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system.filesystem_cache_settings

Description​

Contains information about all filesystem cache settings

Columns​

  • cache_name (String) — Cache name
  • path (String) — Cache directory path
  • max_size (UInt64) — Maximum cache size
  • max_elements (UInt64) — Maximum number of cache elements, e.g. file segments (limits number of files on filesystem)
  • max_file_segment_size (UInt64) — Maximum size of a single file segment
  • boundary_alignment (UInt64) — File segment alignment
  • cache_on_write_operations (UInt8) — Enables write-through cache (cache on INSERT and MERGE)
  • cache_policy (String) — Cache eviction policy
  • slru_size_ratio (Float64) — SLRU cache policy size ratio of protected to probationary elements
  • background_download_threads (UInt64) — Number of background download threads. Value 0 disables background download
  • background_download_queue_size_limit (UInt64) — Size of background download queue. Value 0 disables background download
  • background_download_max_file_segment_size (UInt64) — Maximum size which can be downloaded in background download
  • load_metadata_threads (UInt64) — Number of threads to load cache metadata at server startup. Value 0 disables asynchronous loading of metadata
  • load_metadata_asynchronously (UInt8) — Enables asynchronous loading of metadata on server startup
  • keep_free_space_size_ratio (Float64) — A ratio of free space which cache would try to uphold in the background
  • keep_free_space_elements_ratio (Float64) — A ratio of free elements which cache would try to uphold in the background
  • keep_free_space_remove_batch (UInt64) — A remove batch size of cache elements made by background thread which upholds free space/elements ratio
  • enable_filesystem_query_cache_limit (UInt8) — Enable limiting maximum size of cache which can be written within a query
  • cache_hits_threshold (UInt64) — Deprecated setting
  • enable_bypass_cache_with_threshold (UInt8) — Undocumented. Not recommended for use
  • bypass_cache_threshold (UInt64) — Undocumented. Not recommended for use
  • write_cache_per_user_id_directory (UInt8) — Internal ClickHouse Cloud setting
  • allow_dynamic_cache_resize (UInt8) — Allow dynamic resize of filesystem cache
  • max_size_ratio_to_total_space (Float64) — Ratio of max_size to total disk space
  • skip_cache_on_disk_failure (UInt8) — If true, bypass filesystem cache operations silently on disk IO errors. If false (default), disk IO errors are propagated as startup failures.
  • use_split_cache (UInt8) — Use separation of files to system/data.
  • split_cache_ratio (Float64) — Ratio of system segment to total size of cache for split_cache.
  • overcommit_eviction_evict_step (UInt64) — Eviction step in bytes for overcommit eviction policy. Used for keep_free_space_*_ratio settings
  • check_cache_probability (Float64) — Works only for debug or sanitizer build. Checks cache correctness by going through all cache and checking state of each cache element
  • is_initialized (UInt8) — Indicates whether cache was successfully initialized
  • current_size (UInt64) — Current cache size
  • current_elements_num (UInt64) — Current cache elements (file segments) number