DOCS-16015 Add SBE Plan Cache Metrics to Server Status Page (#4124)

* DOCS-16015 Add SBE Plan Cache Metrics to Server Status Page

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* IR feedback

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* Apply suggestions from code review

Co-authored-by: Ashley Brown <[email protected]>

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Co-authored-by: Ashley Brown <[email protected]>

Author: ianf-mongodb

source/reference/command/serverStatus.txt

@@ -1698,6 +1698,10 @@ metrics
                ]
             }
          },
+         planCache: {
+            classic: { hits: Long("<num>"), misses: Long("<num>") },
+            sbe: { hits: Long("<num>"), misses: Long("<num>") }
+         },
          queryFramework: {
             aggregate: {
                classicHybrid: Long("<num>"),
@@ -3825,6 +3829,44 @@ oplogTruncation
 
       Available in the :doc:`/core/wiredtiger`.
 
+.. _server-status-planCache:
+
+planCache
+~~~~~~~~~
+
+.. versionadded:: 7.0
+
+.. code-block:: javascript
+
+   planCache: {
+      classic: { hits: Long("<num>"), misses: Long("<num>") },
+      sbe: { hits: Long("<num>"), misses: Long("<num>") }
+   }
+
+.. serverstatus:: planCache
+
+   A document that reports query plan cache statistics.
+
+.. serverstatus:: planCache.classic.hits
+
+   Number of classic execution engine query plans found in the query 
+   cache and reused to avoid the query planning phase.
+
+.. serverstatus:: planCache.classic.misses
+
+   Number of classic execution engine query plans which were not found 
+   in the query cache and went through the query planning phase.
+
+.. serverstatus:: planCache.sbe.hits
+
+   Number of slot-based execution engine query plans found in the query 
+   cache and reused to avoid the query planning phase.
+
+.. serverstatus:: planCache.sbe.misses
+
+   Number of slot-based execution engine query plans which were not found 
+   in the query cache and went through the query planning phase.
+
 .. _server-status-readConcernCounters:
 
 readConcernCounters

source/release-notes/7.0.txt

@@ -324,6 +324,15 @@ on ``mongos`` for every operation that used collection routing
 information even if the operation wasn't blocked by a catalog refresh
 activity. 
 
+``serverStatus`` Output Change
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+:dbcommand:`serverStatus` includes the following new fields in its
+output:
+
+Plan Cache Metrics
+  - :serverstatus:`planCache`
+
 .. _7.0-rapid-release-changes:
 
 Changes Introduced in 6.X-Series Rapid Releases