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MySQL 9.5 Reference Manual  / ...  / Optimization  / Tracing the Optimizer  /  The optimizer_trace System Variable

10.15.8 The optimizer_trace System Variable

The optimizer_trace system variable has these on/off switches:

  • enabled: Enables (ON) or disables (OFF) tracing

  • one_line: If set toON, the trace contains no whitespace, thus conserving space. This renders the trace difficult to read for humans, still usable by JSON parsers, since they ignore whitespace.