diff --git a/haystack/database/elasticsearch.py b/haystack/database/elasticsearch.py
index 1ca6b0eaec..1ca0ab3cd2 100644
--- a/haystack/database/elasticsearch.py
+++ b/haystack/database/elasticsearch.py
@@ -412,7 +412,9 @@ def query_by_embedding(self,
     def _convert_es_hit_to_document(self, hit: dict, score_adjustment: int = 0) -> Document:
         # We put all additional data of the doc into meta_data and return it in the API
         meta_data = {k:v for k,v in hit["_source"].items() if k not in (self.text_field, self.faq_question_field, self.embedding_field)}
-        meta_data["name"] = meta_data.pop(self.name_field, None)
+        name = meta_data.pop(self.name_field, None)
+        if name:
+            meta_data["name"] = name
 
         document = Document(
             id=hit["_id"],
diff --git a/haystack/database/sql.py b/haystack/database/sql.py
index ff4e1e9131..d7e5a234a9 100644
--- a/haystack/database/sql.py
+++ b/haystack/database/sql.py
@@ -68,14 +68,14 @@ def __init__(self, url: str = "sqlite://", index="document"):
         self.index = index
         self.label_index = "label"
 
-    def get_document_by_id(self, id: str, index=None) -> Optional[Document]:
-        index = index or self.index
-        document_row = self.session.query(DocumentORM).filter_by(index=index, id=id).first()
-        document = document_row or self._convert_sql_row_to_document(document_row)
+    def get_document_by_id(self, id: str, index: Optional[str] = None) -> Optional[Document]:
+        documents = self.get_documents_by_id([id], index)
+        document = documents[0] if documents else None
         return document
 
-    def get_documents_by_id(self, ids: List[str]) -> List[Document]:
-        results = self.session.query(DocumentORM).filter(DocumentORM.id.in_(ids)).all()
+    def get_documents_by_id(self, ids: List[str], index: Optional[str] = None) -> List[Document]:
+        index = index or self.index
+        results = self.session.query(DocumentORM).filter(DocumentORM.id.in_(ids), DocumentORM.index == index).all()
         documents = [self._convert_sql_row_to_document(row) for row in results]
 
         return documents
@@ -138,7 +138,8 @@ def write_documents(self, documents: Union[List[dict], List[Document]], index: O
         document_objects = [Document.from_dict(d) if isinstance(d, dict) else d for d in documents]
         index = index or self.index
         for doc in document_objects:
-            meta_orms = [MetaORM(name=key, value=value) for key, value in doc.meta.items()]
+            meta_fields = doc.meta or {}
+            meta_orms = [MetaORM(name=key, value=value) for key, value in meta_fields.items()]
             doc_orm = DocumentORM(id=doc.id, text=doc.text, meta=meta_orms, index=index)
             self.session.add(doc_orm)
         self.session.commit()
diff --git a/test/test_db.py b/test/test_db.py
index 5b0a6a7ef2..230ea772df 100644
--- a/test/test_db.py
+++ b/test/test_db.py
@@ -4,6 +4,7 @@
 
 from haystack.database.base import Document, Label
 from haystack.database.elasticsearch import ElasticsearchDocumentStore
+from haystack.database.faiss import FAISSDocumentStore
 
 
 def test_get_all_documents_without_filters(document_store_with_docs):
@@ -42,6 +43,39 @@ def test_get_documents_by_id(document_store_with_docs):
     assert doc.text == documents[0].text
 
 
+def test_write_document_meta(document_store):
+    documents = [
+        {"text": "dict_without_meta", "id": "1"},
+        {"text": "dict_with_meta", "meta_field": "test2", "name": "filename2", "id": "2"},
+        Document(text="document_object_without_meta", id="3"),
+        Document(text="document_object_with_meta", meta={"meta_field": "test4", "name": "filename3"}, id="4"),
+    ]
+    document_store.write_documents(documents)
+    documents_in_store = document_store.get_all_documents()
+    assert len(documents_in_store) == 4
+
+    assert not document_store.get_document_by_id("1").meta
+    assert document_store.get_document_by_id("2").meta["meta_field"] == "test2"
+    assert not document_store.get_document_by_id("3").meta
+    assert document_store.get_document_by_id("4").meta["meta_field"] == "test4"
+
+
+def test_write_document_index(document_store):
+    documents = [
+        {"text": "text1", "id": "1"},
+        {"text": "text2", "id": "2"},
+    ]
+    document_store.write_documents([documents[0]], index="haystack_test_1")
+    assert len(document_store.get_all_documents(index="haystack_test_1")) == 1
+
+    if not isinstance(document_store, FAISSDocumentStore):  # addition of more documents is not supported in FAISS
+        document_store.write_documents([documents[1]], index="haystack_test_2")
+        assert len(document_store.get_all_documents(index="haystack_test_2")) == 1
+
+    assert len(document_store.get_all_documents(index="haystack_test_1")) == 1
+    assert len(document_store.get_all_documents()) == 0
+
+
 def test_labels(document_store):
     label = Label(
         question="question",