How to Monitor PageIOLatch Waits in ClickHouse
Introduction PageIOLatch waits are a type of wait event that occurs when a thread is waiting for a page to be read from disk into memory. In ClickHouse, these waits are implemented as part of […]
ClickHouse DBA Script
Leveraging ClickHouse for Real-Time Predictive Analytics
Introduction Predictive analytics solutions require fast and scalable storage solutions that can handle large amounts of data and support real-time analysis. ClickHouse is a columnar database management system optimized for OLAP (Online Analytical Processing) workloads […]
Monitoring ClickHouse Query Parser Performance
Introduction To monitor the Parser performance in ClickHouse, you can use the system.query_log system table, which contains information about all queries executed in the cluster. Here’s an example SQL code that you can use to […]
How does ClickHouse Resource Governor work?
Introduction ClickHouse Resource Governor is a feature that allows DBAs to allocate system resources, such as CPU, memory, and I/O operations, to specific users or groups of users. The Resource Governor provides a way to […]
ClickHouse Troubleshooting: Avoiding Excessive Disk Swaps
Introduction Disk swapping is a technique used by operating systems to manage memory usage when the amount of available physical memory is limited. When the operating system runs out of available physical memory, it uses […]
Using TOP Command to Measure ClickHouse Server Load & Queue Length
Introduction Measuring load and queue length of ClickHouse Server is important for troubleshooting performance bottleneck. The load is a measure of the amount of work that ClickHouse is currently doing or is capable of doing. […]
How to Monitor & Troubleshoot Log Contention in ClickHouse
Introduction Log contention in ClickHouse occurs when multiple write operations compete for the same log file, causing performance issues and potentially leading to data corruption. Here are some steps you can take to troubleshoot and […]
Monitoring Query Latency due to Wait and Latch Events in ClickHouse
Introduction In ClickHouse, you can monitor query latency and waits/latches using the system.query_log and system.metrics tables. Here is an example query that can be used to monitor query latency and wait/latch events: This query selects […]
ClickHouse Troubleshooting: How NULL Values affect Query Performance
Introduction NULL values in ClickHouse can affect performance in several ways. One way is that they can increase the size of data, which can lead to slower query execution times as more data needs to […]
ClickHouse Troubleshooting: How to Identify Blocks Causing Latch Contention
Introduction Latch contention in ClickHouse can have a significant impact on performance. A latch is a synchronization mechanism that allows multiple threads to access a shared resource, such as a data block, in a controlled […]