Cache Types

When performing queries, ClickHouse uses different caches.

Main cache types:

• mark_cache — Cache of marks used by table engines of the MergeTree family.
• uncompressed_cache — Cache of uncompressed data used by table engines of the MergeTree family.
• Operating system page cache (used indirectly, for files with actual data).

Additional cache types:

• DNS cache.
• Regexp cache.
• Compiled expressions cache.
• Avro format schemas cache.
• Dictionaries data cache.
• Schema inference cache.
• Filesystem cache over S3, Azure, Local and other disks.
• Query cache.

To drop one of the caches, use SYSTEM DROP ... CACHE statements.