system.instrumentation

System table containing the instrumentation points

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

Contains the instrumentation points using LLVM’s XRay feature.

Columns

• id (UInt32) — ID of the instrumentation point
• function_id (Int32) — ID assigned to the function in xray_instr_map section of elf-binary.
• function_name (LowCardinality(String)) — Name used to instrument the function.
• handler (LowCardinality(String)) — Handler that was patched into instrumentation points of the function.
• entry_type (Enum8(‘Entry’ = 0, ‘Exit’ = 1, ‘EntryAndExit’ = 2)) — Entry type for the patch.
• symbol (LowCardinality(String)) — Complete and demangled symbol name.
• arguments (Array(Dynamic)) — Arguments for the handler call.

Example

SELECT * FROM system.instrumentation FORMAT Vertical;

Row 1:
──────
id:            0
function_id:   231280
function_name: QueryMetricLog::startQuery
handler:       log
entry_type:    Entry
symbol:        DB::QueryMetricLog::startQuery(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&, std::__1::chrono::time_point<std::__1::chrono::system_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000l>>>, unsigned long)
arguments:     ['test']

Row 2:
──────
id:            1
function_id:   231280
function_name: QueryMetricLog::startQuery
handler:       profile
entry_type:    EntryAndExit
symbol:        DB::QueryMetricLog::startQuery(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&, std::__1::chrono::time_point<std::__1::chrono::system_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000l>>>, unsigned long)
arguments:     []

Row 3:
──────
id:            2
function_id:   231280
function_name: QueryMetricLog::startQuery
handler:       sleep
entry_type:    Exit
symbol:        DB::QueryMetricLog::startQuery(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&, std::__1::chrono::time_point<std::__1::chrono::system_clock, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000l>>>, unsigned long)
arguments:     [0.3]

3 rows in set. Elapsed: 0.302 sec.

See Also

• SYSTEM INSTRUMENT — Add or remove instrumentation points.
• system.trace_log — Inspect profiling log.
• system.symbols — Inspect symbols to add instrumentation points.