Standalone deployment
=====================

Using MognoDB 5.0
-----------------

> db.createCollection("coll1")
{ "ok" : 1 }
> db.createCollection("coll1")
{
	"ok" : 0,
	"errmsg" : "Collection already exists. NS: mydb.coll1",
	"code" : 48,
	"codeName" : "NamespaceExists"
}

> db.coll1.insert({ "name": "Antonio" })
WriteResult({ "nInserted" : 1 })
> db.createCollection("coll1")
{
	"ok" : 0,
	"errmsg" : "Collection already exists. NS: mydb.coll1",
	"code" : 48,
	"codeName" : "NamespaceExists"
}

> db.coll1.createIndex({ "idx": 1 } )
{
	"numIndexesBefore" : 1,
	"numIndexesAfter" : 2,
	"createdCollectionAutomatically" : false,
	"ok" : 1
}
> db.coll1.createIndex({ "idx": 1 } )
{
	"numIndexesBefore" : 2,
	"numIndexesAfter" : 2,
	"note" : "all indexes already exist",
	"ok" : 1
}

Summary:
* Creating a collection of which an empty collection already exists: { "ok" : 0, "errmsg" : "Collection already exists. NS: mydb.coll1", ... }
* Creating a collection of which a non empty collection exists:      { "ok" : 0, "errmsg" : "Collection already exists. NS: mydb.coll1", ... }
* Creating an index that already exists:                             { "ok" : 1, "note" : "all indexes already exist", ... }


Using MognoDB 3.6.23
--------------------

> db.createCollection("coll1")
{ "ok" : 1 }
> db.createCollection("coll1")
{
	"ok" : 0,
	"errmsg" : "a collection 'mydb.coll1' already exists",
	"code" : 48,
	"codeName" : "NamespaceExists"
}

> db.coll1.insert({ "name": "Antonio" })
WriteResult({ "nInserted" : 1 })
> db.createCollection("coll1")
{
	"ok" : 0,
	"errmsg" : "a collection 'mydb.coll1' already exists",
	"code" : 48,
	"codeName" : "NamespaceExists"
}

> db.coll1.createIndex({ "idx": 1 } )
{
	"createdCollectionAutomatically" : false,
	"numIndexesBefore" : 1,
	"numIndexesAfter" : 2,
	"ok" : 1
}
> db.coll1.createIndex({ "idx": 1 } )
{
	"numIndexesBefore" : 2,
	"numIndexesAfter" : 2,
	"note" : "all indexes already exist",
	"ok" : 1
}


Summary:
* MongoDB 5.0 and 3.6 have the same behavior


Personal conderations
---------------------

* When an entity already exist, mongod should return ok: 1 with a note, not an error (as for index creation)