QUERY

The text of the traced statement.

TRACE

The trace, in  JSON format.

MISSING_BYTES_BEYOND_MAX_MEM_SIZE

Each remembered trace is a string that is extended as optimization progresses and appends data to it. The  optimizer_trace_max_mem_size  variable sets a limit on the total amount of memory used by all currently remembered traces. If this limit is reached, the current trace is not extended (and thus is incomplete), and the  MISSING_BYTES_BEYOND_MAX_MEM_SIZE column shows the number of bytes missing from the trace.

INSUFFICIENT_PRIVILEGES

If a traced query uses views or stored routines that have  SQL SECURITY with a value of  DEFINER, it may be that a user other than the definer is denied from seeing the trace of the query. In that case, the trace is shown as empty and  INSUFFICIENT_PRIVILEGES has a value of 1. Otherwise, the value is 0.