From b317ede07adb3d9906b2e73873d7948557581b7b Mon Sep 17 00:00:00 2001
From: ARaveala <arandomsanti@gmail.com>
Date: Thu, 21 May 2026 11:49:47 +0300
Subject: [PATCH] MDEV-39597: Remove save/restore of proc_info in
 free_tmp_table

SHOW PROFILE reports duplicate stage entries for INSERT...SELECT
caused by a save/restore pattern in free_tmp_table that blindly
restores the previous stage name after tmp table removal.

The fix removes the save/restore. The 'Removing tmp table' stage
now remains active until the caller sets the next stage.

Test uses --disable_ps2_protocol following the pattern in
show_profile.test to ensure consistent QUERY_ID in PS protocol mode.

fixup: add trailing newline to test file
---
 mysql-test/main/mdev-39597.result | 31 ++++++++++++++++++++++++
 mysql-test/main/mdev-39597.test   | 39 +++++++++++++++++++++++++++++++
 sql/sql_select.cc                 |  3 ---
 3 files changed, 70 insertions(+), 3 deletions(-)
 create mode 100644 mysql-test/main/mdev-39597.result
 create mode 100644 mysql-test/main/mdev-39597.test

diff --git a/mysql-test/main/mdev-39597.result b/mysql-test/main/mdev-39597.result
new file mode 100644
index 0000000000000..92ba163050642
--- /dev/null
+++ b/mysql-test/main/mdev-39597.result
@@ -0,0 +1,31 @@
+#
+# MDEV-39597: SHOW PROFILE reports duplicate sending data
+# stage for INSERT...SELECT due to save/restore in free_tmp_table
+#
+CREATE TABLE profile_test (
+id INT PRIMARY KEY AUTO_INCREMENT,
+name VARCHAR(100),
+value INT
+);
+INSERT INTO profile_test (name, value) VALUES
+('alpha',1),('beta',2),('gamma',3),('delta',4),('epsilon',5),
+('zeta',6),('eta',7),('theta',8),('iota',9),('kappa',10);
+SET profiling = 1;
+INSERT INTO profile_test (name, value)
+SELECT name, value FROM profile_test LIMIT 5;
+# Check that no stage appears twice consecutively around removing tmp table
+SELECT COUNT(*) AS duplicate_stage_found
+FROM (
+SELECT
+STATE,
+LAG(STATE) OVER (ORDER BY SEQ) AS prev_status,
+LEAD(STATE) OVER (ORDER BY SEQ) AS next_status
+FROM information_schema.profiling
+WHERE QUERY_ID = 1
+) t
+WHERE STATE = 'Removing tmp table'
+AND prev_status = next_status;
+duplicate_stage_found
+0
+SET profiling = 0;
+DROP TABLE profile_test;
diff --git a/mysql-test/main/mdev-39597.test b/mysql-test/main/mdev-39597.test
new file mode 100644
index 0000000000000..62b8c5b38f2b4
--- /dev/null
+++ b/mysql-test/main/mdev-39597.test
@@ -0,0 +1,39 @@
+--echo #
+--echo # MDEV-39597: SHOW PROFILE reports duplicate sending data
+--echo # stage for INSERT...SELECT due to save/restore in free_tmp_table
+--echo #
+
+--source include/have_profiling.inc
+--disable_ps2_protocol
+
+CREATE TABLE profile_test (
+  id INT PRIMARY KEY AUTO_INCREMENT,
+  name VARCHAR(100),
+  value INT
+);
+INSERT INTO profile_test (name, value) VALUES
+  ('alpha',1),('beta',2),('gamma',3),('delta',4),('epsilon',5),
+  ('zeta',6),('eta',7),('theta',8),('iota',9),('kappa',10);
+SET profiling = 1;
+INSERT INTO profile_test (name, value)
+  SELECT name, value FROM profile_test LIMIT 5;
+
+--echo # Check that no stage appears twice consecutively around removing tmp table
+
+SELECT COUNT(*) AS duplicate_stage_found
+FROM (
+  SELECT
+    STATE,
+    LAG(STATE) OVER (ORDER BY SEQ) AS prev_status,
+    LEAD(STATE) OVER (ORDER BY SEQ) AS next_status
+  FROM information_schema.profiling
+  WHERE QUERY_ID = 1
+) t
+WHERE STATE = 'Removing tmp table'
+AND prev_status = next_status;
+
+--enable_ps2_protocol
+
+# clean up
+SET profiling = 0;
+DROP TABLE profile_test;
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 70785f531bb00..90763725f8b8e 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -22321,12 +22321,10 @@ void
 free_tmp_table(THD *thd, TABLE *entry)
 {
   MEM_ROOT own_root= entry->mem_root;
-  const char *save_proc_info;
   DBUG_ENTER("free_tmp_table");
   DBUG_PRINT("enter",("table: %s  alias: %s",entry->s->table_name.str,
                       entry->alias.c_ptr()));
 
-  save_proc_info=thd->proc_info;
   THD_STAGE_INFO(thd, stage_removing_tmp_table);
 
   if (entry->file && entry->is_created())
@@ -22362,7 +22360,6 @@ free_tmp_table(THD *thd, TABLE *entry)
   }
 
   free_root(&own_root, MYF(0)); /* the table is allocated in its own root */
-  thd_proc_info(thd, save_proc_info);
 
   DBUG_VOID_RETURN;
 }