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filimonov
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Mar 4, 2026
| WHERE active | ||
| ) b | ||
| ON a.database = b.database AND a.table = b.table AND a.partition_id = b.partition_id | ||
| WHERE a.min_block_number IS NOT NULL |
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Do we really want to suggest removing all?
| Here is a quick way to find out if you have detached parts along with the reason why. | ||
| ### Monitoring of detached parts | ||
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| You can find information in `clickhouse-server.log`, for what happened when the parts were detached during startup. If `clickhouse-server.log` is lost it might be impossible to figure out what happened and why the parts were detached. |
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part_log fragment disappeared.
filimonov
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Mar 4, 2026
| Here is a query that can help with investigations. It looks for active parts containing the same data blocks as the detached parts and generates commands to drop the detached parts. | ||
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| ```sql | ||
| SELECT a.*, |
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since we generating set of ALTER statements there, i would put all missing details to the comment of ALTER, to simplify copy and paste.
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Updated detached-parts KB with safer cleanup guidance and query fixes: added warnings before destructive actions, added asynchronous detached-part monitoring queries, fixed the bulk DROP DETACHED helper to use system.detached_parts block columns (validated locally), and shortened appendix/reference links for readability.
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