Bug#27033: 0 as LAST_INSERT_ID() after INSERT .. ON DUPLICATE if rows were

touched but not actually changed.

The LAST_INSERT_ID() is reset to 0 if no rows were inserted or changed.
This is the case when an INSERT ... ON DUPLICATE KEY UPDATE updates a row
with the same values as the row contains.

Now the LAST_INSERT_ID() values is reset to 0 only if there were no rows
successfully inserted or touched.
The new 'touched' field is added to the COPY_INFO structure. It holds the
number of rows that were touched no matter whether they were actually
changed or not.


sql/sql_class.h:
  Bug#27033: 0 as LAST_INSERT_ID() after INSERT .. ON DUPLICATE if rows were
  touched but not actually changed.
  
  The new 'touched' field is added to the COPY_INFO structure. It holds the
  number of rows that were touched no matter whether they were actually
  changed or not.
mysql-test/r/insert_update.result:
  Added a test case for the bug#27033: 0 as LAST_INSERT_ID() after INSERT .. ON DUPLICATE if rows were
  touched but not actually changed.
mysql-test/t/insert_update.test:
  Added a test case for the bug#27033: 0 as LAST_INSERT_ID() after INSERT .. ON DUPLICATE if rows were
  touched but not actually changed.
sql/sql_insert.cc:
  Bug#27033: 0 as LAST_INSERT_ID() after INSERT .. ON DUPLICATE if rows were
  touched but not actually changed.
  
  Now the LAST_INSERT_ID() values is reset to 0 only if there were no rows
  successfully inserted or touched.

mysql-test/r/insert_update.result

@@ -236,3 +236,14 @@ INSERT INTO t2 VALUES (1), (3);
 INSERT INTO t1 SELECT 1, COUNT(*) FROM t2 ON DUPLICATE KEY UPDATE j= a;
 ERROR 42S22: Unknown column 'a' in 'field list'
 DROP TABLE t1,t2;
+CREATE TABLE t1 (f1 INT AUTO_INCREMENT PRIMARY KEY,
+f2 VARCHAR(5) NOT NULL UNIQUE);
+INSERT t1 (f2) VALUES ('test') ON DUPLICATE KEY UPDATE f1 = LAST_INSERT_ID(f1);
+SELECT LAST_INSERT_ID();
+LAST_INSERT_ID()
+1
+INSERT t1 (f2) VALUES ('test') ON DUPLICATE KEY UPDATE f1 = LAST_INSERT_ID(f1);
+SELECT LAST_INSERT_ID();
+LAST_INSERT_ID()
+1
+DROP TABLE t1;

mysql-test/t/insert_update.test

@@ -162,3 +162,15 @@ INSERT INTO t2 VALUES (1), (3);
 --error ER_BAD_FIELD_ERROR
 INSERT INTO t1 SELECT 1, COUNT(*) FROM t2 ON DUPLICATE KEY UPDATE j= a;
 DROP TABLE t1,t2;
+
+#
+# Bug#27033: 0 as LAST_INSERT_ID() after INSERT .. ON DUPLICATE if rows were
+#            touched but not actually changed.
+#
+CREATE TABLE t1 (f1 INT AUTO_INCREMENT PRIMARY KEY,
+                 f2 VARCHAR(5) NOT NULL UNIQUE);
+INSERT t1 (f2) VALUES ('test') ON DUPLICATE KEY UPDATE f1 = LAST_INSERT_ID(f1);
+SELECT LAST_INSERT_ID();
+INSERT t1 (f2) VALUES ('test') ON DUPLICATE KEY UPDATE f1 = LAST_INSERT_ID(f1);
+SELECT LAST_INSERT_ID();
+DROP TABLE t1;

sql/sql_class.h

@@ -356,13 +356,25 @@ class MYSQL_LOG: public TC_LOG
   inline uint32 get_open_count() { return open_count; }
 };
 
-
+/*
+  The COPY_INFO structure is used by INSERT/REPLACE code.
+  The schema of the row counting by the INSERT/INSERT ... ON DUPLICATE KEY
+  UPDATE code:
+    If a row is inserted then the copied variable is incremented.
+    If a row is updated by the INSERT ... ON DUPLICATE KEY UPDATE and the
+      new data differs from the old one then the copied and the updated
+      variables are incremented.
+    The touched variable is incremented if a row was touched by the update part
+      of the INSERT ... ON DUPLICATE KEY UPDATE no matter whether the row
+      was actually changed or not.
+*/
 typedef struct st_copy_info {
-  ha_rows records;
-  ha_rows deleted;
-  ha_rows updated;
-  ha_rows copied;
+  ha_rows records; /* Number of processed records */
+  ha_rows deleted; /* Number of deleted records */
+  ha_rows updated; /* Number of updated records */
+  ha_rows copied;  /* Number of copied records */
   ha_rows error_count;
+  ha_rows touched; /* Number of touched records */
   enum enum_duplicates handle_duplicates;
   int escape_char, last_errno;
   bool ignore;

sql/sql_insert.cc

@@ -522,7 +522,7 @@ bool mysql_insert(THD *thd,TABLE_LIST *table_list,
   /*
     Fill in the given fields and dump it to the table file
   */
-  info.records= info.deleted= info.copied= info.updated= 0;
+  info.records= info.deleted= info.copied= info.updated= info.touched= 0;
   info.ignore= ignore;
   info.handle_duplicates=duplic;
   info.update_fields= &update_fields;
@@ -767,8 +767,8 @@ bool mysql_insert(THD *thd,TABLE_LIST *table_list,
       (!table->triggers || !table->triggers->has_delete_triggers()))
     table->file->extra(HA_EXTRA_WRITE_CANNOT_REPLACE);
 
-  /* Reset value of LAST_INSERT_ID if no rows where inserted */
-  if (!info.copied && thd->insert_id_used)
+  /* Reset value of LAST_INSERT_ID if no rows were inserted or touched */
+  if (!info.copied && !info.touched && thd->insert_id_used)
   {
     thd->insert_id(0);
     id=0;
@@ -1221,14 +1221,16 @@ int write_record(THD *thd, TABLE *table,COPY_INFO *info)
           }
           goto err;
         }
-        if ((table->file->table_flags() & HA_PARTIAL_COLUMN_READ) ||
-            compare_record(table, thd->query_id))
-        {
-          info->updated++;
 
         if (table->next_number_field)
           table->file->adjust_next_insert_id_after_explicit_value(
             table->next_number_field->val_int());
+        info->touched++;
+
+        if ((table->file->table_flags() & HA_PARTIAL_COLUMN_READ) ||
+            compare_record(table, thd->query_id))
+        {
+          info->updated++;
 
           trg_error= (table->triggers &&
                       table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,