Online Analytical Processing (OLAP)
 What is OLAP?
OLAP (Online Analytical Processing) serves as a computational approach designed to structure data into multi-faceted formats for multifaceted analytical queries. This technology empowers users to efficiently access and query data, execute a range of OLAP operations like slicing, dicing, and drill-down, and explore data to identify underlying trends, relationships, and irregularities. It is extensively employed in areas such as business intelligence, data analytics, and data mining, fulfilling a range of purposes from trend recognition to financial analysis and sales forecasting.
In traditional OLAP systems, a data cube technique is employed to hold information in a multi-dimensional manner, instead of the more common two-dimensional databases. These OLAP cubes can be manipulated—sliced, diced, or pivoted—in various ways to either focus or expand a search query, thereby enabling data visualization from multiple angles. This multi-dimensional feature distinguishes OLAP from OLTP (Online Transaction Processing), which is geared towards capturing and processing real-time transactions in a two-dimensional database.
It's worth noting that contemporary OLAP technologies such as StarRocks have evolved to perform aggregations and joins on-the-fly, allowing for even more dynamic and real-time data analysis. This eliminates the need for pre-built cubes in some scenarios, offering a more streamlined and responsive analytical process.

What Are the Basic OLAP Analytical Operations You Need to Know

Drill-down, roll-up, slice, dice, and pivot are the five fundamental analytical operations performed by OLAP systems to analyze data stored in multidimensional databases. Here is a brief explanation of each:
  • Drill-down: This operation enables users to navigate from a higher level of aggregation to a lower level of detail. For example, drilling down from the year level to the quarter level or from the country level to the city level.
  • Roll-up: Also known as consolidation or drill-up, this operation is the reverse of drill-down. It enables users to move from a lower level of detail to a higher level of aggregation. For instance, rolling up from the month level to the quarter level or from the city level to the country level.
  • Slice: This operation allows users to extract a subset of data from a cube that meets a specific condition. For instance, slicing a cube to view sales data for a particular year or product category.
  • Dice: This operation allows users to extract a subset of data from a cube that meets multiple conditions. For instance, dicing a cube to view sales data for a particular year, product category, and region.
  • Pivot: This operation rotates the axes of a cube, allowing users to view the same data from different perspectives. For example, pivoting a cube to view sales data by product category and month instead of by region and year.

How OLAP works?

Here's how OLAP works with some examples:
  • Data extraction: Gathering data from multiple sources like databases, spreadsheets, and other repositories.
  • Data transformation and cleansing: Ensuring consistency and accuracy by removing errors, duplicates, and discrepancies.
  • Data storage: Storing the cleansed data in a data warehouse, which serves as a central repository.
  • Pre-calculation and aggregation: Summarizing data across dimensions to optimize query performance and reduce response time.
  • Data analysis: Utilizing OLAP clients or business intelligence (BI) tools to perform analytical operations like drill-down, roll-up, slice, dice, and pivot.
  • Visualization and reporting: Presenting the analyzed data in visual formats (charts, graphs, etc.) to support decision-making processes.


OLAP Use Cases

Here are some common use cases for OLAP:
  • Sales forecasting: OLAP can be used to analyze historical sales data, identify trends and patterns, and make predictions about future sales performance.
  • Financial analysis: OLAP can be used to analyze financial data such as revenue, expenses, and profit margins to identify areas of improvement or potential risks.
  • Budgeting and planning: OLAP can be used to analyze data to create budgets and make strategic plans for the future.
  • Customer analysis: OLAP can be used to analyze customer data such as purchase history, demographics, and behavior to identify trends and patterns and improve marketing strategies.
  • Supply chain management: OLAP can be used to analyze data related to inventory, production, and distribution to optimize supply chain operations and reduce costs.
  • Marketing analysis: Marketing teams can use OLAP to analyze customer behavior, purchase patterns, and product preferences. This information can be used to create targeted marketing campaigns that are more likely to be effective.
  • Healthcare analysis: OLAP can be used to analyze patient data, treatment outcomes, and healthcare costs to improve healthcare quality and reduce costs.



OLAP and OLTP are both database management system approaches, but they differ in their purpose, structure, and functionality. Here are the main distinctions between the two:
Primarily designed for data analysis and decision-making support, OLAP allows users to perform complex queries and generate reports on large volumes of data.
Focused on managing day-to-day transactions and operations, OLTP systems ensure data integrity, maintainability, and consistency for real-time business applications.
Data Structure
Organizes data using a multidimensional model, which enables efficient querying and data analysis. Commonly used structures include star schema, snowflake schema, and cube.
Uses a relational model with tables, rows, and columns to store data. It typically employs normalization to minimize data redundancy and improve data integrity.
Query Type and Complexity
Handles complex, ad-hoc queries that usually involve aggregations, calculations, and data exploration across multiple dimensions.
Processes simple, repetitive, and predefined queries that focus on inserting, updating, or deleting data records.
Data Volume and Storage
Manages large volumes of historical and aggregated data, which are often derived from multiple sources and transformed for analysis purposes.
Maintains current, real-time data that is typically more compact and transactional in nature.
Performance Metrics
Prioritizes query response time, as users need quick access to insights and trends for decision-making.
Emphasizes transaction throughput, as a high volume of concurrent transactions must be efficiently processed and maintained.
Data Update Frequency
Usually updated less frequently, as it deals with historical and aggregated data. Updates are performed during ETL (Extract, Transform, Load) processes.
Requires frequent updates to ensure the system stays current with real-time transactions and operations.


Trends in OLAP databases


Cloud-Native Architecture

Modern OLAP databases are cloud-native, featuring key characteristics like:

  • Separation of Compute and Storage: Modern OLAP databases like Snowflake and BigQuery implement a decoupled architecture where compute and storage resources are managed independently. This design allows for dynamic scaling of compute resources (CPU, memory) without impacting data storage, leading to cost-effective scalability and improved performance management.
  • Containerization and Kubernetes Support: New OLAP systems are built to operate within containerized environments, often orchestrated with Kubernetes. This approach offers benefits like easier deployment, better resource utilization, and enhanced scalability. It also facilitates running OLAP databases in a microservices architecture.

Performance: Sub-Second vs. Seconds/Minutes Response Time

The substantial improvement in query response times within the OLAP domain, shifting from minutes or seconds to sub-second responses, is primarily attributed to two key technological advancements: query optimization and vectorized query execution. These enhancements are exemplified in modern systems like StarRocks, known for efficiently handling extensive datasets (ranging from terabytes to petabytes) with rapid response times.

  • Query Optimization: Advanced query execution engines and optimization techniques are employed to reduce response times. Techniques like columnar storage, in-memory processing, and advanced indexing significantly enhance query performance, particularly for large-scale data analysis.
  • Vectorized Query Execution: Some OLAP systems use vectorized processing, where operations are performed on multiple data points simultaneously, rather than one at a time. This approach leverages CPU vector instructions for faster computation.

Data Handling: Streaming vs. Batch Data

  • Streaming Data Integration: Modern OLAP databases incorporate streaming data capabilities, allowing for real-time data analysis. This is achieved through integrations with streaming platforms like Apache Kafka, facilitating continuous data ingestion and immediate analytical processing.
  • Data Sharding and Partitioning: Efficient data distribution techniques, like sharding and partitioning, are crucial for managing large datasets. They help in distributing the data across multiple nodes to balance the load and improve query performance.

Storage: Remote (Object) Storage vs. Local (SSD) Storage

In modern OLAP solutions, there's a growing trend towards using remote object storage instead of local SSD storage. This shift is primarily driven by two key factors:

  • Cost Efficiency of Remote Object Storage: Object storage, such as Amazon S3, Google Cloud Storage, or Azure Blob Storage, is significantly cheaper than traditional storage methods like Elastic Block Store (EBS) or local SSDs. This cost advantage is particularly compelling for large-scale data warehousing where storing petabytes of data economically is crucial.

  • Performance Considerations: Despite the cost benefits, there are performance considerations. Local SSDs offer high I/O throughput and lower latency, ideal for rapid data access and processing. However, modern OLAP systems have made significant strides in optimizing remote object storage to achieve near-SSD performance levels. They utilize techniques like data compression and efficient retrieval algorithms to enhance access speeds and reduce latency.

The move to remote object storage in OLAP systems represents a balancing act between achieving cost efficiency and maintaining high performance, a critical consideration in handling the large and growing volumes of data in today's analytical environments.

Open Table Format vs. Product Native Storage Format


Open Table Format vs. Product Native Storage Format.001

Modern OLAP databases support open table formats, allowing integration with various open-source standards like Apache Iceberg, Apache Hudi, Hive, and Paimon. This approach contrasts with proprietary, product-native formats, promoting greater flexibility and interoperability in data management.

In summary, the technical advancements in the OLAP landscape reflect a shift towards more flexible, efficient, and powerful systems capable of handling the growing complexity and volume of data in the modern analytical environment. These improvements span across architecture, performance optimization, data handling, storage management, and advanced analytical capabilities, ensuring that OLAP databases remain a critical component in the data management and analytics infrastructure.