Shiv Iyer, Author at ChistaDATA Inc.

ClickHouse EXPLAIN: Display & Analyze Execution Plans

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. […]

ClickHouse Permutation by Recursion and Cross Join

Shiv Iyer

Permutation is the process of arranging a set of elements in all possible orders. ClickHouse supports two methods for computing permutations: recursion and cross join. Here’s how each method works, along with real-life data examples […]

Deep Dive into ClickHouse SORT Operation and Index Scan

Shiv Iyer

Introduction In ClickHouse, a SORT operation is used to sort data in a specified order, either ascending or descending. Sorting data can improve query performance when the data is accessed in a sorted order, such […]

ClickHouse JOIN Optimizations for Query Performance

How to optimize JOIN operations in ClickHouse?

Shiv Iyer

Introduction Join operations in ClickHouse can be optimized in several ways to improve query performance. Here are some best practices to optimize join operations in ClickHouse, along with real-life data examples: Example: Suppose we have […]

Anti Money Laundering Systems with ChistaDATA's ClickHouse

Customer Stories: Real-time Anti Money Laundering Systems in Modern Banking with ChistaDATA’s ClickHouse

Shiv Iyer

Introduction ChistaDATA is a data science and engineering company based in San Francisco Bay Area, that specializes in building data-driven solutions for Financial Services on ClickHouse. One of their recent projects involved building a real-time […]

How Data Skipping Indexes are implemented in ClickHouse?

Shiv Iyer

Introduction Data skipping indexes in ClickHouse help improve query performance by allowing the system to skip over irrelevant data parts while reading from disk. They are a type of secondary index that store summary information […]

Why don’t we recommend INDEX RANGE SCAN on large Data Sets in ClickHouse

Shiv Iyer

INDEX RANGE SCAN is a type of index access method used in ClickHouse to retrieve data from an index based on a range of values. While INDEX RANGE SCAN can be very efficient for small […]

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Articles by Shiv Iyer

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

ClickHouse Permutation by Recursion and Cross Join

Deep Dive into ClickHouse SORT Operation and Index Scan

How to optimize JOIN operations in ClickHouse?

Customer Stories: Real-time Anti Money Laundering Systems in Modern Banking with ChistaDATA’s ClickHouse

How Data Skipping Indexes are implemented in ClickHouse?

Why don’t we recommend INDEX RANGE SCAN on large Data Sets in ClickHouse