Articles by Shiv Iyer

About Shiv Iyer

Open Source Database Systems Engineer with a deep understanding of Optimizer Internals, Performance Engineering, Scalability and Data SRE. Shiv currently is the Founder, Investor, Board Member and CEO of multiple Database Systems Infrastructure Operations companies in the Transaction Processing Computing and ColumnStores ecosystem. He is also a frequent speaker in open source software conferences globally.

Real-Time Analytics Strategy for Telcos

Shiv Iyer

The telecommunications industry is experiencing unprecedented growth and transformation, driven by technological advancements, increasing customer demands, and evolving market dynamics. To stay relevant and competitive in this rapidly changing landscape, Telcos need to harness the […]

Achieving Real-time Analytics with ChistaDATA’s ClickHouse

Shiv Iyer

Introduction Once upon a time, in a rapidly evolving digital landscape, businesses faced the challenge of delivering real-time analytics to gain valuable insights and stay ahead of the competition. One company, ChistaDATA, emerged as a […]

Do Parallel Query Execution Plans improve ClickHouse Performance?

Shiv Iyer

Introduction Parallel query execution in ClickHouse can have both positive and negative effects on performance, depending on the specific use case and the characteristics of the data set. Potential Impact on ClickHouse performance Here’s an […]

Direct Path Load and Space Management in ClickHouse

Direct Path Load and Space Management for Optimal ClickHouse Storage & Ingestion

Shiv Iyer

Introduction Space management and direct path load are important considerations in ClickHouse for optimizing storage efficiency and data loading performance. Here are some tips and tricks for space management and direct path load in ClickHouse: […]

Accuracy of Cardinality Estimates in ClickHouse Execution Plans

ClickHouse Performance: How to assess Accuracy of Cardinality Estimates in Execution Plans

Shiv Iyer

Introduction In ClickHouse, evaluating the accuracy of cardinality estimates in a query plan can be challenging since ClickHouse relies on different heuristics and sampling techniques to estimate cardinalities. Accuracy of Cardinality Estimates However, you can […]

How to drop an Existing Histogram from a ClickHouse Column?

Shiv Iyer

Introduction To drop an existing histogram on a ClickHouse column and prevent the Auto Stats gathering job from creating it in the future, you can follow these steps: For example: Identify the column name that […]

ClickHouse EXPLAIN: Display & Analyze Execution Plans

Shiv Iyer

Introduction To display and read the execution plans for a SQL statement in ClickHouse, you can follow these steps using real-life data sets: For this example, we’ll use a simple SELECT statement to retrieve data […]

How to Identify Overlapping Date Ranges in ClickHouse

ClickHouse SQL Engineering: How to Identify Overlapping Date Ranges

Shiv Iyer

To identify overlapping date ranges in ClickHouse, you can use SQL queries that compare the start and end dates of each range to determine if there are any overlaps. Example to identify Overlapping Date Ranges […]

Using GROUPBY for Groupings, Rolllups and Cubes in ClickHouse

Using GROUPBY for Groupings, Rollups and Cubes in ClickHouse

Shiv Iyer

Introduction Grouping, rollup, and cube are SQL query operations that allow for grouping and aggregation of data based on multiple dimensions or attributes. In ClickHouse, these operations are implemented using the GROUP BY clause, which […]

Derived Tables for Query Performance in ClickHouse

Shiv Iyer

Introduction Derived tables are tables that are created on-the-fly as a result of a query. They are temporary tables that exist only for the duration of the query, and are not stored in the database. […]

ChistaDATA Inc.

Enterprise-class 24*7 ClickHouse Consultative Support and Managed Services

Articles by Shiv Iyer

Real-Time Analytics Strategy for Telcos

Achieving Real-time Analytics with ChistaDATA’s ClickHouse

Do Parallel Query Execution Plans improve ClickHouse Performance?

Direct Path Load and Space Management for Optimal ClickHouse Storage & Ingestion

ClickHouse Performance: How to assess Accuracy of Cardinality Estimates in Execution Plans

How to drop an Existing Histogram from a ClickHouse Column?

ClickHouse EXPLAIN: Display & Analyze Execution Plans

ClickHouse SQL Engineering: How to Identify Overlapping Date Ranges

Using GROUPBY for Groupings, Rollups and Cubes in ClickHouse

Derived Tables for Query Performance in ClickHouse