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system.delta_lake_metadata_log

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.

Description​

The system.delta_lake_metadata_log table records metadata access and parsing events for Delta Lake tables read by ClickHouse. It provides detailed information about each metadata file, which is useful for debugging, auditing, and understanding Delta table structure evolution.

This table logs every metadata file read from Delta Lake tables. It helps users trace how ClickHouse interprets Delta table metadata and diagnose issues related to schema evolution, snapshot resolution, or query planning.

Note

This table is primarily intended for debugging purposes.

Controlling log verbosity​

You can control which metadata events are logged using the delta_lake_log_metadata setting.

To log all metadata used in the current query:

SELECT * FROM my_delta_table SETTINGS delta_lake_log_metadata = 1;

SYSTEM FLUSH LOGS delta_lake_metadata_log;

SELECT *
FROM system.delta_lake_metadata_log
WHERE query_id = '{previous_query_id}';

Columns​

  • hostname (LowCardinality(String)) — Hostname of the server executing the query.
  • event_date (Date) — Date of the entry.
  • event_time (DateTime) — Event time.
  • query_id (String) — Query id.
  • table_path (String) — Table path.
  • file_path (String) — File path.
  • content (String) — Content in a JSON format.