clickhouse troubleshooting Archives

ClickHouse Troubleshooting Techniques: 8 Proven Drills We Teach

The ClickHouse troubleshooting techniques taught in CHT-400 at ChistaDATA University: a scope, prove, fix method and the diagnostic queries for eight production incidents, from too many parts to distributed timeouts.

[…]

ClickHouse TTL: How Deletes Are Scheduled and 6 Reasons They Fail

ChistaDATA Inc.

A ClickHouse TTL clause is not a delete queue. There is no background reaper walking rows and checking expiry timestamps. A TTL expression on a MergeTree table is a promise that expired rows will be […]

ClickHouse Sharding Troubleshooting and Performance Optimization

ChistaDATA Inc.

A field guide to ClickHouse sharding troubleshooting: Distributed send-queue backlogs, duplicate rows from internal_replication, shard skew, initiator merge bottlenecks, distributed JOIN failures and unavailable shards, each with the system.* evidence, the mechanism, the staged fix, and the alert that catches it early.

[…]

ClickHouse Explain

ClickHouse EXPLAIN PIPELINE: A Proven 7-Step Guide to Decoding Query Execution Bottlenecks

ChistaDATA Inc.

Read ClickHouse EXPLAIN PIPELINE like a principal engineer: processor names, x1 choke points, and measured confirmation via system.processors_profile_log.

[…]

ClickHouse Shard Contention Troubleshooting: A Complete Guide

ChistaDATA Inc.

ClickHouse shard contention is one of the most frustrating performance problems a distributed database team can face. When a cluster scales out to dozens or hundreds of nodes, the promise of linear scalability quietly breaks […]

ClickHouse Telemetry Retention: TTL Policies That Control Cost

ChistaDATA Inc.

ClickHouse telemetry retention: a practical look at how it works, what to tune, and the pitfalls that trip up production ClickHouse.

[…]

ClickHouse Projections: A Complete Guide to Query Optimization

Shiv Iyer

ClickHouse Projections: A Complete Guide to Query Optimization What Are ClickHouse Projections? ClickHouse projections are specialized inner tables that exist within a main table, designed to dramatically improve query performance by pre-computing and storing data […]

ClickHouse Storage Engines

ChistaDATA Inc.

ClickHouse Storage Engines: The Complete Guide to Optimal Performance ClickHouse has revolutionized the analytics database landscape with its lightning-fast query performance and innovative storage architecture. At the heart of this performance lies a sophisticated system […]

ClickHouse Query Optimizer

Shiv Iyer

ClickHouse Query Optimizer: How It Transforms Your SQL Into Lightning-Fast Execution ClickHouse’s reputation for blazing-fast analytics isn’t accidental – it’s the result of a sophisticated query optimization pipeline that transforms your SQL into highly efficient […]

Data Security and Data Masking in ClickHouse

Shiv Iyer

Comprehensive Guide to Data Security and Data Masking in ClickHouse: Protecting Your Data While Maintaining Performance In today’s data-driven landscape, organizations face the dual challenge of leveraging their data for insights while ensuring robust protection […]

* 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.

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

PostgreSQL is a registered trademark of the PostgreSQL Community Association. ClickHouse is a registered trademark of ClickHouse, Inc. MongoDB is a registered trademark of MongoDB, Inc. Couchbase is a registered trademark of Couchbase, Inc. Redis is a registered trademark of Redis Ltd. Apache Cassandra is a registered trademark of the Apache Software Foundation. Milvus is a registered trademark of Zilliz. MinIO is a registered trademark of MinIO, Inc. Amazon Redshift and Amazon Aurora are registered trademarks of [Amazon.com](http://amazon.com/), Inc. Google Cloud is a registered trademark of Google LLC. Snowflake is a registered trademark of Snowflake Inc. Databricks is a registered trademark of Databricks, Inc. MySQL and InnoDB are registered trademarks of Oracle Corporation. MariaDB is a trademark of MariaDB Corporation Ab. All other trademarks are the property of their respective owners. Any other product or company names mentioned may be trademarks or trade names of their respective owners. Copyright © 2010–2026. All Rights Reserved by ChistaDATA®.