DBA_HIST_LATCH

DBA_HIST_LATCH displays historical aggregate latch statistics for both parent and child latches, grouped by latch name. This view contains snapshots of V$LATCH.

Column	Datatype	Description
`SNAP_ID`	`NUMBER`	Unique snapshot ID
`DBID`	`NUMBER`	Database ID for the snapshot
`INSTANCE_NUMBER`	`NUMBER`	Instance number for the snapshot
`LATCH_HASH`	`NUMBER`	Latch Hash
`LATCH_NAME`	`VARCHAR2(64)`	Latch name
`LEVEL#`	`NUMBER`	Latch level
`GETS`	`NUMBER`	Number of times the latch was requested in willing-to-wait mode
`MISSES`	`NUMBER`	Number of times the latch was requested in willing-to-wait mode and the requestor had to wait
`SLEEPS`	`NUMBER`	Number of times a willing-to-wait latch request resulted in a session sleeping while waiting for the latch
`IMMEDIATE_GETS`	`NUMBER`	Number of times a latch was requested in no-wait mode
`IMMEDIATE_MISSES`	`NUMBER`	Number of times a no-wait latch request did not succeed (that is, missed)
`SPIN_GETS`	`NUMBER`	Number of willing-to-wait latch requests which missed the first try but succeeded while spinning
`SLEEP[1 \| 2 \| 3 \| 4]`	`NUMBER`	These columns have been deprecated and are present only for compatibility with previous releases of Oracle. No data is accumulated for thse columns; they will always have a value of zero.
`WAIT_TIME`	`NUMBER`	Elapsed time spent waiting for the latch (in microseconds)