Debugging and Reporting Environment Questions (FireDAC)

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This topic contains a list of questions and answers related to the debugging and reporting environment.

Q1: How can I obtain Client/Session info like FDExplorer?

A: See DBMS Environment Reports.

Q2: How can I generate trace/monitor output?

A: See Tracing and Monitoring.

Q3: How can I temporarily enable/disable trace/monitor output?

A: Use TFDMoniXxxxClientLink.Tracing. It enables or disables tracing output for a specific tracer kind. Also, to enable or disable trace output for a specific established connection, use FDConnection.ConnectionIntf.Tracing.

Q4: What is the meaning of EventKind?

A: Please see the list below:

  • LiveCycle: Object creation/destruction. For example, IFDPhysConnection is created.
  • Error: DBMS errors.
  • ConnConnect: Connection open/close.
  • ConnTransact: Start/Commit/Rollback.
  • ConnService: Some special events.
  • CmdPrepare: IFDPhysCommand.Prepare calls.
  • CmdExecute: IFDPhysCommand.Execute or Open calls.
  • CmdDataIn: Command parameter values.
  • CmdDataOut: Result set rows.
  • AdaptUpdat: All about posting updates.
  • Vendor: The low-level DBMS API calls.
  • Component: Some high-level events.

Q5: In which unit and in which part of the code can I view the SQL statement if I need to do some debugging?

A: You can do that using one of the following options:

  • You can use MonitorBy connection parameter.
  • Open FireDAC.Phys.pas, find the TFDPhysCommand.Prepare method and there is the InternalPrepare method call. Set a breakpoint there and check the value of the FDbCommandText field. It is the SQL command text, as it will be sent to a DBMS.

Q6: How can I get the final SQL statement with all the parameters and macros replaced?

A: See TFDQuery.Text. Note that FireDAC does not substitute parameter values into the final SQL command text.

Q7: I enabled trace output and I am getting constant Access Violations. What is wrong? Is it a bug?

A: FireDAC for the ODBC based drivers uses the Microsoft ODBC driver manager tracing facilities. To generate the trace output, the manager internally uses C RTL functions IsBadReadPtr/IsBadWritePtr, which can generate a controlled AV internally. The exception will not be propagated outside the manager, but the IDE debugger stops on it. Just ignore them.

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