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Querying in ClickHouse CloudThe 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.

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Description

Contains logging entries with information about various blob storage operations such as uploads and deletes. It is safe to truncate or drop this table at any time.

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Columns

  • hostname (LowCardinality(String)) — Hostname of the server executing the query.
  • clickhouse_version (LowCardinality(String)) — Version of the ClickHouse server that produced the row.
  • system_processor (LowCardinality(String)) — CPU architecture of the ClickHouse server that produced the row.
  • event_date (Date) — Date of the event.
  • event_time (DateTime) — Time of the event.
  • event_time_microseconds (DateTime64(6)) — Time of the event with microseconds precision.
  • event_type (Enum8(‘Upload’ = 1, ‘Delete’ = 2, ‘MultiPartUploadCreate’ = 3, ‘MultiPartUploadWrite’ = 4, ‘MultiPartUploadComplete’ = 5, ‘MultiPartUploadAbort’ = 6, ‘Read’ = 7, ‘Copy’ = 8)) — Type of the event. Possible values: ‘Upload’, ‘Delete’, ‘MultiPartUploadCreate’, ‘MultiPartUploadWrite’, ‘MultiPartUploadComplete’, ‘MultiPartUploadAbort’, ‘Read’, ‘Copy’
  • query_id (String) — Identifier of the query associated with the event, if any.
  • thread_id (UInt64) — Identifier of the thread performing the operation.
  • thread_name (String) — Name of the thread performing the operation.
  • disk_name (LowCardinality(String)) — Name of the associated disk.
  • bucket (String) — Name of the bucket.
  • remote_path (String) — Path to the remote resource.
  • local_path (String) — Path to the metadata file on the local system, which references the remote resource.
  • source_bucket (String) — Name of the bucket the object was copied from, for the ‘Copy’ event. Empty for other events.
  • source_remote_path (String) — Path to the object the data was copied from, for the ‘Copy’ event. Empty for other events.
  • data_size (UInt64) — Size of the data involved in the operation.
  • elapsed_microseconds (UInt64) — Elapsed time for the operation, in microseconds.
  • connection_id (UInt64) — Identifier of the HTTP connection that carried the operation, unique within the server process. Group by this to follow one connection: the OS recycles ports and socket inodes as soon as a socket closes, so those cannot tell consecutive connections apart. 0 if no single HTTP request can be attributed to this row: the operation used no HTTP connection; it used more than one - a retried write is logged as a single row whose elapsed time covers all of its attempts, and no single connection describes it; or it shared one request with other rows - a batched delete writes one Delete row per object and attributes the connection to the first of them only. All connection_* columns are meaningful only when connection_id is not 0; otherwise they are all 0.
  • connection_local_port (UInt16) — Local TCP port of that connection. Unique only among sockets open at the same moment; use it to join against a packet capture or a /proc/net/tcp row taken at the time.
  • connection_socket_inode (UInt64) — Socket inode of that connection, as reported by fstat. Same caveat as the port: unique only while the socket is open. 0 if the OS exposes no inode for sockets, as on macOS.
  • connection_requests (UInt32) — Number of requests the connection had already sent before this one. 0 means this was its first request, provided connection_id is not 0.
  • connection_age_microseconds (UInt64) — Time since the connection’s TCP socket was established. Reset by every reconnect, so it measures the life of the socket rather than of the session object.
  • connection_idle_microseconds (UInt64) — Time the connection sat idle in the pool before being handed out for this operation. 0 on a connection’s first request, and also when connection_id is 0.
  • error_code (Int32) — Error code of the operation. 0 if there was no error.
  • error (String) — Error message associated with the event, if any.

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Example

Suppose a blob storage operation uploads a file, and an event is logged:
In this example, upload operation was associated with the INSERT query with ID 7afe0450-504d-4e4b-9a80-cd9826047972. The local metadata file store/654/6549e8b3-d753-4447-8047-d462df6e6dbe/tmp_insert_all_1_1_0/checksums.txt refers to remote path rrr/kxo/tbnqtrghgtnxkzgtcrlutwuslgawe in bucket bucket1 on disk disk_s3, with a size of 259 bytes.

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See also