SQL Trace

SQL Trace is a set of functional tools provided by DolphinDB. It allows users to analyze the internal execution time of complex SQL queries by tracing the step-by-step execution process of SQL scripts. This capability helps users identify performance bottlenecks and optimize query efficiency.

The setTraceMode function is used to enable or disable SQL tracing. A complete tracing process must start with setTraceMode(true) and end with setTraceMode(false). Note that DolphinDB begins tracing from the first request received after enabling tracing. Therefore, the setTraceMode command must be executed separately from the statements to be traced.

After enabling tracing, you can call getTraces to retrieve a table containing trace information. This table records the timestamps when the client sends the script to the server, the scripts sent to the server for execution, the trace IDs, and the ID of the sessions that initiates the tracing.

For example, the following script demonstrates a complete tracing process:

setTraceMode(true)
go
select * from loadTable("dfs://S_SEC_INFO", "S_SEC_INFO")
setTraceMode(false)

The getTraces() function is used to obtain the trace information. The result is show in the following figure.

The viewTraceInfo(traceId, [isTreeView = true]) function is used to display the trace details for a specific trace ID. For example, to view the trace details for the SQL statement executed above, you can use the following command:

viewTraceInfo("2eb58830-90cd-e3b3-4544-429237e80ad8")

The following figure presents the SQL execution process in a tree structure and details the execution time for each step.