diff --git a/src/Storages/MergeTree/KeyCondition.cpp b/src/Storages/MergeTree/KeyCondition.cpp
index 57d9c86f102..6847a09b85c 100644
--- a/src/Storages/MergeTree/KeyCondition.cpp
+++ b/src/Storages/MergeTree/KeyCondition.cpp
@@ -1089,7 +1089,7 @@ BoolMask KeyCondition::checkInRange(
 /*      std::cerr << "Hyperrectangle: ";
         for (size_t i = 0, size = key_ranges.size(); i != size; ++i)
             std::cerr << (i != 0 ? " x " : "") << key_ranges[i].toString();
-        std::cerr << ": " << res << "\n";*/
+        std::cerr << ": " << res.can_be_true << "\n";*/
 
         return res;
     });
@@ -1112,10 +1112,20 @@ std::optional<Range> KeyCondition::applyMonotonicFunctionsChainToRange(
             return {};
         }
 
+        /// If we apply function to open interval, we can get empty intervals in result.
+        /// E.g. for ('2020-01-03', '2020-01-20') after applying 'toYYYYMM' we will get ('202001', '202001').
+        /// To avoid this we make range left and right included.
         if (!key_range.left.isNull())
+        {
             key_range.left = applyFunction(func, current_type, key_range.left);
+            key_range.left_included = true;
+        }
+
         if (!key_range.right.isNull())
+        {
             key_range.right = applyFunction(func, current_type, key_range.right);
+            key_range.right_included = true;
+        }
 
         current_type = func->getReturnType();
 
diff --git a/tests/queries/0_stateless/01418_index_analysis_bug.reference b/tests/queries/0_stateless/01418_index_analysis_bug.reference
new file mode 100644
index 00000000000..54a57d63d56
--- /dev/null
+++ b/tests/queries/0_stateless/01418_index_analysis_bug.reference
@@ -0,0 +1,24 @@
+2020-07-03	706
+2020-07-04	695
+2020-07-05	726
+2020-07-06	686
+2020-07-07	715
+2020-07-08	706
+2020-07-09	695
+2020-07-10	726
+2020-07-11	686
+2020-07-12	715
+2020-07-13	706
+2020-07-14	695
+2020-07-15	726
+2020-07-16	686
+2020-07-17	715
+2020-07-18	706
+2020-07-19	695
+2020-07-20	726
+2020-07-21	686
+2020-07-22	715
+2020-07-23	706
+2020-07-24	695
+2020-07-25	726
+2
diff --git a/tests/queries/0_stateless/01418_index_analysis_bug.sql b/tests/queries/0_stateless/01418_index_analysis_bug.sql
new file mode 100644
index 00000000000..c5033ac7d96
--- /dev/null
+++ b/tests/queries/0_stateless/01418_index_analysis_bug.sql
@@ -0,0 +1,43 @@
+DROP TABLE IF EXISTS mytable_local;
+
+CREATE TABLE mytable_local (
+    created          DateTime,
+    eventday         Date,
+    user_id          UInt32
+)
+ENGINE = MergeTree()
+PARTITION BY toYYYYMM(eventday)
+ORDER BY (eventday, user_id);
+
+INSERT INTO mytable_local SELECT 
+    toDateTime('2020-06-01 00:00:00') + toIntervalMinute(number) AS created,
+    toDate(created) AS eventday,
+    if((number % 100) > 50, 742522, number % 32141) AS user_id
+FROM numbers(100000);
+
+SELECT 
+    eventday,
+    count(*)
+FROM mytable_local
+WHERE (toYYYYMM(eventday) = 202007) AND (user_id = 742522) AND (eventday >= '2020-07-03') AND (eventday <= '2020-07-25')
+GROUP BY eventday
+ORDER BY eventday;
+
+DROP TABLE mytable_local;
+DROP TABLE IF EXISTS table_float;
+
+CREATE TABLE table_float
+(
+    f Float64,
+    u UInt32
+)
+ENGINE = MergeTree
+ORDER BY (f, u);
+
+INSERT INTO table_float VALUES (1.2, 1) (1.3, 2) (1.4, 3) (1.5, 4);
+
+SELECT count()
+FROM table_float
+WHERE (toUInt64(f) = 1) AND (f >= 1.3) AND (f <= 1.4) AND (u > 0);
+
+DROP TABLE table_float;