low_cardinality_allow_in_native_format
Allows or restricts using the LowCardinality data type with the Native format. If usage ofLowCardinality is restricted, ClickHouse server converts LowCardinality-columns to ordinary ones for SELECT queries, and convert ordinary columns to LowCardinality-columns for INSERT queries.
This setting is required mainly for third-party clients which do not support LowCardinality data type.
Possible values:
- 1 — Usage of
LowCardinalityis not restricted. - 0 — Usage of
LowCardinalityis restricted.
low_cardinality_max_dictionary_size
Sets a maximum size in rows of a shared global dictionary for the LowCardinality data type that can be written to a storage file system. This setting prevents issues with RAM in case of unlimited dictionary growth. All the data that can’t be encoded due to maximum dictionary size limitation ClickHouse writes in an ordinary method. Possible values:- Any positive integer.
low_cardinality_use_single_dictionary_for_part
Turns on or turns off using of single dictionary for the data part. By default, the ClickHouse server monitors the size of dictionaries and if a dictionary overflows then the server starts to write the next one. To prohibit creating several dictionaries setlow_cardinality_use_single_dictionary_for_part = 1.
Possible values:
- 1 — Creating several dictionaries for the data part is prohibited.
- 0 — Creating several dictionaries for the data part is not prohibited.