SERVER-12088 Enable usePowerOf2Sizes as server-wide default

19 files changed, 126 insertions, 63 deletions

diff --git a/jstests/auth/user_management_commands.js b/jstests/auth/user_management_commands.js
index 931feae7e69..5f94f4aa217 100644
--- a/jstests/auth/user_management_commands.js
+++ b/jstests/auth/user_management_commands.js
@@ -145,6 +145,7 @@ function runTest(conn) {
          jsTestLog("Testing usersInfo");
 
          var res = testUserAdmin.runCommand({usersInfo: 'spencer'});
+         printjson(res);
          assert.eq(1, res.users.length);
          assert.eq(10036, res.users[0].customData.zipCode);
 
@@ -153,9 +154,19 @@ function runTest(conn) {
          assert.eq(10036, res.users[0].customData.zipCode);
 
          res = testUserAdmin.runCommand({usersInfo: ['spencer', {user: 'userAdmin', db: 'admin'}]});
+         printjson(res);
          assert.eq(2, res.users.length);
-         assert.eq(10036, res.users[0].customData.zipCode);
-         assert(res.users[1].customData.userAdmin);
+         if (res.users[0].user == "spencer") {
+             assert.eq(10036, res.users[0].customData.zipCode);
+             assert(res.users[1].customData.userAdmin);
+         } else if (res.users[0].user == "userAdmin") {
+             assert.eq(10036, res.users[1].customData.zipCode);
+             assert(res.users[0].customData.userAdmin);
+         } else {
+             doassert("Expected user names returned by usersInfo to be either 'userAdmin' or 'spencer', "
+                      + "but got: " + res.users[0].user);
+         }
+
 
          res = testUserAdmin.runCommand({usersInfo: 1});
          assert.eq(2, res.users.length);
@@ -177,6 +188,7 @@ function runTest(conn) {
 
 jsTest.log('Test standalone');
 var conn = MongoRunner.runMongod({ auth: '' });
+conn.getDB('admin').runCommand({setParameter:1, newCollectionsUsePowerOf2Sizes: false});
 runTest(conn);
 MongoRunner.stopMongod(conn.port);
 
diff --git a/jstests/collmod.js b/jstests/collmod.js
index 198c4bf8c02..2dc5555f3ec 100644
--- a/jstests/collmod.js
+++ b/jstests/collmod.js
@@ -12,17 +12,18 @@ t.drop();
 db.createCollection( coll );
 
 
-// Verify the new collection has userFlags set to 0
-assert.eq( t.stats().userFlags , 0 , "fresh collection doesn't have userFlags = 0 ");
+// Verify the new collection has userFlags set to 1
+printjson(t.stats());
+assert.eq( t.stats().userFlags , 1 , "fresh collection doesn't have userFlags = 1 ");
 
-// Modify the collection with the usePowerOf2Sizes flag. Verify userFlags now = 1.
-var res = db.runCommand( { "collMod" : coll,  "usePowerOf2Sizes" : true } );
+// Modify the collection with the usePowerOf2Sizes flag. Verify userFlags now = 0.
+var res = db.runCommand( { "collMod" : coll,  "usePowerOf2Sizes" : false } );
 debug( res );
 assert.eq( res.ok , 1 , "collMod failed" );
-assert.eq( t.stats().userFlags , 1 , "modified collection should have userFlags = 1 ");
+assert.eq( t.stats().userFlags , 0 , "modified collection should have userFlags = 0 ");
 var nso = db.system.namespaces.findOne( { name : t.getFullName() } );
 debug( nso );
-assert.eq( 1, nso.options.flags, "options didn't sync to system.namespaces: " + tojson( nso ) );
+assert.eq( 0, nso.options.flags, "options didn't sync to system.namespaces: " + tojson( nso ) );
 
 // Try to modify it with some unrecognized value
 var res = db.runCommand( { "collMod" : coll,  "unrecognized" : true } );
@@ -71,11 +72,11 @@ assert.eq( 0, res.ok, "shouldn't be able to modify faulty index spec" );
 t.dropIndex( {a : 1 } );
 t.ensureIndex( {a : 1} , { "expireAfterSeconds": 50 } )
 var res = db.runCommand( { "collMod" : coll ,
-                           "usePowerOf2Sizes" : false,
+                           "usePowerOf2Sizes" : true,
                            "index" : { "keyPattern" : {a : 1} , "expireAfterSeconds" : 100 } } );
 debug( res );
 assert.eq( 1, res.ok, "should be able to modify both userFlags and expireAfterSeconds" );
-assert.eq( t.stats().userFlags , 0 , "userflags should be 0 now");
+assert.eq( t.stats().userFlags , 1 , "userflags should be 1 now");
 assert.eq( 1, db.system.indexes.count( { key : {a:1}, expireAfterSeconds : 100 } ),
            "TTL index should be 100 now" );
 
diff --git a/jstests/compactPreservePadding.js b/jstests/compactPreservePadding.js
index dd0c6ddf8cb..5a4ac949f49 100644
--- a/jstests/compactPreservePadding.js
+++ b/jstests/compactPreservePadding.js
@@ -1,24 +1,24 @@
 // test preservePadding
-collName = "compactPreservePadding";
-mydb = db.getSisterDB("compactPreservePaddingDB");
-mydb.dropDatabase();
-mydb.createCollection(collName);
-// ensure there is some padding by using power of 2 sizes
-mydb.runCommand({collMod: collName, usePowerOf2Sizes: true});
-t = mydb.compactPreservePadding;
+
+var collName = "compactPreservePadding";
+var t = db.getCollection(collName);
 t.drop();
-// populate db
+
+// use larger keyname to avoid hitting an edge case with extents 
 for (i = 0; i < 10000; i++) {
-    t.insert({x:i});
+    t.insert({useLargerKeyName:i});
 }
+
 // remove half the entries
-t.remove({x:{$mod:[2,0]}})
+t.remove({useLargerKeyName:{$mod:[2,0]}})
 printjson(t.stats());
 originalSize = t.stats().size;
 originalStorage = t.stats().storageSize;
+
 // compact!
-mydb.runCommand({compact: collName, preservePadding: true});
+db.runCommand({compact: collName, preservePadding: true});
 printjson(t.stats());
+
 // object sizes ('size') should be the same (unless we hit an edge case involving extents, which
 // this test doesn't) and storage size should shrink
 assert(originalSize == t.stats().size);
diff --git a/jstests/datasize.js b/jstests/datasize.js
index 277efac4bdf..13e9f11bf0c 100644
--- a/jstests/datasize.js
+++ b/jstests/datasize.js
@@ -1,6 +1,11 @@
+// test end-to-end data allocation without powerOf2Sizes enabled
 f = db.jstests_datasize;
 f.drop();
 
+// this test requires usePowerOf2Sizes to be off
+db.createCollection( f.getName(), { usePowerOf2Sizes: false } );
+assert.eq(0, f.stats().userFlags);
+
 assert.eq( 0, db.runCommand( {datasize:"test.jstests_datasize"} ).size );
 f.save( {qq:'c'} );
 assert.eq( 32, db.runCommand( {datasize:"test.jstests_datasize"} ).size );
@@ -8,6 +13,8 @@ f.save( {qq:'fg'} );
 assert.eq( 68, db.runCommand( {datasize:"test.jstests_datasize"} ).size );
 
 f.drop();
+db.createCollection( f.getName(), { usePowerOf2Sizes: false} );
+
 f.ensureIndex( {qq:1} );
 assert.eq( 0, db.runCommand( {datasize:"test.jstests_datasize"} ).size );
 f.save( {qq:'c'} );
diff --git a/jstests/fts1.js b/jstests/fts1.js
index 6af3f133694..6bd138d6c25 100644
--- a/jstests/fts1.js
+++ b/jstests/fts1.js
@@ -1,9 +1,12 @@
-
 load( "jstests/libs/fts.js" );
 
 t = db.text1;
 t.drop();
 
+// this test requires usePowerOf2Sizes to be off
+db.createCollection( t.getName(), {"usePowerOf2Sizes" : false } );
+assert.eq(0, t.stats().userFlags);
+
 assert.eq( [] , queryIDS( t , "az" ) , "A0" );
 
 t.save( { _id : 1 , x : "az b c" } );
@@ -24,4 +27,3 @@ assert.eq( [4] , queryIDS( t , "d" ) , "A2" );
 idx = db.system.indexes.findOne( { ns: t.getFullName(), "weights.x" : 1 } )
 assert( idx.v >= 1, tojson( idx ) )
 assert( idx.textIndexVersion >= 1, tojson( idx ) )
-
diff --git a/jstests/padding.js b/jstests/padding.js
index af68e7212ed..1872574d80f 100644
--- a/jstests/padding.js
+++ b/jstests/padding.js
@@ -1,6 +1,10 @@
 p = db.getCollection("padding");
 p.drop();
 
+// this test requires usePowerOf2Sizes to be off 
+db.createCollection( p.getName(), { "usePowerOf2Sizes" : false } );
+assert.eq(0, p.stats().userFlags);
+
 for (var i = 0; i < 1000; i++) {
     p.insert({ x: 1, y: "aaaaaaaaaaaaaaa" });
 }
diff --git a/jstests/profile3.js b/jstests/profile3.js
index a7072be235c..6091cdafdb3 100644
--- a/jstests/profile3.js
+++ b/jstests/profile3.js
@@ -26,6 +26,7 @@ try {
     
     db.setProfilingLevel(2);
     
+    db.createCollection(t.getName(), {usePowerOf2Sizes: false});
     t.insert( { x : 1 } );
     t.findOne( { x : 1 } );
     t.find( { x : 1 } ).count();
diff --git a/jstests/sharding/authCommands.js b/jstests/sharding/authCommands.js
index 80c18400f46..93d178222f5 100644
--- a/jstests/sharding/authCommands.js
+++ b/jstests/sharding/authCommands.js
@@ -4,7 +4,7 @@
 var doTest = function() {
 
 var rsOpts = { oplogSize: 10, verbose : 2, useHostname : false };
-var st = new ShardingTest({ keyFile : 'jstests/libs/key1', shards : 2, chunksize : 1, config : 3,
+var st = new ShardingTest({ keyFile : 'jstests/libs/key1', shards : 2, chunksize : 2, config : 3,
                             rs : rsOpts, other : { nopreallocj : 1, verbose : 2, useHostname : false }});
 
 var mongos = st.s;
diff --git a/jstests/sharding/localhostAuthBypass.js b/jstests/sharding/localhostAuthBypass.js
index 82d8b43a474..28f3a963239 100644
--- a/jstests/sharding/localhostAuthBypass.js
+++ b/jstests/sharding/localhostAuthBypass.js
@@ -126,7 +126,7 @@ var setupSharding = function(mongo) {
     mongo.getDB("admin").runCommand({shardCollection : "test.foo", key : {_id : 1}});
 
     var test = mongo.getDB("test");
-    for(i = 1; i < 40; i++) {
+    for(i = 1; i < 20; i++) {
         test.foo.insert({_id: i});
     }
 };
@@ -228,4 +228,4 @@ var runTest = function(useHostName) {
 }
 
 runTest(false);
-runTest(true);
\ No newline at end of file
+runTest(true);
diff --git a/jstests/sharding/migrateBig.js b/jstests/sharding/migrateBig.js
index 853a671915a..2c4d156d760 100644
--- a/jstests/sharding/migrateBig.js
+++ b/jstests/sharding/migrateBig.js
@@ -15,7 +15,9 @@ for ( x=0; x<100; x++ )
     coll.insert( { x : x , big : big } )
 db.getLastError();
 
-s.adminCommand( { split : "test.foo" , middle : { x : 33 } } )
+db.printShardingStatus()
+
+s.adminCommand( { split : "test.foo" , middle : { x : 30 } } )
 s.adminCommand( { split : "test.foo" , middle : { x : 66 } } )
 s.adminCommand( { movechunk : "test.foo" , find : { x : 90 } , to : s.getOther( s.getServer( "test" ) ).name } )
 
diff --git a/jstests/sharding/shard_existing.js b/jstests/sharding/shard_existing.js
index 51bd43f470a..b16c1796cd9 100644
--- a/jstests/sharding/shard_existing.js
+++ b/jstests/sharding/shard_existing.js
@@ -1,4 +1,3 @@
-
 s = new ShardingTest( "shard_existing" , 2 /* numShards */, 1 /* verboseLevel */, 1 /* numMongos */, { chunksize : 1 } )
 
 db = s.getDB( "test" )
@@ -6,12 +5,16 @@ db = s.getDB( "test" )
 var stringSize = 10000;
 var numDocs = 2000;
 
+
 // we want a lot of data, so lets make a string to cheat :)
 var bigString = new Array(stringSize).toString();
 var docSize = Object.bsonsize({ _id: numDocs, s: bigString });
 var totalSize = docSize * numDocs;
 print("NumDocs: " + numDocs + " DocSize: " + docSize + " TotalSize: " + totalSize);
 
+// turn off powerOf2Sizes as this tests regular allocation
+db.createCollection('data', {usePowerOf2Sizes: false});
+
 for (i=0; i<numDocs; i++) {
     db.data.insert({_id: i, s: bigString});
 }
diff --git a/jstests/sharding/user_flags_sharded.js b/jstests/sharding/user_flags_sharded.js
index e67a062f71f..6378b53e85d 100644
--- a/jstests/sharding/user_flags_sharded.js
+++ b/jstests/sharding/user_flags_sharded.js
@@ -18,10 +18,10 @@ db1.createCollection( coll );
 var collstats = db1.getCollection( coll ).stats()
 print( "*************** Fresh Collection Stats ************" );
 printjson( collstats );
-assert.eq( collstats.userFlags , 0 , "fresh collection doesn't have userFlags = 0 ");
+assert.eq( collstats.userFlags , 1 , "fresh collection doesn't have userFlags = 1 ");
 
 // Now we modify the collection with the usePowerOf2Sizes flag
-var res = db1.runCommand( { "collMod" : coll ,  "usePowerOf2Sizes" : true } );
+var res = db1.runCommand( { "collMod" : coll ,  "usePowerOf2Sizes" : false } );
 assert.eq( res.ok , 1 , "collMod failed" );
 
 // and insert some stuff, for the hell of it
@@ -29,11 +29,11 @@ var numdocs = 20;
 for( i=0; i < numdocs; i++){ db1.getCollection( coll ).insert( {_id : i} ); }
 db1.getLastError()
 
-// Next verify that userFlags has changed to 1
+// Next verify that userFlags has changed to 0
 collstats = db1.getCollection( coll ).stats()
 print( "*************** Collection Stats After CollMod ************" );
 printjson( collstats );
-assert.eq( collstats.userFlags , 1 , "modified collection should have userFlags = 1 ");
+assert.eq( collstats.userFlags , 0 , "modified collection should have userFlags = 0 ");
 
 // start up a new sharded cluster, and add previous mongod
 var s = new ShardingTest( "user_flags", 1 );
@@ -53,7 +53,7 @@ shard2stats = shard2.getCollection( coll ).stats()
 printjson( shard2stats );
 
 assert.eq( shard2stats.count , numdocs , "moveChunk didn't succeed" );
-assert.eq( shard2stats.userFlags , 1 , "new shard should also have userFlags = 1 ");
+assert.eq( shard2stats.userFlags , 0 , "new shard should also have userFlags = 0 ");
 
 stopMongod( 29000 );
 s.stop();
diff --git a/jstests/slowNightly/ttl_repl.js b/jstests/slowNightly/ttl_repl.js
index 1f41d3d36ea..3b251dfa8a9 100644
--- a/jstests/slowNightly/ttl_repl.js
+++ b/jstests/slowNightly/ttl_repl.js
@@ -23,8 +23,11 @@ var slave1db = slave1.getDB( 'd' );
 var mastercol = masterdb[ 'c' ];
 var slave1col = slave1db[ 'c' ];
 
-// create new collection. insert 24 docs, aged at one-hour intervalss
+// turn off usePowerOf2Sizes as this tests the flag is set automatically
 mastercol.drop();
+masterdb.createCollection(mastercol.getName(), {usePowerOf2Sizes: false});
+
+// create new collection. insert 24 docs, aged at one-hour intervalss
 now = (new Date()).getTime();
 for ( i=0; i<24; i++ )
     mastercol.insert( { x : new Date( now - ( 3600 * 1000 * i ) ) } );
diff --git a/jstests/splitvector.js b/jstests/splitvector.js
index b8f293582a7..d239625de67 100644
--- a/jstests/splitvector.js
+++ b/jstests/splitvector.js
@@ -45,12 +45,17 @@ var assertFieldNamesMatch = function( splitPoint , keyPattern ){
     }
 }
 
+// turn off powerOf2, this test checks regular allocation 
+var resetCollection = function() {
+    f.drop();
+    db.createCollection(f.getName(), {usePowerOf2Sizes: false});
+}
+
 // -------------------------
 //  TESTS START HERE
 // -------------------------
-
 f = db.jstests_splitvector;
-f.drop();
+resetCollection();
 
 // -------------------------
 // Case 1: missing parameters 
@@ -75,7 +80,7 @@ assert.eq( [], db.runCommand( { splitVector: "test.jstests_splitvector" , keyPat
 // -------------------------
 // Case 4: uniform collection
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1 } );
 
 var case4 = function() {
@@ -109,7 +114,7 @@ case4();
 // -------------------------
 // Case 5: limit number of split points
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1 } );
 
 var case5 = function() {
@@ -132,7 +137,7 @@ case5();
 // -------------------------
 // Case 6: limit number of objects in a chunk
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1 } );
 
 var case6 = function() {
@@ -156,7 +161,7 @@ case6();
 // Case 7: enough occurances of min key documents to pass the chunk limit
 // [1111111111111111,2,3)
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1 } );
 
 var case7 = function() {
@@ -184,7 +189,7 @@ case7();
 // Case 8: few occurrances of min key, and enough of some other that we cannot split it
 // [1, 22222222222222, 3)
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1 } );
 
 var case8 = function() {
@@ -218,7 +223,7 @@ case8();
 // Case 9: splitVector "force" mode, where we split (possible small) chunks in the middle
 //
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1 } );
 
 var case9 = function() {
@@ -253,51 +258,51 @@ case9();
 // Repeat all cases using prefix shard key.
 //
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: 1 } );
 case4();
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: -1 , z : 1 } );
 case4();
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: 1 } );
 case5();
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: -1 , z : 1 } );
 case5();
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: 1 } );
 case6();
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: -1 , z : 1 } );
 case6();
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: 1 } );
 case7();
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: -1 , z : 1 } );
 case7();
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: 1 } );
 case8();
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: -1 , z : 1 } );
 case8();
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: 1 } );
 case9();
 
-f.drop();
+resetCollection();
 f.ensureIndex( { x: 1, y: -1 , z : 1 } );
 case9();
 
diff --git a/jstests/tool/dumprestore_auth.js b/jstests/tool/dumprestore_auth.js
index 9349681129e..55f18b018db 100644
--- a/jstests/tool/dumprestore_auth.js
+++ b/jstests/tool/dumprestore_auth.js
@@ -13,8 +13,9 @@ adminDB.createUser({user: 'restore', pwd: 'password', roles: ['restore']});
 assert.eq(0 , c.count() , "setup1");
 c.save({ a : 22 });
 assert.eq(1 , c.count() , "setup2");
-assert.commandWorked(c.runCommand("collMod", {usePowerOf2Sizes: true}));
-assert.eq(1, c.getDB().system.namespaces.findOne({name: c.getFullName()}).options.flags);
+
+assert.commandWorked(c.runCommand("collMod", {usePowerOf2Sizes: false}));
+assert.eq(0, c.getDB().system.namespaces.findOne({name: c.getFullName()}).options.flags);
 
 t.runTool("dump" , "--out" , t.ext, "--username", "backup", "--password", "password");
 
@@ -28,7 +29,7 @@ t.runTool("restore" , "--dir" , t.ext, "--username", "restore", "--password", "p
 assert.soon("c.findOne()" , "no data after sleep");
 assert.eq(1 , c.count() , "after restore 2");
 assert.eq(22 , c.findOne().a , "after restore 2");
-assert.eq(1, c.getDB().system.namespaces.findOne({name: c.getFullName()}).options.flags);
+assert.eq(0, c.getDB().system.namespaces.findOne({name: c.getFullName()}).options.flags);
 assert.eq(3, adminDB.system.users.count());
 
 t.stop();
diff --git a/src/mongo/db/catalog/database.cpp b/src/mongo/db/catalog/database.cpp
index 8c2fe0e1f2c..74c5bccbcbc 100644
--- a/src/mongo/db/catalog/database.cpp
+++ b/src/mongo/db/catalog/database.cpp
@@ -47,11 +47,14 @@
 #include "mongo/db/pdfile.h"
 #include "mongo/db/query/internal_plans.h"
 #include "mongo/db/ops/delete.h"
+#include "mongo/db/server_parameters.h"
 #include "mongo/db/storage_options.h"
 #include "mongo/db/catalog/collection.h"
 
 namespace mongo {
 
+    MONGO_EXPORT_SERVER_PARAMETER(newCollectionsUsePowerOf2Sizes, bool, true);
+
     void massertNamespaceNotIndex( const StringData& ns, const StringData& caller ) {
         massert( 17320,
                  str::stream() << "cannot do " << caller
@@ -555,6 +558,7 @@ namespace mongo {
         return c;
     }
 
+
     Collection* Database::createCollection( const StringData& ns, bool capped,
                                             const BSONObj* options, bool allocateDefaultSpace ) {
         verify( _namespaceIndex.details( ns ) == NULL );
@@ -569,6 +573,20 @@ namespace mongo {
 
         audit::logCreateCollection( currentClient.get(), ns );
 
+        // allocation strategy set explicitly in flags or by server-wide default
+        // need to check validity before creating the collection
+        int userFlags = 0;
+        bool flagSet = false;
+
+        if ( options && options->getField("flags").type() ) {
+            uassert( 17351, "flags must be a number", options->getField("flags").isNumber() );
+            userFlags = options->getField("flags").numberInt();
+            flagSet = true;
+        }
+        if ( newCollectionsUsePowerOf2Sizes && !flagSet && !capped ) {
+            userFlags = NamespaceDetails::Flag_UsePowerOf2Sizes;
+        }
+
         _namespaceIndex.add_ns( ns, DiskLoc(), capped );
         _addNamespaceToCatalog( ns, options );
 
@@ -584,6 +602,9 @@ namespace mongo {
         Collection* collection = getCollection( ns );
         verify( collection );
 
+        NamespaceDetails* nsd = collection->details();
+        nsd->setUserFlag( userFlags );
+
         if ( allocateDefaultSpace ) {
             collection->increaseStorageSize( Extent::initialSize( 128 ), false );
         }
@@ -599,6 +620,7 @@ namespace mongo {
             }
         }
 
+
         return collection;
     }
 
diff --git a/src/mongo/db/pdfile.cpp b/src/mongo/db/pdfile.cpp
index 3ab86037cc8..7b142cf64ab 100644
--- a/src/mongo/db/pdfile.cpp
+++ b/src/mongo/db/pdfile.cpp
@@ -277,10 +277,6 @@ namespace mongo {
         if ( mx > 0 )
             d->setMaxCappedDocs( mx );
 
-        if ( options["flags"].numberInt() ) {
-            d->replaceUserFlags( options["flags"].numberInt() );
-        }
-
         return true;
     }
 
diff --git a/src/mongo/dbtests/namespacetests.cpp b/src/mongo/dbtests/namespacetests.cpp
index 9aa68ba6e67..6658b5329cd 100644
--- a/src/mongo/dbtests/namespacetests.cpp
+++ b/src/mongo/dbtests/namespacetests.cpp
@@ -1358,6 +1358,7 @@ namespace NamespaceTests {
         public:
             void run() {
                 create();
+                ASSERT( nsd()->clearUserFlag( NamespaceDetails::Flag_UsePowerOf2Sizes ) );
                 ASSERT_EQUALS( 1.0, nsd()->paddingFactor() );
                 ASSERT_EQUALS( 300, nsd()->getRecordAllocationSize( 300 ) );
             }
@@ -1371,6 +1372,7 @@ namespace NamespaceTests {
                 create();
                 double paddingFactor = 1.2;
                 nsd()->setPaddingFactor( paddingFactor );
+                ASSERT( nsd()->clearUserFlag( NamespaceDetails::Flag_UsePowerOf2Sizes ) );
                 ASSERT_EQUALS( paddingFactor, nsd()->paddingFactor() );
                 ASSERT_EQUALS( static_cast<int>( 300 * paddingFactor ),
                                nsd()->getRecordAllocationSize( 300 ) );
@@ -1386,7 +1388,6 @@ namespace NamespaceTests {
         public:
             void run() {
                 create();
-                ASSERT( nsd()->setUserFlag( NamespaceDetails::Flag_UsePowerOf2Sizes ) );
                 ASSERT( nsd()->isUserFlagSet( NamespaceDetails::Flag_UsePowerOf2Sizes ) );
                 ASSERT_EQUALS( 512, nsd()->getRecordAllocationSize( 300 ) );
             }
@@ -1402,7 +1403,6 @@ namespace NamespaceTests {
         public:
             void run() {
                 create();
-                ASSERT( nsd()->setUserFlag( NamespaceDetails::Flag_UsePowerOf2Sizes ) );
                 ASSERT( nsd()->isUserFlagSet( NamespaceDetails::Flag_UsePowerOf2Sizes ) );
                 nsd()->setPaddingFactor( 2.0 );
                 ASSERT_EQUALS( 2.0, nsd()->paddingFactor() );
@@ -1429,6 +1429,7 @@ namespace NamespaceTests {
         public:
             void run() {
                 create();
+                ASSERT( !nsd()->isUserFlagSet( NamespaceDetails::Flag_UsePowerOf2Sizes ) );
                 DiskLoc loc = nsd()->alloc( ns(), 300 );
                 ASSERT_EQUALS( 300, loc.rec()->lengthWithHeaders() );
             }
diff --git a/src/mongo/shell/db.js b/src/mongo/shell/db.js
index db0c4c27386..55bf47d7891 100644
--- a/src/mongo/shell/db.js
+++ b/src/mongo/shell/db.js
@@ -80,6 +80,7 @@ DB.prototype._adminCommand = DB.prototype.adminCommand; // alias old name
         capped: if true, this is a capped collection (where old data rolls out).
     </li>
     <li> max: maximum number of objects if capped (optional).</li>
+    <li> usePowerOf2Sizes: if true, set usePowerOf2Sizes allocation for the collection.</li>
     </ul>
 
     <p>Example:</p>
@@ -100,6 +101,8 @@ DB.prototype.createCollection = function(name, opt) {
         cmd.capped = options.capped;
     if (options.size != undefined)
         cmd.size = options.size;
+    if (options.usePowerOf2Sizes != undefined) 
+        cmd.flags = options.usePowerOf2Sizes ? 1 : 0;
     var res = this._dbCommand(cmd);
     return res;
 }