DBA_HIST_LATCH_CHILDREN displays historical statistics about child latches. This view includes all columns of DBA_HIST_LATCH plus the CHILD# column. Note that child latches have the same parent if their LATCH# columns match each other. This view contains snapshots of V$LATCH_CHILDREN.
| Column | Datatype | NULL | 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 | |
CHILD# |
NUMBER |
Child latch number (unique only to each parent latch) | |
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 | |
SLEEP1 |
NUMBER |
Waits that slept 1 time | |
SLEEP2 |
NUMBER |
Waits that slept 2 times | |
SLEEP3 |
NUMBER |
Waits that slept 3 times | |
SLEEP4 |
NUMBER |
Waits that slept 4 or more times | |
WAIT_TIME |
NUMBER |
Elapsed time spent waiting for the latch (in microseconds) |