Set up docs MCPThese settings are available in system.merge_tree_settings and are autogenerated from ClickHouse source.
text_index_dictionary_block_frontcoding_compression
Version history
| Version | Default value | Comment |
|---|---|---|
| 26.6 | 1 | New setting |
Default front-coding compression for text index dictionary blocks.
Can be overridden by explicit dictionary_block_frontcoding_compression index argument.
text_index_dictionary_block_size
Version history
| Version | Default value | Comment |
|---|---|---|
| 26.6 | 512 | New setting |
Default dictionary block size for text indexes.
Can be overridden by explicit dictionary_block_size index argument.
text_index_max_memory_usage_before_flush
Version history
| Version | Default value | Comment |
|---|---|---|
| 26.8 | 1073741824 | New setting. The previous value disables memory-based flushing to preserve pre-26.8 behavior |
Maximum estimated memory retained by a text index builder before flushing a temporary segment.
text_index_max_processed_tokens_before_flush
Version history
| Version | Default value | Comment |
|---|---|---|
| 26.8 | 100000000 | New setting |
Maximum number of processed tokens accumulated by a text index builder before flushing a temporary segment.
text_index_posting_list_block_size
Version history
| Version | Default value | Comment |
|---|---|---|
| 26.6 | 1048576 | New setting |
Default posting list block size for text indexes (rows).
Can be overridden by explicit posting_list_block_size index argument.
text_index_posting_list_codec
Version history
| Version | Default value | Comment |
|---|---|---|
| 26.6 | none | New setting |
Default posting list codec for text indexes.
Can be overridden by explicit posting_list_codec index argument.
text_index_serialization_version
Version history
| Version | Default value | Comment |
|---|---|---|
| 26.8 | v2_with_positions | Allow the 'v2_with_positions' text index format that persists token positions for phrase search. Reverts to 'v1_with_codec' under older compatibility so that newer servers keep writing the format that older servers can read during a rolling upgrade. |
| 26.6 | v1_with_codec | New setting. Controls the on-disk format version of text indexes. Reverts to 'v0_initial' under older compatibility so that newer servers keep writing the previous format that older servers can read during a rolling upgrade. |
The preferred on-disk serialization format version for writing text indexes.
The setting is a preference rather than a hard constraint: if the configured version cannot represent an index, a newer version that can represent it is chosen automatically, and writing a text index never fails because of this setting.
During a rolling upgrade, pin the format with the profile-level compatibility setting on
the already upgraded servers, so that they keep writing the format that older servers can still read.
Possible values:
v0_initial— The original format. Does not persist the posting list codec type.v1_with_codec— Persists the posting list codec type in the text index header.v2_with_positions— Persists token positions for indexes withsupport_phrase_search.