SERVER-74507 Gracefully handle empty time-series options in collModr6.3.0-rc1

(cherry picked from commit 5035fde474f8aadfd50dc39d8a6e8619d97cb33f)

3 files changed, 33 insertions, 0 deletions

diff --git a/jstests/core/timeseries/timeseries_collmod.js b/jstests/core/timeseries/timeseries_collmod.js
index 2d4888690e3..18ae48a421f 100644
--- a/jstests/core/timeseries/timeseries_collmod.js
+++ b/jstests/core/timeseries/timeseries_collmod.js
@@ -211,5 +211,8 @@ if (TimeseriesTest.timeseriesScalabilityImprovementsEnabled(db.getMongo())) {
         "timeseries":
             {"bucketMaxSpanSeconds": bucketingValueMax, "bucketRoundingSeconds": bucketingValueMax}
     }));
+
+    // No-op command should succeed with empty time-series options.
+    assert.commandWorked(db.runCommand({"collMod": collName, "timeseries": {}}));
 }
 })();
diff --git a/jstests/noPassthrough/sharded_timeseries_bucketing_parameters_downgrade.js b/jstests/noPassthrough/sharded_timeseries_bucketing_parameters_downgrade.js
index 4f58f1717c9..0926e372be9 100644
--- a/jstests/noPassthrough/sharded_timeseries_bucketing_parameters_downgrade.js
+++ b/jstests/noPassthrough/sharded_timeseries_bucketing_parameters_downgrade.js
@@ -36,6 +36,11 @@ function useBucketingParametersOnLowerFCV() {
         }
     }));
 
+    // On the latestFCV, we should not be able to use collMod with incomplete bucketing parameters.
+    assert.commandFailedWithCode(
+        db.runCommand({collMod: collName, timeseries: {bucketMaxSpanSeconds: 3600}}),
+        ErrorCodes.InvalidOptions);
+
     // We should fail to downgrade if we have a collection with custom bucketing parameters set.
     assert.commandFailedWithCode(db.adminCommand({setFeatureCompatibilityVersion: lastLTSFCV}),
                                  ErrorCodes.CannotDowngrade);
@@ -66,6 +71,23 @@ function useBucketingParametersOnLowerFCV() {
         timeseries: {bucketMaxSpanSeconds: 3600, bucketRoundingSeconds: 3600}
     }),
                                  ErrorCodes.InvalidOptions);
+    assert.commandFailedWithCode(
+        db.runCommand({collMod: collName, timeseries: {bucketMaxSpanSeconds: 3600}}),
+        ErrorCodes.InvalidOptions);
+    assert.commandFailedWithCode(
+        db.runCommand({collMod: collName, timeseries: {bucketRoundingSeconds: 3600}}),
+        ErrorCodes.InvalidOptions);
+
+    // Verify the time-series options are valid.
+    let collections = assert.commandWorked(db.runCommand({listCollections: 1})).cursor.firstBatch;
+    let collectionEntry = collections.find(entry => entry.name === 'system.buckets.' + collName);
+    assert(collectionEntry);
+
+    assert.eq(collectionEntry.options.timeseries.granularity, "seconds");
+    // Downgrading does not remove the 'bucketMaxSpanSeconds' parameter. It should correspond with
+    // the "seconds" granularity.
+    assert.eq(collectionEntry.options.timeseries.bucketMaxSpanSeconds, 3600);
+    assert.isnull(collectionEntry.options.timeseries.bucketRoundingSeconds);
 }
 
 useBucketingParametersOnLowerFCV();
diff --git a/src/mongo/db/timeseries/timeseries_options.cpp b/src/mongo/db/timeseries/timeseries_options.cpp
index d3d9b3693d0..d384f662a99 100644
--- a/src/mongo/db/timeseries/timeseries_options.cpp
+++ b/src/mongo/db/timeseries/timeseries_options.cpp
@@ -59,6 +59,14 @@ Status isTimeseriesGranularityValidAndUnchanged(const TimeseriesOptions& current
     bool allowSecondsParameters = feature_flags::gTimeseriesScalabilityImprovements.isEnabled(
         serverGlobalParams.featureCompatibility);
 
+    // If the timeseries options are completely empty, we can skip updating them.
+    if (!targetGranularity.has_value() && !targetOptions.getBucketMaxSpanSeconds().has_value() &&
+        !targetOptions.getBucketRoundingSeconds().has_value()) {
+        if (shouldUpdateOptions)
+            *shouldUpdateOptions = false;
+        return Status::OK();
+    }
+
     if (shouldUpdateOptions) {
         *shouldUpdateOptions = true;
     }