Transfer the data from MySQL into ClickHouse Recommended solution – MinervaDB ClickHouse MySQL Data Reader (forked from Alitinity/clickhouse-mysql-data-reader ) GitHub – https://github.com/MinervaDB/MinervaDB-ClickHouse-MySQL-Data-Reader Installation and configuration ** Prerequisites – we have to install pip3 […]
Attaches a table or a dictionary, for example, when moving a database to another server. The query does not create data on the disk, but assumes that data is already in the appropriate places, and […]
Log of query execution Controlled by session level setting send_logs_level Possible values: ‘trace’, ‘debug’, ‘information’, ‘warning’, ‘error’, ‘fatal’, ‘none’ Can be used with clickhouse-client in both interactive and non-interactive mode. clickhouse-client -mn –send_logs_level=’trace’ –query “SELECT sum(number) FROM numbers(1000)” Result; […]
In this article, you will learn how to read your data from ClickHouse which is stored in MongoDB. MongoDB engine is read-only table engine which allows to read data (SELECT queries) from remote MongoDB collection. Engine […]
In ClickHouse, there is a table called query_log which is located in system database. query_log table gives you information about all the queries running on the database. This is an useful option for troubleshooting […]
What is Materialized View | What should it mean to us? While normal views only store the queries and fetch the data from the related tables according to the specified criteria when requested, materialized views […]
There are two kinds of kill statements: to kill a query and to kill a mutation. KILL QUERY Attempts to forcibly terminate the currently running queries. The queries to terminate are selected from the system.processes […]
Alert Name Shell or SQL command Severity ClickHouse status $ curl ‘http://localhost:8123/’ Ok. Critical Too many simultaneous queries. Maximum: 100 (by default) select value from system.metrics where metric=’Query’ Critical Replication status $ curl ‘http://localhost:8123/replicas_status’ Ok. […]
With system tables, you can learn the details of the tables and columns on ClickHouse with the following queries. In this article, we will explain two system tables and give examples. First, system.parts table. […]
Introduction to Skipping Indexes When working on ClickHouse, many different factors can affect its performance of Clickhouse. One of the most critical elements is that ClickHouse determines whether it will use a primary key when […]
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