X$KSLED and Enhanced Session Wait Data

Abstract

The X$ fixed table X$KSLED is an undocumented X$ fixed table. The dynamic performance view V$SESSION_WAIT is based on X$KSLED and X$KSUSECST. X$KSLED contributes the wait event name to V$SESSION_WAIT whereas X$KSUSECST holds timing information. Neither Oracle9i nor Oracle 10g have a V$ view that provides more than centisecond resolution for a single wait event at session level.¹ There is also no view that integrates information on operating system processes found in V$PROCESS with wait information. It’s a bit cumbersome to correctly interpret the columns WAIT_TIME and SECONDS_IN_WAIT of the view V$SESSION_WAIT depending on the value of the column STATE.