SERVER-61175 Store the original user index definition on the transformed index definition on the buckets collection for partial indexes

6 files changed, 104 insertions, 36 deletions

diff --git a/jstests/core/timeseries/timeseries_index.js b/jstests/core/timeseries/timeseries_index.js
index 0a6bbd6d51a..6cddbdc2ea8 100644
--- a/jstests/core/timeseries/timeseries_index.js
+++ b/jstests/core/timeseries/timeseries_index.js
@@ -4,7 +4,7 @@
  * @tags: [
  *   does_not_support_stepdowns,
  *   does_not_support_transactions,
- *   requires_fcv_51,
+ *   requires_fcv_52,
  *   requires_getmore,
  * ]
  */
@@ -275,10 +275,13 @@ TimeseriesTest.run((insert) => {
                                      [ErrorCodes.CannotCreateIndex, ErrorCodes.InvalidOptions]);
     };
 
-    // Partial indexes are not supported on time-series collections.
-    testCreateIndexFailed({[metaFieldName]: 1}, {partialFilterExpression: {meta: {$gt: 5}}});
-    testCreateIndexFailed({[metaFieldName]: 1},
-                          {partialFilterExpression: {[metaFieldName]: {$gt: 5}}});
+    if (!TimeseriesTest.timeseriesMetricIndexesEnabled(db.getMongo())) {
+        // Partial indexes are not supported on time-series collections if the time-series metric
+        // feature flag is disabled.
+        testCreateIndexFailed({[metaFieldName]: 1}, {partialFilterExpression: {meta: {$gt: 5}}});
+        testCreateIndexFailed({[metaFieldName]: 1},
+                              {partialFilterExpression: {[metaFieldName]: {$gt: 5}}});
+    }
 
     // Unique indexes are not supported on clustered collections.
     testCreateIndexFailed({[metaFieldName]: 1}, {unique: true});
diff --git a/jstests/core/timeseries/timeseries_index_spec.js b/jstests/core/timeseries/timeseries_index_spec.js
index c27354be313..eaf7065d3e9 100644
--- a/jstests/core/timeseries/timeseries_index_spec.js
+++ b/jstests/core/timeseries/timeseries_index_spec.js
@@ -30,48 +30,68 @@ TimeseriesTest.run(() => {
     assert.commandWorked(db.createCollection(
         coll.getName(), {timeseries: {timeField: timeFieldName, metaField: metaFieldName}}));
 
-    assert.commandWorked(coll.createIndex({[timeFieldName]: 1}));
-    assert.commandWorked(coll.createIndex({[metaFieldName]: 1}));
-
-    if (TimeseriesTest.timeseriesMetricIndexesEnabled(db.getMongo())) {
-        assert.commandWorked(coll.createIndex({x: 1}, {name: "x"}));
-    }
-
-    const checkIndexSpec = function(spec, userIndex) {
+    const checkIndexSpec = function(spec, userIndex, isDowngradeCompatible) {
         assert(spec.hasOwnProperty("v"));
         assert(spec.hasOwnProperty("name"));
         assert(spec.hasOwnProperty("key"));
 
         if (userIndex) {
             assert(!spec.hasOwnProperty("originalSpec"));
-
-            if (spec.name == "x") {
-                assert.eq(spec.key, {x: 1});
-            }
-
             return;
         }
 
-        if (spec.name == "x") {
+        if (!isDowngradeCompatible) {
             assert(spec.hasOwnProperty("originalSpec"));
             assert.eq(spec.v, spec.originalSpec.v);
             assert.eq(spec.name, spec.originalSpec.name);
             assert.neq(spec.key, spec.originalSpec.key);
-
-            assert.eq(spec.key, {"control.min.x": 1, "control.max.x": 1});
         } else {
             assert(!spec.hasOwnProperty("originalSpec"));
         }
     };
 
-    let userIndexes = coll.getIndexes();
-    for (const index of userIndexes) {
-        checkIndexSpec(index, /*userIndex=*/true);
-    }
+    const verifyAndDropIndex = function(isDowngradeCompatible) {
+        let userIndexes = coll.getIndexes();
+        for (const index of userIndexes) {
+            checkIndexSpec(index, /*userIndex=*/true, isDowngradeCompatible);
+        }
+
+        let bucketIndexes = bucketsColl.getIndexes();
+        for (const index of bucketIndexes) {
+            checkIndexSpec(index, /*userIndex=*/false, isDowngradeCompatible);
+        }
+
+        assert.commandWorked(coll.dropIndexes("*"));
+    };
+
+    assert.commandWorked(coll.createIndex({[timeFieldName]: 1}));
+    verifyAndDropIndex(/*isDowngradeCompatible=*/true);
+
+    assert.commandWorked(coll.createIndex({[metaFieldName]: 1}));
+    verifyAndDropIndex(/*isDowngradeCompatible=*/true);
+
+    assert.commandWorked(coll.createIndex({[timeFieldName]: 1, [metaFieldName]: 1}));
+    verifyAndDropIndex(/*isDowngradeCompatible=*/true);
+
+    if (TimeseriesTest.timeseriesMetricIndexesEnabled(db.getMongo())) {
+        assert.commandWorked(coll.createIndex({x: 1}));
+        verifyAndDropIndex(/*isDowngradeCompatible=*/false);
+
+        assert.commandWorked(
+            coll.createIndex({x: 1}, {partialFilterExpression: {x: {$type: "number"}}}));
+        verifyAndDropIndex(/*isDowngradeCompatible=*/false);
+
+        assert.commandWorked(coll.createIndex({[timeFieldName]: 1},
+                                              {partialFilterExpression: {x: {$type: "number"}}}));
+        verifyAndDropIndex(/*isDowngradeCompatible=*/false);
+
+        assert.commandWorked(coll.createIndex({[metaFieldName]: 1},
+                                              {partialFilterExpression: {x: {$type: "number"}}}));
+        verifyAndDropIndex(/*isDowngradeCompatible=*/false);
 
-    let bucketIndexes = bucketsColl.getIndexes();
-    for (const index of bucketIndexes) {
-        checkIndexSpec(index, /*userIndex=*/false);
+        assert.commandWorked(coll.createIndex({[metaFieldName]: 1, x: 1},
+                                              {partialFilterExpression: {x: {$type: "number"}}}));
+        verifyAndDropIndex(/*isDowngradeCompatible=*/false);
     }
 
     // Creating an index directly on the buckets collection is permitted. However, these types of
@@ -82,7 +102,7 @@ TimeseriesTest.run(() => {
             bucketsColl.createIndex({"control.min.y": 1, "control.max.y": 1}, {name: "y"}));
 
         let foundIndex = false;
-        bucketIndexes = bucketsColl.getIndexes();
+        let bucketIndexes = bucketsColl.getIndexes();
         for (const index of bucketIndexes) {
             if (index.name == "y") {
                 foundIndex = true;
@@ -94,7 +114,7 @@ TimeseriesTest.run(() => {
 
         // Verify that the bucket index can map to a user index.
         foundIndex = false;
-        userIndexes = coll.getIndexes();
+        let userIndexes = coll.getIndexes();
         for (const index of userIndexes) {
             if (index.name == "y") {
                 foundIndex = true;
diff --git a/jstests/noPassthrough/timeseries_measurement_indexes_downgrade.js b/jstests/noPassthrough/timeseries_measurement_indexes_downgrade.js
index 9a8593550d2..d1b913832a2 100644
--- a/jstests/noPassthrough/timeseries_measurement_indexes_downgrade.js
+++ b/jstests/noPassthrough/timeseries_measurement_indexes_downgrade.js
@@ -114,5 +114,36 @@ checkIndexForDowngrade(lastLTSFCV, true, false);
 assert.commandWorked(coll.createIndex({[metaFieldName]: "2dsphere"}));
 checkIndexForDowngrade(lastContinuousFCV, true, false);
 
+// Partial indexes are not supported in versions earlier than v5.2.
+assert.commandWorked(
+    coll.createIndex({[timeFieldName]: 1}, {partialFilterExpression: {x: {$type: "number"}}}));
+checkIndexForDowngrade(lastLTSFCV, false, false);
+
+assert.commandWorked(
+    coll.createIndex({[timeFieldName]: 1}, {partialFilterExpression: {x: {$type: "number"}}}));
+checkIndexForDowngrade(lastContinuousFCV, false, false);
+
+assert.commandWorked(
+    coll.createIndex({[metaFieldName]: 1}, {partialFilterExpression: {x: {$type: "number"}}}));
+checkIndexForDowngrade(lastLTSFCV, false, false);
+
+assert.commandWorked(
+    coll.createIndex({[metaFieldName]: 1}, {partialFilterExpression: {x: {$type: "number"}}}));
+checkIndexForDowngrade(lastContinuousFCV, false, false);
+
+assert.commandWorked(coll.createIndex({x: 1}, {partialFilterExpression: {x: {$type: "number"}}}));
+checkIndexForDowngrade(lastLTSFCV, false, false);
+
+assert.commandWorked(coll.createIndex({x: 1}, {partialFilterExpression: {x: {$type: "number"}}}));
+checkIndexForDowngrade(lastContinuousFCV, false, false);
+
+assert.commandWorked(coll.createIndex({[metaFieldName]: 1, x: 1},
+                                      {partialFilterExpression: {x: {$type: "number"}}}));
+checkIndexForDowngrade(lastLTSFCV, false, false);
+
+assert.commandWorked(coll.createIndex({x: 1, [metaFieldName]: 1},
+                                      {partialFilterExpression: {x: {$type: "number"}}}));
+checkIndexForDowngrade(lastContinuousFCV, false, false);
+
 MongoRunner.stopMongod(conn);
 }());
diff --git a/src/mongo/db/timeseries/timeseries_commands_conversion_helper.cpp b/src/mongo/db/timeseries/timeseries_commands_conversion_helper.cpp
index db4e0295c61..e857ab8a3a8 100644
--- a/src/mongo/db/timeseries/timeseries_commands_conversion_helper.cpp
+++ b/src/mongo/db/timeseries/timeseries_commands_conversion_helper.cpp
@@ -78,11 +78,17 @@ CreateIndexesCommand makeTimeseriesCreateIndexesCommand(OperationContext* opCtx,
     std::vector<mongo::BSONObj> indexes;
     for (const auto& origIndex : origIndexes) {
         BSONObjBuilder builder;
-        bool isBucketsIndexSpecCompatibleForDowngrade = false;
+        bool isBucketsIndexSpecCompatibleForDowngrade = true;
         for (const auto& elem : origIndex) {
             if (elem.fieldNameStringData() == IndexDescriptor::kPartialFilterExprFieldName) {
-                uasserted(ErrorCodes::InvalidOptions,
-                          "Partial indexes are not supported on time-series collections");
+                if (feature_flags::gTimeseriesMetricIndexes.isEnabledAndIgnoreFCV() &&
+                    serverGlobalParams.featureCompatibility.isFCVUpgradingToOrAlreadyLatest()) {
+                    // Partial indexes are not supported in FCV < 5.2.
+                    isBucketsIndexSpecCompatibleForDowngrade = false;
+                } else {
+                    uasserted(ErrorCodes::InvalidOptions,
+                              "Partial indexes are not supported on time-series collections");
+                }
             }
 
             if (elem.fieldNameStringData() == IndexDescriptor::kSparseFieldName) {
@@ -132,10 +138,12 @@ CreateIndexesCommand makeTimeseriesCreateIndexesCommand(OperationContext* opCtx,
                                       << " Command request: " << redact(origCmd.toBSON({})),
                         bucketsIndexSpecWithStatus.isOK());
 
-                isBucketsIndexSpecCompatibleForDowngrade =
-                    timeseries::isBucketsIndexSpecCompatibleForDowngrade(
+                if (!timeseries::isBucketsIndexSpecCompatibleForDowngrade(
                         options,
-                        BSON(NewIndexSpec::kKeyFieldName << bucketsIndexSpecWithStatus.getValue()));
+                        BSON(NewIndexSpec::kKeyFieldName
+                             << bucketsIndexSpecWithStatus.getValue()))) {
+                    isBucketsIndexSpecCompatibleForDowngrade = false;
+                }
 
                 builder.append(NewIndexSpec::kKeyFieldName,
                                std::move(bucketsIndexSpecWithStatus.getValue()));
diff --git a/src/mongo/db/timeseries/timeseries_constants.h b/src/mongo/db/timeseries/timeseries_constants.h
index 24e69bc1837..28dfd25ce78 100644
--- a/src/mongo/db/timeseries/timeseries_constants.h
+++ b/src/mongo/db/timeseries/timeseries_constants.h
@@ -56,6 +56,7 @@ static constexpr StringData kMetaFieldName = "metaField"_sd;
 // These are hard-coded field names in index specs.
 static constexpr StringData kKeyFieldName = "key"_sd;
 static constexpr StringData kOriginalSpecFieldName = "originalSpec"_sd;
+static constexpr StringData kPartialFilterExpressionFieldName = "partialFilterExpression"_sd;
 
 static constexpr int kTimeseriesControlDefaultVersion = 1;
 static constexpr int kTimeseriesControlCompressedVersion = 2;
diff --git a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp
index 06b701a0f92..570ab781281 100644
--- a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp
+++ b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp
@@ -389,6 +389,11 @@ bool isBucketsIndexSpecCompatibleForDowngrade(const TimeseriesOptions& timeserie
         return false;
     }
 
+    if (bucketsIndex.hasField(kPartialFilterExpressionFieldName)) {
+        // Partial indexes are not supported in FCV < 5.2.
+        return false;
+    }
+
     return createTimeseriesIndexSpecFromBucketsIndexSpec(
                timeseriesOptions,
                bucketsIndex.getField(kKeyFieldName).Obj(),