TRACE

The TRACE statement provides detailed information about query execution. It is intended to be viewed through a Graphical interface exposed by the TiDB server’s status port.

Synopsis

TraceStmt

TRACE - 图1

TracableStmt

TRACE - 图2

  1. TraceStmt ::=
  2.     "TRACE" ( "FORMAT" "=" stringLit )? TracableStmt
  4. TracableStmt ::=
  5.     ( SelectStmt | DeleteFromStmt | UpdateStmt | InsertIntoStmt | ReplaceIntoStmt | UnionStmt | LoadDataStmt | BeginTransactionStmt | CommitStmt | RollbackStmt | SetStmt )
FormatDescription
rowOutput in a tree format
jsonStructured output in JSON format
logLog based output

Examples

Row

  1. TRACE FORMAT='row' SELECT * FROM mysql.user;
  1. +--------------------------------------------+-----------------+------------+
  2. | operation                                  | startTS         | duration   |
  3. +--------------------------------------------+-----------------+------------+
  4. | trace                                      | 17:03:31.938237 | 886.086µs  |
  5. |   ├─session.Execute                        | 17:03:31.938247 | 507.812µs  |
  6. |   │ ├─session.ParseSQL                     | 17:03:31.938254 | 22.504µs   |
  7. |   │ ├─executor.Compile                     | 17:03:31.938321 | 278.931µs  |
  8. |   │ │ └─session.getTxnFuture               | 17:03:31.938337 | 1.515µs    |
  9. |   │ └─session.runStmt                      | 17:03:31.938613 | 109.578µs  |
  10. |   │   ├─TableReaderExecutor.Open           | 17:03:31.938645 | 50.657µs   |
  11. |   │   │ └─distsql.Select                   | 17:03:31.938666 | 21.066µs   |
  12. |   │   │   └─RPCClient.SendRequest          | 17:03:31.938799 | 158.411µs  |
  13. |   │   └─session.CommitTxn                  | 17:03:31.938705 | 12.06µs    |
  14. |   │     └─session.doCommitWitRetry         | 17:03:31.938709 | 2.437µs    |
  15. |   ├─*executor.TableReaderExecutor.Next     | 17:03:31.938781 | 224.327µs  |
  16. |   └─*executor.TableReaderExecutor.Next     | 17:03:31.939019 | 6.266µs    |
  17. +--------------------------------------------+-----------------+------------+
  18. 13 rows in set (0.00 sec)

JSON

  1. TRACE FORMAT='json' SELECT * FROM mysql.user;

The JSON formatted trace can be pasted into the trace viewer, which is accessed via the TiDB status port:

TiDB Trace Viewer-1

TiDB Trace Viewer-2

Log

  1. TRACE FORMAT='log' SELECT * FROM mysql.user;
  1. +----------------------------+--------------------------------------------------------+------+------------------------------------+
  2. | time                       | event                                                  | tags | spanName                           |
  3. +----------------------------+--------------------------------------------------------+------+------------------------------------+
  4. | 2024-04-08 08:41:47.358734 | --- start span trace ----                              |      | trace                              |
  5. | 2024-04-08 08:41:47.358737 | --- start span session.ExecuteStmt ----                |      | session.ExecuteStmt                |
  6. | 2024-04-08 08:41:47.358746 | --- start span executor.Compile ----                   |      | executor.Compile                   |
  7. | 2024-04-08 08:41:47.358984 | --- start span session.runStmt ----                    |      | session.runStmt                    |
  8. | 2024-04-08 08:41:47.359035 | --- start span TableReaderExecutor.Open ----           |      | TableReaderExecutor.Open           |
  9. | 2024-04-08 08:41:47.359047 | --- start span distsql.Select ----                     |      | distsql.Select                     |
  10. | 2024-04-08 08:41:47.359073 | --- start span *executor.TableReaderExecutor.Next ---- |      | *executor.TableReaderExecutor.Next |
  11. | 2024-04-08 08:41:47.359077 | table scan table: user, range: [[-inf,+inf]]           |      | *executor.TableReaderExecutor.Next |
  12. | 2024-04-08 08:41:47.359094 | --- start span regionRequest.SendReqCtx ----           |      | regionRequest.SendReqCtx           |
  13. | 2024-04-08 08:41:47.359098 | send Cop request to region 16 at store1                |      | regionRequest.SendReqCtx           |
  14. | 2024-04-08 08:41:47.359237 | --- start span *executor.TableReaderExecutor.Next ---- |      | *executor.TableReaderExecutor.Next |
  15. | 2024-04-08 08:41:47.359240 | table scan table: user, range: [[-inf,+inf]]           |      | *executor.TableReaderExecutor.Next |
  16. | 2024-04-08 08:41:47.359242 | execute done, ReturnRow: 1, ModifyRow: 0               |      | trace                              |
  17. | 2024-04-08 08:41:47.359252 | execute done, modify row: 0                            |      | trace                              |
  18. +----------------------------+--------------------------------------------------------+------+------------------------------------+
  19. 14 rows in set (0.0008 sec)

MySQL compatibility

This statement is a TiDB extension to MySQL syntax.

See also