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query_cache

Querying in ClickHouse Cloud

The data in this system table is held locally on each node in ClickHouse Cloud. Obtaining a complete view of all data, therefore, requires the clusterAllReplicas function. See here for further details.

Shows the content of the query cache.

Columns:

  • query (String) — Query string.
  • query_id (String) — ID of the query.
  • result_size (UInt64) — Size of the query cache entry.
  • tag (LowCardinality(String)) — Tag of the query cache entry.
  • stale (UInt8) — If the query cache entry is stale.
  • shared (UInt8) — If the query cache entry is shared between multiple users.
  • compressed (UInt8) — If the query cache entry is compressed.
  • expires_at (DateTime) — When the query cache entry becomes stale.
  • key_hash (UInt64) — A hash of the query string, used as a key to find query cache entries.

Example

SELECT * FROM system.query_cache FORMAT Vertical;
Row 1:
──────
query:       SELECT 1 SETTINGS use_query_cache = 1
query_id:    7c28bbbb-753b-4eba-98b1-efcbe2b9bdf6
result_size: 128
tag:
stale:       0
shared:      0
compressed:  1
expires_at:  2023-10-13 13:35:45
key_hash:    12188185624808016954

1 row in set. Elapsed: 0.004 sec.