About Can Sayn
Can Sayın is experienced Database Administrator in open source relational and NoSql databases, working in complicated infrastructures. Over 5 years industry experience, he gain managing database systems. He is working at ChistaDATA Inc. His areas of interest are generally on open source systems.
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Check ClickHouse Disks

Following query will show you ClickHouse Disks via reading system.disks table. SELECT name, path, formatReadableSize(sum(free_space)) as free_space, formatReadableSize(sum(total_space)) as total_space, formatReadableSize(sum(keep_free_space)) as keep_free_space, type FROM system.disks GROUP BY name, path, type FORMAT PrettyCompact Example Output: […]

Check Queries That Being Processed In ClickHouse

Following sql query will show you queries that being processed. SELECT user, address as client, elapsed as time_seconds, formatReadableSize(memory_usage) as memory, formatReadableSize(read_bytes) as read, read_rows, total_rows_approx as total_rows, query_id, substring(query,1,40) as query FROM system.processes ORDER […]

Maximizing Performance With ClickHouse Index Granularity

In the world of data analytics and storage, databases are the backbone that supports businesses’ decision-making processes. ClickHouse, an open-source columnar database management system, has gained popularity for its exceptional speed and efficiency in handling […]

Removing Empty Parts In ClickHouse

The new feature of empty part removal was introduced in version 20.12. If TTL removes all rows from a part, older versions leave empty parts (with 0 rows) (see https://github.com/ClickHouse/ClickHouse/issues/5491). If you establish a TTL […]

Check Current TTL Settings in ClickHouse

Run a query on system.parts to see the absolute TTL values for a particular piece of data. For each section, columns indicate any TTL restrictions that are currently in effect. SELECT * FROM system.parts WHERE […]

Time Zones In ClickHouse

DateTime in ClickHouse refers to the number of seconds since 1970-01-01 00:00:00 GMT or UNIX timestamp. Both on the server (for HTTP clients and certain types of queries, such toString(ts)) and on the client (for […]

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