diff --git a/sheetsync/sheetsync/main.py b/sheetsync/sheetsync/main.py
index be9ae7d..e898872 100644
--- a/sheetsync/sheetsync/main.py
+++ b/sheetsync/sheetsync/main.py
@@ -112,15 +112,24 @@ class SheetSync(object):
 				db_rows = self.get_db_rows()
 				seen = set()
 
-				for row in self.middleware.get_rows():
+				is_full, sheet_rows = self.middleware.get_rows()
+				for row in sheet_rows:
 					if row['id'] in seen:
 						self.logger.error("Duplicate id {}, skipping".format(row['id']))
 						continue
 					seen.add(row['id'])
 					self.sync_row(row, db_rows.get(row['id']))
 
-				for db_row in [r for id, r in db_rows.items() if id not in seen]:
-					self.sync_row(None, db_row)
+				if is_full:
+					# Find rows that were not in the sheet.
+					# Only do this if we did a full sync, otherwise things might be missing
+					# simply because they're in a worksheet we didn't sync.
+					missing = [
+						r for id, r in db_rows.items()
+						if id not in seen
+					]
+					for db_row in missing:
+						self.sync_row(None, db_row)
 
 			except Exception as e:
 				# for HTTPErrors, http response body includes the more detailed error
diff --git a/sheetsync/sheetsync/sheets.py b/sheetsync/sheetsync/sheets.py
index 73cf25c..712b05d 100644
--- a/sheetsync/sheetsync/sheets.py
+++ b/sheetsync/sheetsync/sheets.py
@@ -149,7 +149,7 @@ class SheetsMiddleware():
 		for quota limit reasons."""
 		if self.sync_count % self.SYNCS_PER_INACTIVE_CHECK == 0:
 			# check all worksheets
-			worksheets = self.worksheets
+			worksheets = list(self.worksheets.keys())
 		else:
 			# only check most recently changed worksheets
 			worksheets = sorted(
@@ -160,10 +160,14 @@ class SheetsMiddleware():
 		return worksheets
 
 	def get_rows(self):
-		"""Fetch all rows of worksheet, parsed into a list of dicts."""
+		"""Fetch all rows of worksheet, parsed into a list of dicts.
+		Return (is_full, all rows).
+		"""
 		# Clear previously seen unassigned rows
 		self.unassigned_rows = {}
-		for worksheet in self.pick_worksheets():
+		worksheets = self.pick_worksheets()
+		all_rows = []
+		for worksheet in worksheets:
 			rows = self.client.get_rows(self.sheet_id, worksheet)
 			for row_index, row in enumerate(rows):
 				# Skip first row (ie. the column titles).
@@ -200,7 +204,9 @@ class SheetsMiddleware():
 					self.write_value(row, "edit_link", edit_link)
 					self.mark_modified(row)
 
-				yield row
+				all_rows.append(row)
+		is_full = sorted(worksheets) == list(self.worksheets.keys()):
+		return is_full, all_rows
 
 	def write_id(self, row):
 		self.client.write_value(
diff --git a/sheetsync/sheetsync/streamlog.py b/sheetsync/sheetsync/streamlog.py
index 264303f..6ac0122 100644
--- a/sheetsync/sheetsync/streamlog.py
+++ b/sheetsync/sheetsync/streamlog.py
@@ -83,11 +83,14 @@ class StreamLogMiddleware:
 		}
 
 	def get_rows(self):
+		all_rows = []
 		for row in self.client.get_rows()["event_log"]:
 			row = self.parse_row(row)
 			# Malformed rows can be skipped, represented as a None result
 			if row is not None:
-				yield row
+				all_rows.append(row)
+		# There's no worksheet concept here so we always return a full sync.
+		return True, all_rows
 
 	def parse_row(self, row):
 		output = {}