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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.

Description

Contains stack traces of all server threads. Allows developers to introspect the server state. To analyze stack frames, use the addressToLine, addressToLineWithInlines, addressToSymbol and demangle introspection functions.

Columns

  • thread_name (String) — The name of the thread.
  • thread_id (UInt64) — The thread identifier
  • query_id (String) — The ID of the query this thread belongs to.
  • trace (Array(UInt64)) — The stacktrace of this thread. Basically just an array of addresses.
  • untracked_memory (Int64) — Per-thread atomic-less counter of memory allocations not yet propagated to the parent MemoryTracker. May be negative if more was freed than allocated since the last flush.

Example

Enabling introspection functions:
Getting symbols from ClickHouse object files:
Getting filenames and line numbers in ClickHouse source code:

See Also

  • Introspection Functions — Which introspection functions are available and how to use them.
  • system.trace_log — Contains stack traces collected by the sampling query profiler.
  • arrayMap) — Description and usage example of the arrayMap function.
  • arrayFilter — Description and usage example of the arrayFilter function.
Last modified on July 2, 2026