Meta Counter Group

Counts internal statistics of every other counter group (keys in memory, new keys, flush time), keyed by that group's GUID.

Property	Value
GUID	`{4D88CC23-2883-4DEA-A313-A23B60FE8BDA}`
Layer	System
Input	Internal
Key type	Counter group GUID
Implementation	Native C++ — CPICGCounterMons (trisul_probe/src/sysplugs/monitors/PICGCounterMons.cpp) defines the group; values come from CXCounterGroup::GenMonitorTMS (stengine/XCounterGroup.cpp)
Bucket / Topper	60 s / 300 s
Enabled by default	Yes

What it measures

At the end of each flush, every counter group writes one row about itself to its own key in this group.
A group that has never been updated since the probe started writes nothing.
This group and Meta Session Group do not report on themselves.
Each stats engine writes its own row for the same key. The counter meters add up across engines.
For Internal Hosts ({889900CC-0063-11A5-8380-FEBDBABBDBEA}), meters 0 and 1 count only hosts with Transmit bytes in the current or previous bucket. This keeps scanned but unused internal IPs out of the count.

One key is the GUID of the counter group being monitored. The label is the group name.

Key	Meaning
`SYS:GROUP_TOTALS`	Sum of every update in the interval: the total across all monitored groups, for example all keys in memory across the probe.

ID	Name	Type	Units	Top	Bottom	Description
0	Master Size	VT_COUNTER	keys	0	0	Keys held in memory for the group.
1	MRU Size	VT_COUNTER	keys	0	0	Keys in the most-recently-used index. Equal to Master Size in normal operation.
2	Pending KU Size	VT_COUNTER	keys	0	0	Key label updates waiting to be sent to the hub.
3	Flush US	VT_GAUGE	usec	0	0	Time taken by the last flush of this group.
4	Flush Keys	VT_COUNTER	keys	0	0	Keys written in the last flush.
5	New Keys	VT_COUNTER	hits	0	0	Keys created in the interval.
6	Key Hits	VT_COUNTER	hits	0	0	Updates that found an existing key.
7	Unique Keys	VT_COUNTER	keys	0	0	Distinct keys updated in the interval (HyperLogLog estimate).
8	Heap mem	VT_GAUGE	B	0	0	Not populated by the current code (always 0).
9	Tail Prunes	VT_COUNTER	hits	0	0	Least-recently-used keys dropped in the interval. Keys are dropped when the group goes over its high-water key count and is trimmed back to the low-water count.
10	Hi Water Rej	VT_COUNTER	hits	0	0	New keys refused in the interval. Only crosskey groups refuse keys; their updates still go to `SYS:GROUP_TOTALS`. Always 0 for other groups.
11	Unused Cardinality counter	VT_GAUGE	Uniques	20	20	Reserved cardinality slot. Not populated.
12	Unused Cardinality counter	VT_GAUGE	Uniques	20	20	Reserved cardinality slot. Not populated.