimized for row querying, and when the query is “correct”, the database can retrieve single or several records very quickly by utilizing indices.
    • Simple deletion and updates. Databases efficiently handle updating or deleting a single row.

    While databases are robust for managing structured data, they may face limitations with unstructured or semi-structured data and aren’t well-suited for analytical queries that involve reading millions or billions of rows at once. This limitation spurred the development of more specialized solutions like data warehouses and data lakes, which we’ll explore in the following sections.

    For classic SQL options, PostgreSQL and MySQL are noteworthy, and on the NoSQL side, examples include MongoDB and Cassandra. The term “NoSQL” itself is broad, encompassing databases aimed at diverse use cases.

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    Data Warehouse: Structured Insights

    Data warehouses stand as the bedrock of data management, serving as structured repositories tailored for storing, managing, and analyzing structured data. They excel in providing robust performance for analytical queries. A defining characteristic of data warehouses is their schema-on-write approach, where data undergoes careful structuring and transformation before being loaded into the warehouse.

    Key features of data warehouses include:

    • Structured data. Data warehouses are best suited for structured data, such as sales records, financial data, and customer information.
    • Schema-on-write. Data is carefully structured and transformed before being loaded into the warehouse. This ensures data quality and consistency, but also requires developers to write some code when integrating a new data source, or when an existing one changes its output.
    • Optimized for analytics. Data warehouses are designed for fast query performance, making them ideal for business intelligence and reporting.

    Despite their strengths, data warehouses have limitations in handling unstructured or semi-structured data and real-time data processing.

    Some notable examples include Snowflake, Amazon Redshift, and Apache Hive.

    Warehouse image

    Data Lake: A Flood of Possibilities

    As organizations grapple with larger volumes and diverse types of data from multiple sources, data lakes have emerged as a complementary solution. A data lake is a storage repository capable of holding extensive amounts of raw data in its native format, whether structured, semi-structured, or unstructured.

    Key features of data lakes include:

    • Raw data storage. Data lakes usually store data in its raw form, making it suitable for a wide range of data types. It can be both exported tables from relational databases, plain-text logs collected from multiple systems, and even binary data like images.
    • Schema-on-read. Data is structured and transformed when it’s read, allowing for flexibility in data exploration and analysis.
    • Scalability. Data lakes can very easily scale horizontally to accommodate almost arbitrary data volumes.

    While data lakes excel at storing big data, they can become unwieldy and turn into infamous “data swamps” without proper governance and data cataloging. The typical definition of a data lake doesn’t include utilities for data management, governance, or querying. Some companies have addressed this by introducing the concept of a “data lakehouse” to enhance these functionalities.

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    Data Lakehouse: Best of Both Worlds

    Data lakehouses mark a recent innovation in data management, aiming to bridge the gap between the versatility of data lakes and the structured processing capabilities of data warehouses. They unite both worlds by providing a unified and organized storage infrastructure for structured and semi-structured data while supporting efficient analytical processing. Lakehouses enable traditional “warehouse-style” analytics and querying, built on top of data lakes.

    Key features of data lakehouses include:

    • Still scalable. As lakehouses are built on top of lakes, they still allow for high scalability and storing data in different formats.
    • Schema evolution. They allow for evolving schemas, so data can be ingested in its raw form and structured as needed.
    • Analytics-ready. Data lakehouses provide features for performing queries and data indexing, akin to data warehouses.

    Popular examples of data lakehouse systems include Delta Lake (by Databricks), an open-source storage layer that provides ACID transactions and schema enforcement for data lakes, and Iceberg, an open-source project focusing on an efficient and transactional table format for data lakes, offering the same ease and reliability as data warehouses.

    Data lakehouses are gaining traction as organizations aim to streamline their data architectures, reduce data silos, and enable real-time analytics while maintaining data governance. They represent a promising evolution in the ever-changing landscape of data storage and processing, addressing the challenges posed by the diverse and dynamic nature of modern data.

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    Data Mesh: Data as a Product

    The concept of data mesh proposes a fresh perspective on data, framing it as a product managed by dedicated teams, responsible for its quality, uptime, and more. This product-oriented approach can take various forms, from curated datasets to APIs, and business units within the company can then independently access and utilize these data products.

    Data mesh represents a paradigm shift in data architecture, addressing challenges arising from the growing complexity and scale of data in organizations. It introduces a decentralized approach to data management, departing from the conventional centralized data warehouse model.

    Key principles of data mesh include:

    • Domain-oriented ownership. Data is owned and managed by cross-functional domain teams, which are responsible for data quality, governance, and access.
    • Data as a product. Data is treated as a product, with clear ownership, documentation, and service-level agreements (SLAs) for data consumers.
    • Self-serve data platform. As teams are responsible for providing access to their data, it doesn’t mean that data engineers aren’t necessary. They need to create a platform that would make it easy for teams to share and discover the data they need.
    • Federated compute. Data processing and analytics can now be performed close to where the data resides, reducing data movement and improving performance.

    Though data mesh is gaining attention in the data management community for its ability to tackle decentralization and democratization challenges in large organizations, it may not be suitable for everyone. Smaller companies might find it more practical to opt for a dedicated storage solution that’s easier to set up and manage.

    Combining Approaches

    While I’ve attempted to outline a sort of “timeline” with the emergence of new tools and concepts, it’s crucial to note that older approaches aren’t obsolete or replaced. Organizations are adopting a blend of approaches, leveraging the strengths of various technologies while mitigating potential drawbacks.

    One aspect not addressed here is the growing utilization of machine learning (ML) tools in data management. These tools automate tasks such as data cleansing, quality monitoring, anomaly detection, and predictive analytics. This trend enhances the value and actionability of data by introducing intelligent automation into the data management landscape.