How to Trace Databend

Tracing In Databend

Databend using Rust's tracing ecosystem tokio-tracing to do log and profile.

Databend default log level is INFO.

Enable Tracing

LOG_LEVEL=DEBUG ./databend-query

If we want to track the execution of a query:

SET max_threads=1;
SELECT sum(number+1)+1 FROM numbers(10000) WHERE number>0 GROUP BY number%3;

Tracing log

note

Databend uses tokio-tracing to trace logs, where the default timezone is UTC and cannot be changed through the Databend timezone setting, therefore the time in the traced log will always be in UTC, and not reflect your local time.

[2021-06-10T08:40:36Z DEBUG clickhouse_srv::cmd] Got packet Query(QueryRequest { query_id: "bac2b254-6245-4cae-910d-3e5e979c8b68", client_info: QueryClientInfo { query_kind: 1, initial_user: "", initial_query_id: "", initial_address: "0.0.0.0:0", interface: 1, os_user: "bohu", client_hostname: "thinkpad", client_name: "ClickHouse ", client_version_major: 21, client_version_minor: 4, client_version_patch: 6, client_revision: 54447, http_method: 0, http_user_agent: "", quota_key: "" }, stage: 2, compression: 1, query: "SELECT sum(number+1)+1 from numbers(10000) where number>0 group by number%3;" })
Jun 10 16:40:36.131 DEBUG ThreadId(16) databend_query::sql::plan_parser: query="SELECT sum(number+1)+1 from numbers(10000) where number>0 group by number%3;"
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] parsing expr
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] parsing expr
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] prefix: Identifier(Ident { value: "number", quote_style: None })
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() Plus
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 30
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] parsing expr
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] prefix: Value(Number("1", false))
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() RParen
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 0
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() RParen
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 0
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] prefix: Function(Function { name: ObjectName([Ident { value: "sum", quote_style: None }]), args: [Unnamed(BinaryOp { left: Identifier(Ident { value: "number", quote_style: None }), op: Plus, right: Value(Number("1", false)) })], over: None, distinct: false })
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() Plus
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 30
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] parsing expr
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] prefix: Value(Number("1", false))
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() Word(Word { value: "from", quote_style: None, keyword: FROM })
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 0
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() Word(Word { value: "from", quote_style: None, keyword: FROM })
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 0
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] parsing expr
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] prefix: Value(Number("10000", false))
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() RParen
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 0
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] parsing expr
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] prefix: Identifier(Ident { value: "number", quote_style: None })
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() Gt
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 20
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] parsing expr
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] prefix: Value(Number("0", false))
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() Word(Word { value: "group", quote_style: None, keyword: GROUP })
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 0
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() Word(Word { value: "group", quote_style: None, keyword: GROUP })
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 0
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] parsing expr
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] prefix: Identifier(Ident { value: "number", quote_style: None })
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() Mod
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 40
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] parsing expr
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] prefix: Value(Number("3", false))
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() SemiColon
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 0
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] get_next_precedence() SemiColon
[2021-06-10T08:40:36Z DEBUG sqlparser::parser] next precedence: 0
Jun 10 16:40:36.135  INFO ThreadId(16) sql_statement_to_plan: databend_query::sql::plan_parser: new
Jun 10 16:40:36.136  INFO ThreadId(16) sql_statement_to_plan: databend_query::sql::plan_parser: enter
Jun 10 16:40:36.136  INFO ThreadId(16) sql_statement_to_plan:select_to_plan: databend_query::sql::plan_parser: new
Jun 10 16:40:36.136  INFO ThreadId(16) sql_statement_to_plan:select_to_plan: databend_query::sql::plan_parser: enter
Jun 10 16:40:36.139  INFO ThreadId(16) sql_statement_to_plan:select_to_plan: databend_query::sql::plan_parser: exit
Jun 10 16:40:36.139  INFO ThreadId(16) sql_statement_to_plan:select_to_plan: databend_query::sql::plan_parser: close time.busy=2.65ms time.idle=457µs
Jun 10 16:40:36.139  INFO ThreadId(16) sql_statement_to_plan: databend_query::sql::plan_parser: exit
Jun 10 16:40:36.139  INFO ThreadId(16) sql_statement_to_plan: databend_query::sql::plan_parser: close time.busy=3.57ms time.idle=453µs
Jun 10 16:40:36.140  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::interpreters::interpreter_select: new
Jun 10 16:40:36.141  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::interpreters::interpreter_select: enter
Jun 10 16:40:36.141 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::optimizers::optimizer: Before ProjectionPushDown
Projection: (sum((number + 1)) + 1):UInt64
  Expression: (sum((number + 1)) + 1):UInt64 (Before Projection)
    AggregatorFinal: groupBy=[[(number % 3)]], aggr=[[sum((number + 1))]]
      AggregatorPartial: groupBy=[[(number % 3)]], aggr=[[sum((number + 1))]]
        Expression: (number % 3):UInt8, (number + 1):UInt64 (Before GroupBy)
          Filter: (number > 0)
            ReadDataSource: scan partitions: [1], scan schema: [number:UInt64], statistics: [read_rows: 10000, read_bytes: 80000]
Jun 10 16:40:36.142 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::optimizers::optimizer: After ProjectionPushDown
Projection: (sum((number + 1)) + 1):UInt64
  Expression: (sum((number + 1)) + 1):UInt64 (Before Projection)
    AggregatorFinal: groupBy=[[(number % 3)]], aggr=[[sum((number + 1))]]
      AggregatorPartial: groupBy=[[(number % 3)]], aggr=[[sum((number + 1))]]
        Expression: (number % 3):UInt8, (number + 1):UInt64 (Before GroupBy)
          Filter: (number > 0)
            ReadDataSource: scan partitions: [1], scan schema: [number:UInt64], statistics: [read_rows: 10000, read_bytes: 80000]
Jun 10 16:40:36.142 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::optimizers::optimizer: Before Scatters
Projection: (sum((number + 1)) + 1):UInt64
  Expression: (sum((number + 1)) + 1):UInt64 (Before Projection)
    AggregatorFinal: groupBy=[[(number % 3)]], aggr=[[sum((number + 1))]]
      AggregatorPartial: groupBy=[[(number % 3)]], aggr=[[sum((number + 1))]]
        Expression: (number % 3):UInt8, (number + 1):UInt64 (Before GroupBy)
          Filter: (number > 0)
            ReadDataSource: scan partitions: [1], scan schema: [number:UInt64], statistics: [read_rows: 10000, read_bytes: 80000]
Jun 10 16:40:36.143 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::optimizers::optimizer: After Scatters
Projection: (sum((number + 1)) + 1):UInt64
  Expression: (sum((number + 1)) + 1):UInt64 (Before Projection)
    AggregatorFinal: groupBy=[[(number % 3)]], aggr=[[sum((number + 1))]]
      AggregatorPartial: groupBy=[[(number % 3)]], aggr=[[sum((number + 1))]]
        Expression: (number % 3):UInt8, (number + 1):UInt64 (Before GroupBy)
          Filter: (number > 0)
            ReadDataSource: scan partitions: [1], scan schema: [number:UInt64], statistics: [read_rows: 10000, read_bytes: 80000]
Jun 10 16:40:36.143  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}:reschedule: databend_query::interpreters::plan_scheduler: new
Jun 10 16:40:36.143  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}:reschedule: databend_query::interpreters::plan_scheduler: enter
Jun 10 16:40:36.143  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}:reschedule: databend_query::interpreters::plan_scheduler: exit
Jun 10 16:40:36.143  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}:reschedule: databend_query::interpreters::plan_scheduler: close time.busy=145µs time.idle=264µs
Jun 10 16:40:36.144  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}:build: databend_query::pipelines::processors::pipeline_builder: new
Jun 10 16:40:36.144  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}:build: databend_query::pipelines::processors::pipeline_builder: enter
Jun 10 16:40:36.144 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}:build: databend_query::pipelines::processors::pipeline_builder: Received plan:
Projection: (sum((number + 1)) + 1):UInt64
  Expression: (sum((number + 1)) + 1):UInt64 (Before Projection)
    AggregatorFinal: groupBy=[[(number % 3)]], aggr=[[sum((number + 1))]]
      AggregatorPartial: groupBy=[[(number % 3)]], aggr=[[sum((number + 1))]]
        Expression: (number % 3):UInt8, (number + 1):UInt64 (Before GroupBy)
          Filter: (number > 0)
            ReadDataSource: scan partitions: [1], scan schema: [number:UInt64], statistics: [read_rows: 10000, read_bytes: 80000]
Jun 10 16:40:36.145 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}:build: databend_query::pipelines::processors::pipeline_builder: Pipeline:
ProjectionTransform × 1 processor
  ExpressionTransform × 1 processor
    GroupByFinalTransform × 1 processor
      GroupByPartialTransform × 1 processor
        ExpressionTransform × 1 processor
          FilterTransform × 1 processor
            SourceTransform × 1 processor
Jun 10 16:40:36.145  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}:build: databend_query::pipelines::processors::pipeline_builder: exit
Jun 10 16:40:36.145  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}:build: databend_query::pipelines::processors::pipeline_builder: close time.busy=1.07ms time.idle=215µs
Jun 10 16:40:36.145 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::pipelines::transforms::transform_projection: execute...
Jun 10 16:40:36.145 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::pipelines::transforms::transform_groupby_final: execute...
Jun 10 16:40:36.146 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::pipelines::transforms::transform_groupby_partial: execute...
Jun 10 16:40:36.146 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::pipelines::transforms::transform_source: execute, table:system.numbers, is_remote:false...
Jun 10 16:40:36.148 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::pipelines::transforms::transform_filter: execute...
Jun 10 16:40:36.148 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::pipelines::transforms::transform_expression_executor: (filter executor) execute, actions: [Input(ActionInput { name: "number", return_type: UInt64 }), Constant(ActionConstant { name: "0", value: 0 }), Function(ActionFunction { name: "(number > 0)", func_name: ">", return_type: Boolean, is_aggregated: false, arg_names: ["number", "0"], arg_types: [UInt64, UInt64], arg_fields: [] })]
Jun 10 16:40:36.150 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::pipelines::transforms::transform_filter: Filter cost: 1.678104ms
Jun 10 16:40:36.150 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::pipelines::transforms::transform_expression_executor: (expression executor) execute, actions: [Input(ActionInput { name: "number", return_type: UInt64 }), Constant(ActionConstant { name: "3", value: 3 }), Function(ActionFunction { name: "(number % 3)", func_name: "%", return_type: UInt64, is_aggregated: false, arg_names: ["number", "3"], arg_types: [UInt64, UInt64], arg_fields: [] }), Input(ActionInput { name: "number", return_type: UInt64 }), Constant(ActionConstant { name: "1", value: 1 }), Function(ActionFunction { name: "(number + 1)", func_name: "+", return_type: UInt64, is_aggregated: false, arg_names: ["number", "1"], arg_types: [UInt64, UInt64], arg_fields: [] })]
Jun 10 16:40:36.165 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::pipelines::transforms::transform_groupby_partial: Group by partial cost: 18.822193ms
Jun 10 16:40:36.166 DEBUG ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::pipelines::transforms::transform_groupby_final: Group by final cost: 20.170851ms
Jun 10 16:40:36.167  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::interpreters::interpreter_select: exit
Jun 10 16:40:36.167  INFO ThreadId(309) execute{ctx.id="1c651744-3e73-4b94-9df0-dc031b73c626"}: databend_query::interpreters::interpreter_select: close time.busy=26.1ms time.idle=592µs
Jun 10 16:40:36.167 DEBUG ThreadId(309) databend_query::pipelines::transforms::transform_expression_executor: (expression executor) execute, actions: [Input(ActionInput { name: "sum((number + 1))", return_type: UInt64 }), Constant(ActionConstant { name: "1", value: 1 }), Function(ActionFunction { name: "(sum((number + 1)) + 1)", func_name: "+", return_type: UInt64, is_aggregated: false, arg_names: ["sum((number + 1))", "1"], arg_types: [UInt64, UInt64], arg_fields: [] })]
Jun 10 16:40:36.168 DEBUG ThreadId(309) databend_query::pipelines::transforms::transform_expression_executor: (projection executor) execute, actions: [Input(ActionInput { name: "(sum((number + 1)) + 1)", return_type: UInt64 })]
Jun 10 16:40:36.168 DEBUG ThreadId(309) databend_query::pipelines::transforms::transform_projection: Projection cost: 241.864µs

Explore and Diagnose with tokio-console

tokio-console is a diagnostics and debugging tool for asynchronous Rust programs. Make sure you have the tool installed before you use it.

Steps

Compile with specific RUSTFLAGS and features. We can use --bin to specify binary.
```
RUSTFLAGS="--cfg tokio_unstable" cargo build --features tokio-console
```
Run databend-meta or/and databend-query, remembering to set the log level of the program you need to diagnose to TRACE.
```
LOG_LEVEL=TRACE databend-query # for query
```
or
```
databend-meta --single --log-level=TRACE # for meta
```

Run tokio-console.

tokio-console # default connection: http://127.0.0.1:6669

Tips

Note that tokio-console only supports diagnostics for a single program at a time, so please ensure that only one program has a log level of TRACE. Otherwise, only the first program to occupy the port will be monitored.

If you need to diagnose multiple programs at the same time, consider using TOKIO_CONSOLE_BIND to assign different binds, for example:

TOKIO_CONSOLE_BIND=127.0.0.1:16667 LOG_LEVEL=TRACE target/debug/databend-query
tokio-console http://127.0.0.1:16667 # for query console, http://127.0.0.1:16667
databend-meta --single --log-level=TRACE
tokio-console # for meta console, http://127.0.0.1:6669

Examples

databend-query

databend-meta

task in console

How to Trace Databend

Tracing In Databend

Enable Tracing

Tracing log

Explore and Diagnose with tokio-console

Steps

Tips

Examples

Join our growing community

GitHub

Slack

Twitter

YouTube

Tracing In Databend​

Enable Tracing​

Tracing log​

Explore and Diagnose with tokio-console​

Steps​

Tips​

Examples​

Join our growing community

GitHub

Slack

Twitter

YouTube

Tracing In Databend

Enable Tracing

Tracing log

Explore and Diagnose with tokio-console

Steps

Tips

Examples