fix: flow handle reordered inserts (#5275)

* fix: reorder correct schema

* tests: reorder insert handled correctly

* chore: rm unused

* refactor: per review

* chore: more comment

* chore: per review

tests/cases/standalone/common/flow/flow_insert.sql

@@ -0,0 +1,96 @@
+-- test if reordered insert is correctly handled
+CREATE TABLE bytes_log (
+    byte INT,
+    ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    -- event time
+    TIME INDEX(ts)
+);
+
+-- TODO(discord9): remove this after auto infer table's time index is impl
+CREATE TABLE approx_rate (
+    rate DOUBLE,
+    time_window TIMESTAMP,
+    update_at TIMESTAMP,
+    TIME INDEX(time_window)
+);
+
+CREATE FLOW find_approx_rate SINK TO approx_rate AS
+SELECT
+    (max(byte) - min(byte)) / 30.0 as rate,
+    date_bin(INTERVAL '30 second', ts) as time_window
+from
+    bytes_log
+GROUP BY
+    time_window;
+
+SHOW CREATE TABLE approx_rate;
+
+-- reordered insert, also test if null is handled correctly
+INSERT INTO
+    bytes_log (ts, byte) 
+VALUES
+    ('2023-01-01 00:00:01', NULL),
+    ('2023-01-01 00:00:29', 300);
+
+-- SQLNESS REPLACE (ADMIN\sFLUSH_FLOW\('\w+'\)\s+\|\n\+-+\+\n\|\s+)[0-9]+\s+\| $1 FLOW_FLUSHED  |
+ADMIN FLUSH_FLOW('find_approx_rate');
+
+SELECT
+    rate,
+    time_window
+FROM
+    approx_rate;
+
+-- reordered insert, also test if null is handled correctly
+INSERT INTO
+    bytes_log (ts, byte) 
+VALUES
+    ('2022-01-01 00:00:01', NULL),
+    ('2022-01-01 00:00:29', NULL);
+
+-- SQLNESS REPLACE (ADMIN\sFLUSH_FLOW\('\w+'\)\s+\|\n\+-+\+\n\|\s+)[0-9]+\s+\| $1 FLOW_FLUSHED  |
+ADMIN FLUSH_FLOW('find_approx_rate');
+
+SELECT
+    rate,
+    time_window
+FROM
+    approx_rate;
+
+-- reordered insert
+INSERT INTO
+    bytes_log (ts, byte) 
+VALUES
+    ('2025-01-01 00:00:01', 101),
+    ('2025-01-01 00:00:29', 300);
+
+-- SQLNESS REPLACE (ADMIN\sFLUSH_FLOW\('\w+'\)\s+\|\n\+-+\+\n\|\s+)[0-9]+\s+\| $1 FLOW_FLUSHED  |
+ADMIN FLUSH_FLOW('find_approx_rate');
+
+SELECT
+    rate,
+    time_window
+FROM
+    approx_rate;
+
+-- reordered insert
+INSERT INTO
+    bytes_log (ts, byte) 
+VALUES
+    ('2025-01-01 00:00:32', 450),
+    ('2025-01-01 00:00:37', 500);
+
+-- SQLNESS REPLACE (ADMIN\sFLUSH_FLOW\('\w+'\)\s+\|\n\+-+\+\n\|\s+)[0-9]+\s+\| $1 FLOW_FLUSHED  |
+ADMIN FLUSH_FLOW('find_approx_rate');
+
+SELECT
+    rate,
+    time_window
+FROM
+    approx_rate;
+
+DROP TABLE bytes_log;
+
+DROP FLOW find_approx_rate;
+
+DROP TABLE approx_rate;