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These settings are available in system.merge_tree_settings and are autogenerated from ClickHouse source.

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min_free_disk_bytes_to_perform_insert

The minimum number of bytes that should be free in disk space in order to insert data. If the number of available free bytes is less than min_free_disk_bytes_to_perform_insert then an exception is thrown and the insert is not executed. Note that this setting:
  • takes into account the keep_free_space_bytes setting.
  • does not take into account the amount of data that will be written by the INSERT operation.
  • is only checked if a positive (non-zero) number of bytes is specified
Possible values:
  • Any positive integer.
If both min_free_disk_bytes_to_perform_insert and min_free_disk_ratio_to_perform_insert are specified, ClickHouse will count on the value that will allow to perform inserts on a bigger amount of free memory.

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min_free_disk_ratio_to_perform_insert

The minimum free to total disk space ratio to perform an INSERT. Must be a floating point value between 0 and 1. Note that this setting:
  • takes into account the keep_free_space_bytes setting.
  • does not take into account the amount of data that will be written by the INSERT operation.
  • is only checked if a positive (non-zero) ratio is specified
Possible values:
  • Float, 0.0 - 1.0
Note that if both min_free_disk_ratio_to_perform_insert and min_free_disk_bytes_to_perform_insert are specified, ClickHouse will count on the value that will allow to perform inserts on a bigger amount of free memory.
Last modified on July 23, 2026