ClickHouse DBA Script Archives | Page 6 of 10

ClickHouse Replication: Understanding High Watermark Mechanism for Horizontal Scaling

Introduction In ClickHouse, the term “high watermark” refers to a mechanism used to track the progress of data replication in a distributed environment. It helps ensure data consistency and integrity across multiple replicas of a ClickHouse […]

From Snowflake to ClickHouse: How ChistaDATA Enabled the World’s Largest Ad Tech Platform’s Migration and Built an Optimal Real-Time Analytics Infrastructure

Shiv Iyer

Introduction The world of advertising technology is fast-paced, data-intensive, and requires real-time insights for efficient decision-making. In this case study, we explore how ChistaDATA, a leading provider of advanced analytics solutions, helped the world’s largest […]

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 […]

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. […]

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 […]

* Everything changes over time – Our blogs/posts and comments changes over time, That’s how it should be! Whatever we comment from ChistaDATA Inc. Teams (including Shiv Iyer) and other stakeholders or guest bloggers posted here are never permanent, These things worked for us. But, there is no guarantee they will work for you too, When using the recommendations from ChistaDATA or MinervaDB or MinervaSQL or any other online resources / Google, You must test the advice before applying them to your production systems, and always invest for a robust Database DR solution, Thank you for understanding.

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