DBA_HIST_INTERCONNECT_PINGS

DBA_HIST_INTERCONNECT_PINGS displays information about measured latency of interconnect messages (round-trip) from instance to instance. In Oracle Database 11g, the PING process assesses the latencies associated with communications for each pair of instances.

Every few seconds, the process in one instance (INSTANCE_NUMBER value) sends two messages to each instance (TARGET_INSTANCE value). One message has a size of 500 bytes and the other has a size of 8 KB. The message is received by the PING process on the target instance and is immediately acknowledged. The time for the round-trip is measured and collected.

Column	Datatype	NULL	Description
`SNAP_ID`	`NUMBER`	`NOT NULL`	Unique snapshot ID
`DBID`	`NUMBER`	`NOT NULL`	Database ID for the snapshot
`INSTANCE_NUMBER`	`NUMBER`	`NOT NULL`	Instance number for the snapshot
`TARGET_INSTANCE`	`NUMBER`	`NOT NULL`	Target instance number
`CNT_500B`	`NUMBER`		Number of pings of size 500 bytes from `INSTANCE_NUMBER` to `TARGET_INSTANCE` since the startup of the source instance (`INSTANCE_NUMBER`)
`WAIT_500B`	`NUMBER`		Sum of round-trip times for messages of size 500 bytes from `INSTANCE_NUMBER` to `TARGET_INSTANCE` since the startup of the source instance (`INSTANCE_NUMBER`). Dividing by `CNT_500B` gives the average latency.
`WAITSQ_500B`	`NUMBER`		Sum of squares (divided by 1000) of round-trip times for messages of size 500 bytes from `INSTANCE_NUMBER` to `TARGET_INSTANCE` since the startup of the source instance (`INSTANCE_NUMBER`). When used with `CNT_500B` and `WAIT_500B`, the standard deviation of the latency can be calculated.
`CNT_8K`	`NUMBER`		Number of pings of size 8 KB from `INSTANCE_NUMBER` to `TARGET_INSTANCE` since the startup of the source instance (`INSTANCE_NUMBER`)
`WAIT_8K`	`NUMBER`		Sum of round-trip times for messages of size 8 KB from `INSTANCE_NUMBER` to `TARGET_INSTANCE` since the startup of the source instance (`INSTANCE_NUMBER`). Dividing by `CNT_8K` gives the average latency.
`WAITSQ_8K`	`NUMBER`		Sum of squares (divided by 1000) of round-trip times for messages of size 8 KB from `INSTANCE_NUMBER` to `TARGET_INSTANCE` since the startup of the source instance (`INSTANCE_NUMBER`). When used with `CNT_8K` and `WAIT_8K`, the standard deviation of the latency can be calculated.