enable_adaptive_codec_selection
When enabled, merges and mutations choose a codec per block for columns that use the default codec (noCODEC clause, or CODEC(Default)).
The candidates are the table’s default codec (see the default_compression_codec setting), NONE, and specialized codecs suited to the column type, each on its own and, when the default codec is a general-purpose compression such as LZ4 or ZSTD, followed by it.
The smallest output wins. Compression is therefore never worse than the default, and incompressible blocks are stored raw.
A column whose default codec includes encryption (e.g. AES_128_GCM_SIV) is never selected adaptively, so encryption is always applied.
Per-block codecs are reported by the mergeTreeCodecBlockCounts table function.
enable_index_granularity_compression
Compress in memory values of index granularity if it is possibleenable_max_bytes_limit_for_min_age_to_force_merge
If settingsmin_age_to_force_merge_seconds and
min_age_to_force_merge_on_partition_only should respect setting
max_bytes_to_merge_at_max_space_in_pool.
Possible values:
truefalse
enable_mixed_granularity_parts
Enables or disables transitioning to control the granule size with theindex_granularity_bytes setting. Before version 19.11, there was only the
index_granularity setting for restricting granule size. The
index_granularity_bytes setting improves ClickHouse performance when
selecting data from tables with big rows (tens and hundreds of megabytes).
If you have tables with big rows, you can enable this setting for the tables
to improve the efficiency of SELECT queries.
enable_replacing_merge_with_cleanup_for_min_age_to_force_merge
Whether to use CLEANUP merges for ReplacingMergeTree when merging partitions down to a single part. Requiresallow_experimental_replacing_merge_with_cleanup,
min_age_to_force_merge_seconds and min_age_to_force_merge_on_partition_only
to be enabled.
Possible values:
truefalse
enable_row_mask_update_coalescing
Coalesce adjacent singletonUPDATE _row_exists = 0 commands while mutating a
Wide part with Full storage. The persisted mutation commands and their
versions are unchanged.
Set to false to execute each command separately.
enable_the_endpoint_id_with_zookeeper_name_prefix
Enable the endpoint id with zookeeper name prefix for the replicated merge tree table.enable_vertical_merge_algorithm
Allows eligible background merges to use the vertical merge algorithm. Vertical merges process columns separately to reduce peak memory usage for wide tables, potentially at the cost of merge speed. Setting this to0 forces horizontal merges; a non-zero value only permits vertical merges—the part format, table engine, TTL operation, and vertical_merge_algorithm_min_* thresholds still determine whether it is selected.