SERVER-25948 dbStats should indicate number of views

4 files changed, 100 insertions, 5 deletions

diff --git a/jstests/core/dbstats.js b/jstests/core/dbstats.js
new file mode 100644
index 00000000000..1547f06fd8a
--- /dev/null
+++ b/jstests/core/dbstats.js
@@ -0,0 +1,91 @@
+// Confirms that the dbStats command returns expected content.
+
+(function() {
+    "use strict";
+
+    function serverIsMongos() {
+        const res = db.runCommand("ismaster");
+        assert.commandWorked(res);
+        return res.msg === "isdbgrid";
+    }
+
+    const isMongoS = serverIsMongos();
+    const isMMAPv1 = jsTest.options().storageEngine === "mmapv1";
+
+    let testDB = db.getSiblingDB("dbstats_js");
+    assert.commandWorked(testDB.dropDatabase());
+
+    let coll = testDB["testColl"];
+    assert.commandWorked(coll.createIndex({x: 1}));
+    const doc = {_id: 1, x: 1};
+    assert.writeOK(coll.insert(doc));
+
+    let dbStats = testDB.runCommand({dbStats: 1});
+    assert.commandWorked(dbStats);
+
+    if (isMMAPv1) {
+        if (isMongoS) {
+            // When this test is run against mongoS with the mmapV1 storage engine the 'objects' and
+            // 'indexes' counts will vary depending on whether 'testColl' is sharded and on the # of
+            // shards (due to inclusion of system.indexes & system.namespaces counts).
+            assert(dbStats.hasOwnProperty("objects"), tojson(dbStats));
+            assert(dbStats.hasOwnProperty("indexes"), tojson(dbStats));
+        } else {
+            assert.eq(7,
+                      dbStats.objects,
+                      tojson(dbStats));  // Includes testColl, system.indexes & system.namespaces
+            assert.eq(2, dbStats.indexes, tojson(dbStats));
+        }
+        // 'dataSize' and 'avgObjSize' include document padding space under MMAPv1.
+        assert(dbStats.hasOwnProperty("dataSize"), tojson(dbStats));
+        assert(dbStats.hasOwnProperty("avgObjSize"), tojson(dbStats));
+    } else {
+        assert.eq(1, dbStats.objects, tojson(dbStats));  // Includes testColl only
+        const dataSize = Object.bsonsize(doc);
+        assert.eq(dataSize, dbStats.avgObjSize, tojson(dbStats));
+        assert.eq(dataSize, dbStats.dataSize, tojson(dbStats));
+
+        // Index count will vary on mongoS if an additional index is needed to support sharding.
+        if (isMongoS) {
+            assert(dbStats.hasOwnProperty("indexes"), tojson(dbStats));
+        } else {
+            assert.eq(2, dbStats.indexes, tojson(dbStats));
+        }
+    }
+
+    assert(dbStats.hasOwnProperty("storageSize"), tojson(dbStats));
+    assert(dbStats.hasOwnProperty("numExtents"), tojson(dbStats));
+    assert(dbStats.hasOwnProperty("indexSize"), tojson(dbStats));
+
+    // Confirm extentFreeList field existence. Displayed for mongoD running MMAPv1 and for mongoS
+    // regardless of storage engine.
+    if (isMMAPv1 || isMongoS) {
+        assert(dbStats.hasOwnProperty("extentFreeList"), tojson(dbStats));
+        assert(dbStats.extentFreeList.hasOwnProperty("num"), tojson(dbStats));
+        assert(dbStats.extentFreeList.hasOwnProperty("totalSize"), tojson(dbStats));
+    }
+
+    // Confirm collection and view counts on mongoD
+    if (!isMongoS) {
+        assert.eq(testDB.getName(), dbStats.db, tojson(dbStats));
+
+        // We wait to add a view until this point as it allows more exact testing of avgObjSize for
+        // WiredTiger above. Having more than 1 document would require floating point comparison.
+        assert.commandWorked(testDB.createView("testView", "testColl", []));
+
+        dbStats = testDB.runCommand({dbStats: 1});
+        assert.commandWorked(dbStats);
+
+        if (isMMAPv1) {
+            assert.eq(
+                4,
+                dbStats.collections,
+                tojson(dbStats));  // testColl + system.views + system.indexes + system.namespaces
+        } else {
+            assert.eq(2, dbStats.collections, tojson(dbStats));  // testColl + system.views
+        }
+
+        assert.eq(1, dbStats.views, tojson(dbStats));
+    }
+
+})();
diff --git a/src/mongo/db/catalog/database.cpp b/src/mongo/db/catalog/database.cpp
index 005a4f23abf..85d3eab7f34 100644
--- a/src/mongo/db/catalog/database.cpp
+++ b/src/mongo/db/catalog/database.cpp
@@ -322,7 +322,8 @@ void Database::getStats(OperationContext* opCtx, BSONObjBuilder* output, double
     list<string> collections;
     _dbEntry->getCollectionNamespaces(&collections);
 
-    long long ncollections = 0;
+    long long nCollections = 0;
+    long long nViews = 0;
     long long objects = 0;
     long long size = 0;
     long long storageSize = 0;
@@ -337,7 +338,7 @@ void Database::getStats(OperationContext* opCtx, BSONObjBuilder* output, double
         if (!collection)
             continue;
 
-        ncollections += 1;
+        nCollections += 1;
         objects += collection->numRecords(opCtx);
         size += collection->dataSize(opCtx);
 
@@ -349,7 +350,10 @@ void Database::getStats(OperationContext* opCtx, BSONObjBuilder* output, double
         indexSize += collection->getIndexSize(opCtx);
     }
 
-    output->appendNumber("collections", ncollections);
+    getViewCatalog()->iterate(opCtx, [&](const ViewDefinition& view) { nViews += 1; });
+
+    output->appendNumber("collections", nCollections);
+    output->appendNumber("views", nViews);
     output->appendNumber("objects", objects);
     output->append("avgObjSize", objects == 0 ? 0 : double(size) / double(objects));
     output->appendNumber("dataSize", size / scale);
diff --git a/src/mongo/db/commands/dbcommands.cpp b/src/mongo/db/commands/dbcommands.cpp
index 9720775b0cf..f73166e42fa 100644
--- a/src/mongo/db/commands/dbcommands.cpp
+++ b/src/mongo/db/commands/dbcommands.cpp
@@ -1038,6 +1038,7 @@ public:
             // is not needed for the missing DB case, we can just do the same that's done in
             // CollectionStats.
             result.appendNumber("collections", 0);
+            result.appendNumber("views", 0);
             result.appendNumber("objects", 0);
             result.append("avgObjSize", 0);
             result.appendNumber("dataSize", 0);
diff --git a/src/mongo/s/commands/cluster_db_stats_cmd.cpp b/src/mongo/s/commands/cluster_db_stats_cmd.cpp
index 4661cac2b7b..1546fe4482e 100644
--- a/src/mongo/s/commands/cluster_db_stats_cmd.cpp
+++ b/src/mongo/s/commands/cluster_db_stats_cmd.cpp
@@ -83,8 +83,7 @@ public:
             }
         }
 
-        // TODO: need to find a good way to get this
-        // result.appendNumber( "collections" , ncollections );
+        // TODO SERVER-26110: Add aggregated 'collections' and 'views' metrics.
         output.appendNumber("objects", objects);
 
         // avgObjSize on mongod is not scaled based on the argument to db.stats(), so we use