diff --git a/target_bigquery/__init__.py b/target_bigquery/__init__.py
index ab3c1d5..7337f04 100644
--- a/target_bigquery/__init__.py
+++ b/target_bigquery/__init__.py
@@ -6,16 +6,14 @@
 import io
 import json
 import logging
-import os
 import sys
 
-from tempfile import mkstemp
 from joblib import Parallel, delayed, parallel_backend
 from jsonschema import Draft7Validator, FormatChecker
 from singer import get_logger
 
 from target_bigquery import stream_utils
-from target_bigquery.db_sync import DbSync
+from target_bigquery.db_sync import DbSync, flatten_record
 from target_bigquery.exceptions import (
     RecordValidationException,
     InvalidValidationOperationException
@@ -120,7 +118,19 @@ def persist_lines(config, lines) -> None:
                             "or more) Try removing 'multipleOf' methods from JSON schema.")
                     raise RecordValidationException(f"Record does not pass schema validation. RECORD: {o['record']}")
 
-            primary_key_string = stream_to_sync[stream].record_primary_key_string(o['record'])
+            if config.get('add_metadata_columns') or hard_delete_mapping.get(stream, default_hard_delete):
+                record = stream_utils.add_metadata_values_to_record(o)
+            else:
+                record = stream_utils.remove_metadata_values_from_record(o)
+
+            # Flatten record
+            record = flatten_record(
+                record,
+                stream_to_sync[stream].stream_schema_message['schema'],
+                max_level=stream_to_sync[stream].data_flattening_max_level
+            )
+
+            primary_key_string = stream_to_sync[stream].record_primary_key_string(record)
             if not primary_key_string:
                 primary_key_string = 'RID-{}'.format(total_row_count[stream])
 
@@ -130,10 +140,7 @@ def persist_lines(config, lines) -> None:
                 total_row_count[stream] += 1
 
             # append record
-            if config.get('add_metadata_columns') or hard_delete_mapping.get(stream, default_hard_delete):
-                records_to_load[stream][primary_key_string] = stream_utils.add_metadata_values_to_record(o)
-            else:
-                records_to_load[stream][primary_key_string] = o['record']
+            records_to_load[stream][primary_key_string] = record
 
             flush = False
             if row_count[stream] >= batch_size_rows:
diff --git a/target_bigquery/db_sync.py b/target_bigquery/db_sync.py
index 4216592..d7ba7f7 100644
--- a/target_bigquery/db_sync.py
+++ b/target_bigquery/db_sync.py
@@ -211,7 +211,7 @@ def flatten_record(d, schema, parent_key=[], sep='__', level=0, max_level=0):
     items = []
     for k, v in d.items():
         safe_key = safe_column_name(k, quotes=False)
-        new_key = flatten_key(k, parent_key, sep)
+        new_key = flatten_key(safe_key, parent_key, sep)
         key_schema = schema['properties'][k]
         if isinstance(v, MutableMapping) and level < max_level and 'properties' in key_schema:
             items.extend(flatten_record(
@@ -384,9 +384,8 @@ def table_name(self, stream_name, is_temporary=False, without_schema=False):
     def record_primary_key_string(self, record):
         if len(self.stream_schema_message['key_properties']) == 0:
             return None
-        flatten = flatten_record(record, self.stream_schema_message['schema'], max_level=self.data_flattening_max_level)
         try:
-            key_props = [str(flatten[p.lower()]) for p in self.stream_schema_message['key_properties']]
+            key_props = [str(record[p.lower()]) for p in self.stream_schema_message['key_properties']]
         except Exception as exc:
             logger.info("Cannot find {} primary key(s) in record: {}".format(self.stream_schema_message['key_properties'], flatten))
             raise exc
@@ -394,9 +393,7 @@ def record_primary_key_string(self, record):
 
     def records_to_json(self, records, schema):
         field_map = {field.name: field for field in schema}
-        singer_schema = self.stream_schema_message['schema']
-        flattened = (flatten_record(record, singer_schema, max_level=self.data_flattening_max_level) for record in records)
-        for record in flattened:
+        for record in records:
             yield json.dumps(
                 record,
                 cls=BigQueryJSONEncoder,
diff --git a/target_bigquery/stream_utils.py b/target_bigquery/stream_utils.py
index d5b9c7d..b31e3bd 100644
--- a/target_bigquery/stream_utils.py
+++ b/target_bigquery/stream_utils.py
@@ -86,7 +86,12 @@ def float_to_decimal(value):
         return {k: float_to_decimal(v) for k, v in value.items()}
     return value
 
-def parse_datetime(dt):
+
+def add_metadata_values_to_record(record_message):
+    """Populate metadata _sdc columns from incoming record message
+    The location of the required attributes are fixed in the stream
+    """
+    def parse_datetime(dt):
         try:
             # TODO: figure out why we can get _sdc_deleted_at as both datetime and string objects
             if isinstance(dt, date):
@@ -99,11 +104,6 @@ def parse_datetime(dt):
         except TypeError:
             return None
 
-
-def add_metadata_values_to_record(record_message):
-    """Populate metadata _sdc columns from incoming record message
-    The location of the required attributes are fixed in the stream
-    """
     extended_record = record_message['record']
     extended_record['_sdc_extracted_at'] = parse_datetime(record_message['time_extracted'])
     extended_record['_sdc_batched_at'] = datetime.now()