SERVER-64737 dbcheck.js should tolerate non-deterministic batch boundaries

2 files changed, 10 insertions, 7 deletions

diff --git a/jstests/replsets/dbcheck.js b/jstests/replsets/dbcheck.js
index 92d14f9e675..e6ddd119632 100644
--- a/jstests/replsets/dbcheck.js
+++ b/jstests/replsets/dbcheck.js
@@ -306,13 +306,16 @@ function testDbCheckParameters() {
 
             assert(keyBoundsResult.hasNext(), "dbCheck put no batches in health log");
 
-            let bounds = keyBoundsResult.next();
+            const bounds = keyBoundsResult.next();
+            const counts = healthLogCounts(healthlog);
             assert.eq(bounds.minKey, start, "dbCheck minKey field incorrect");
-            assert.eq(bounds.maxKey, end, "dbCheck maxKey field incorrect");
 
-            let counts = healthLogCounts(healthlog);
-            assert.eq(counts.totalDocs, end - start);
-            assert.eq(counts.totalBytes, (end - start) * docSize);
+            // dbCheck evaluates some exit conditions like maxCount and maxBytes at batch boundary.
+            // The batch boundary isn't generally deterministic (e.g. can be time-dependent per
+            // maxBatchTimeMillis) hence the greater-than-or-equal comparisons.
+            assert.gte(bounds.maxKey, end, "dbCheck maxKey field incorrect");
+            assert.gte(counts.totalDocs, end - start);
+            assert.gte(counts.totalBytes, (end - start) * docSize);
         });
     }
 
diff --git a/src/mongo/db/commands/dbcheck.cpp b/src/mongo/db/commands/dbcheck.cpp
index 291b79740ac..c26b09d8831 100644
--- a/src/mongo/db/commands/dbcheck.cpp
+++ b/src/mongo/db/commands/dbcheck.cpp
@@ -659,8 +659,8 @@ public:
                "Invoke with { dbCheck: <collection name/uuid>,\n"
                "              minKey: <first key, exclusive>,\n"
                "              maxKey: <last key, inclusive>,\n"
-               "              maxCount: <max number of docs>,\n"
-               "              maxSize: <max size of docs>,\n"
+               "              maxCount: <try to keep a batch within maxCount number of docs>,\n"
+               "              maxSize: <try to keep a batch withing maxSize of docs (bytes)>,\n"
                "              maxCountPerSecond: <max rate in docs/sec>\n"
                "              maxDocsPerBatch: <max number of docs/batch>\n"
                "              maxBytesPerBatch: <try to keep a batch within max bytes/batch>\n"