ClickHouse/docs/en/operations/system-tables/symbols.md
2023-11-10 01:47:00 +03:00

36 lines
2.7 KiB
Markdown

---
slug: /en/operations/system-tables/symbols
---
# symbols
Contains information for introspection of `clickhouse` binary. It requires the introspection privilege to access.
This table is only useful for C++ experts and ClickHouse engineers.
Columns:
- `symbol` ([String](../../sql-reference/data-types/string.md)) — Symbol name in the binary. It is mangled. You can apply `demangle(symbol)` to obtain a readable name.
- `address_begin` ([UInt64](../../sql-reference/data-types/int-uint.md)) — Start address of the symbol in the binary.
- `address_end` ([UInt64](../../sql-reference/data-types/int-uint.md)) — End address of the symbol in the binary.
- `name` ([String](../../sql-reference/data-types/string.md)) — Alias for `event`.
**Example**
``` sql
SELECT address_begin, address_end - address_begin AS size, demangle(symbol) FROM system.symbols ORDER BY size DESC LIMIT 10
```
``` text
┌─address_begin─┬─────size─┬─demangle(symbol)──────────────────────────────────────────────────────────────────┐
│ 25000976 │ 29466000 │ icudt70_dat │
│ 400605288 │ 2097272 │ arena_emap_global │
│ 18760592 │ 1048576 │ CLD2::kQuadChrome1015_2 │
│ 9807152 │ 884808 │ TopLevelDomainLookupHash::isValid(char const*, unsigned long)::wordlist │
│ 57442432 │ 850608 │ llvm::X86Insts │
│ 55682944 │ 681360 │ (anonymous namespace)::X86DAGToDAGISel::SelectCode(llvm::SDNode*)::MatcherTable │
│ 55130368 │ 502840 │ (anonymous namespace)::X86InstructionSelector::getMatchTable() const::MatchTable0 │
│ 402930616 │ 404032 │ qpl::ml::dispatcher::hw_dispatcher::get_instance()::instance │
│ 274131872 │ 356795 │ DB::SettingsTraits::Accessor::instance()::$_0::operator()() const │
│ 58293040 │ 249424 │ llvm::X86InstrNameData │
└───────────────┴──────────┴───────────────────────────────────────────────────────────────────────────────────┘
```