diff --git a/zerver/lib/narrow.py b/zerver/lib/narrow.py
index d5747c0938..66d35cc068 100644
--- a/zerver/lib/narrow.py
+++ b/zerver/lib/narrow.py
@@ -909,14 +909,18 @@ def exclude_muting_conditions(
 
 
 def get_base_query_for_search(
-    user_profile: Optional[UserProfile], need_message: bool, need_user_message: bool
+    realm_id: int, user_profile: Optional[UserProfile], need_message: bool, need_user_message: bool
 ) -> Tuple[Select, ColumnElement[Integer]]:
     # Handle the simple case where user_message isn't involved first.
+    realm_cond = column("realm_id", Integer) == literal(realm_id)
     if not need_user_message:
         assert need_message
-        query = select(column("id", Integer).label("message_id")).select_from(
-            table("zerver_message")
+        query = (
+            select(column("id", Integer).label("message_id"))
+            .select_from(table("zerver_message"))
+            .where(realm_cond)
         )
+
         inner_msg_id_col = literal_column("zerver_message.id", Integer)
         return (query, inner_msg_id_col)
 
@@ -924,6 +928,7 @@ def get_base_query_for_search(
     if need_message:
         query = (
             select(column("message_id", Integer), column("flags", Integer))
+            .where(realm_cond)
             .where(column("user_profile_id", Integer) == literal(user_profile.id))
             .select_from(
                 join(
@@ -1004,6 +1009,7 @@ def find_first_unread_anchor(
     need_message = True
 
     query, inner_msg_id_col = get_base_query_for_search(
+        realm_id=user_profile.realm_id,
         user_profile=user_profile,
         need_message=need_message,
         need_user_message=need_user_message,
@@ -1278,6 +1284,7 @@ def fetch_messages(
 
     query: SelectBase
     query, inner_msg_id_col = get_base_query_for_search(
+        realm_id=realm.id,
         user_profile=user_profile,
         need_message=need_message,
         need_user_message=need_user_message,
diff --git a/zerver/tests/test_message_fetch.py b/zerver/tests/test_message_fetch.py
index b249e1c9fd..bd4e8adf42 100644
--- a/zerver/tests/test_message_fetch.py
+++ b/zerver/tests/test_message_fetch.py
@@ -3945,7 +3945,7 @@ recipient_id = %(recipient_id_3)s AND upper(subject) = upper(%(param_2)s))\
         hamlet_email = self.example_user("hamlet").email
         othello_email = self.example_user("othello").email
 
-        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE user_profile_id = {hamlet_id} AND (sender_id = {othello_id} AND recipient_id = {hamlet_recipient} OR sender_id = {hamlet_id} AND recipient_id = {othello_recipient}) AND message_id = 0) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE realm_id = 2 AND user_profile_id = {hamlet_id} AND (sender_id = {othello_id} AND recipient_id = {hamlet_recipient} OR sender_id = {hamlet_id} AND recipient_id = {othello_recipient}) AND message_id = 0) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {
@@ -3957,7 +3957,7 @@ recipient_id = %(recipient_id_3)s AND upper(subject) = upper(%(param_2)s))\
             sql,
         )
 
-        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE user_profile_id = {hamlet_id} AND (sender_id = {othello_id} AND recipient_id = {hamlet_recipient} OR sender_id = {hamlet_id} AND recipient_id = {othello_recipient}) AND message_id = 0) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE realm_id = 2 AND user_profile_id = {hamlet_id} AND (sender_id = {othello_id} AND recipient_id = {hamlet_recipient} OR sender_id = {hamlet_id} AND recipient_id = {othello_recipient}) AND message_id = 0) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {
@@ -3969,7 +3969,7 @@ recipient_id = %(recipient_id_3)s AND upper(subject) = upper(%(param_2)s))\
             sql,
         )
 
-        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE user_profile_id = {hamlet_id} AND (sender_id = {othello_id} AND recipient_id = {hamlet_recipient} OR sender_id = {hamlet_id} AND recipient_id = {othello_recipient}) ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE realm_id = 2 AND user_profile_id = {hamlet_id} AND (sender_id = {othello_id} AND recipient_id = {hamlet_recipient} OR sender_id = {hamlet_id} AND recipient_id = {othello_recipient}) ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {
@@ -3981,13 +3981,13 @@ recipient_id = %(recipient_id_3)s AND upper(subject) = upper(%(param_2)s))\
             sql,
         )
 
-        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE user_profile_id = {hamlet_id} AND (flags & 2) != 0 ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE realm_id = 2 AND user_profile_id = {hamlet_id} AND (flags & 2) != 0 ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {"anchor": 0, "num_before": 0, "num_after": 9, "narrow": '[["is", "starred"]]'}, sql
         )
 
-        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE user_profile_id = {hamlet_id} AND sender_id = {othello_id} ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE realm_id = 2 AND user_profile_id = {hamlet_id} AND sender_id = {othello_id} ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {
@@ -3999,20 +3999,20 @@ recipient_id = %(recipient_id_3)s AND upper(subject) = upper(%(param_2)s))\
             sql,
         )
 
-        sql_template = "SELECT anon_1.message_id \nFROM (SELECT id AS message_id \nFROM zerver_message \nWHERE recipient_id = {scotland_recipient} ORDER BY zerver_message.id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id \nFROM (SELECT id AS message_id \nFROM zerver_message \nWHERE realm_id = 2 AND recipient_id = {scotland_recipient} ORDER BY zerver_message.id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {"anchor": 0, "num_before": 0, "num_after": 9, "narrow": '[["stream", "Scotland"]]'},
             sql,
         )
 
-        sql_template = "SELECT anon_1.message_id \nFROM (SELECT id AS message_id \nFROM zerver_message \nWHERE recipient_id IN ({public_streams_recipients}) ORDER BY zerver_message.id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id \nFROM (SELECT id AS message_id \nFROM zerver_message \nWHERE realm_id = 2 AND recipient_id IN ({public_streams_recipients}) ORDER BY zerver_message.id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {"anchor": 0, "num_before": 0, "num_after": 9, "narrow": '[["streams", "public"]]'}, sql
         )
 
-        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE user_profile_id = {hamlet_id} AND (recipient_id NOT IN ({public_streams_recipients})) ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE realm_id = 2 AND user_profile_id = {hamlet_id} AND (recipient_id NOT IN ({public_streams_recipients})) ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {
@@ -4024,13 +4024,13 @@ recipient_id = %(recipient_id_3)s AND upper(subject) = upper(%(param_2)s))\
             sql,
         )
 
-        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE user_profile_id = {hamlet_id} AND upper(subject) = upper('blah') ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE realm_id = 2 AND user_profile_id = {hamlet_id} AND upper(subject) = upper('blah') ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {"anchor": 0, "num_before": 0, "num_after": 9, "narrow": '[["topic", "blah"]]'}, sql
         )
 
-        sql_template = "SELECT anon_1.message_id \nFROM (SELECT id AS message_id \nFROM zerver_message \nWHERE recipient_id = {scotland_recipient} AND upper(subject) = upper('blah') ORDER BY zerver_message.id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id \nFROM (SELECT id AS message_id \nFROM zerver_message \nWHERE realm_id = 2 AND recipient_id = {scotland_recipient} AND upper(subject) = upper('blah') ORDER BY zerver_message.id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {
@@ -4043,7 +4043,7 @@ recipient_id = %(recipient_id_3)s AND upper(subject) = upper(%(param_2)s))\
         )
 
         # Narrow to direct messages with yourself
-        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE user_profile_id = {hamlet_id} AND sender_id = {hamlet_id} AND recipient_id = {hamlet_recipient} ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE realm_id = 2 AND user_profile_id = {hamlet_id} AND sender_id = {hamlet_id} AND recipient_id = {hamlet_recipient} ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {
@@ -4055,7 +4055,7 @@ recipient_id = %(recipient_id_3)s AND upper(subject) = upper(%(param_2)s))\
             sql,
         )
 
-        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE user_profile_id = {hamlet_id} AND recipient_id = {scotland_recipient} AND (flags & 2) != 0 ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
+        sql_template = "SELECT anon_1.message_id, anon_1.flags \nFROM (SELECT message_id, flags \nFROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \nWHERE realm_id = 2 AND user_profile_id = {hamlet_id} AND recipient_id = {scotland_recipient} AND (flags & 2) != 0 ORDER BY message_id ASC \n LIMIT 10) AS anon_1 ORDER BY message_id ASC"
         sql = sql_template.format(**query_ids)
         self.common_check_get_messages_query(
             {
@@ -4079,7 +4079,7 @@ FROM unnest(string_to_array(ts_headline('zulip.english_us_search', rendered_cont
 FROM unnest(string_to_array(ts_headline('zulip.english_us_search', escape_html(subject), plainto_tsquery('zulip.english_us_search', 'jumping'), 'HighlightAll = TRUE, StartSel = <ts-match>, StopSel = </ts-match>'), '<ts-match>')) AS anon_5\n\
  LIMIT ALL OFFSET 1)) AS topic_matches \n\
 FROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \n\
-WHERE user_profile_id = {hamlet_id} AND (search_tsvector @@ plainto_tsquery('zulip.english_us_search', 'jumping')) ORDER BY message_id ASC \n\
+WHERE realm_id = 2 AND user_profile_id = {hamlet_id} AND (search_tsvector @@ plainto_tsquery('zulip.english_us_search', 'jumping')) ORDER BY message_id ASC \n\
  LIMIT 10) AS anon_1 ORDER BY message_id ASC\
 """
         sql = sql_template.format(**query_ids)
@@ -4095,7 +4095,7 @@ FROM unnest(string_to_array(ts_headline('zulip.english_us_search', rendered_cont
 FROM unnest(string_to_array(ts_headline('zulip.english_us_search', escape_html(subject), plainto_tsquery('zulip.english_us_search', 'jumping'), 'HighlightAll = TRUE, StartSel = <ts-match>, StopSel = </ts-match>'), '<ts-match>')) AS anon_5\n\
  LIMIT ALL OFFSET 1)) AS topic_matches \n\
 FROM zerver_message \n\
-WHERE recipient_id = {scotland_recipient} AND (search_tsvector @@ plainto_tsquery('zulip.english_us_search', 'jumping')) ORDER BY zerver_message.id ASC \n\
+WHERE realm_id = 2 AND recipient_id = {scotland_recipient} AND (search_tsvector @@ plainto_tsquery('zulip.english_us_search', 'jumping')) ORDER BY zerver_message.id ASC \n\
  LIMIT 10) AS anon_1 ORDER BY message_id ASC\
 """
         sql = sql_template.format(**query_ids)
@@ -4117,7 +4117,7 @@ FROM unnest(string_to_array(ts_headline('zulip.english_us_search', rendered_cont
 FROM unnest(string_to_array(ts_headline('zulip.english_us_search', escape_html(subject), plainto_tsquery('zulip.english_us_search', '"jumping" quickly'), 'HighlightAll = TRUE, StartSel = <ts-match>, StopSel = </ts-match>'), '<ts-match>')) AS anon_5\n\
  LIMIT ALL OFFSET 1)) AS topic_matches \n\
 FROM zerver_usermessage JOIN zerver_message ON zerver_usermessage.message_id = zerver_message.id \n\
-WHERE user_profile_id = {hamlet_id} AND (content ILIKE '%jumping%' OR subject ILIKE '%jumping%') AND (search_tsvector @@ plainto_tsquery('zulip.english_us_search', '"jumping" quickly')) ORDER BY message_id ASC \n\
+WHERE realm_id = 2 AND user_profile_id = {hamlet_id} AND (content ILIKE '%jumping%' OR subject ILIKE '%jumping%') AND (search_tsvector @@ plainto_tsquery('zulip.english_us_search', '"jumping" quickly')) ORDER BY message_id ASC \n\
  LIMIT 10) AS anon_1 ORDER BY message_id ASC\
 """
         sql = sql_template.format(**query_ids)