BUG#21726: Incorrect result with multiple invocations of LAST_INSERT_ID

Non-upper-level INSERTs (the ones in the body of stored procedure,
stored function, or trigger) into a table that have AUTO_INCREMENT
column didn't affected the result of LAST_INSERT_ID() on this level.

The problem was introduced with the fix of bug 6880, which in turn was
introduced with the fix of bug 3117, where current insert_id value was
remembered on the first call to LAST_INSERT_ID() (bug 3117) and was
returned from that function until it was reset before the next
_upper-level_ statement (bug 6880).

The fix for bug#21726 brings back the behaviour of version 4.0, and
implements the following: remember insert_id value at the beginning
of the statement or expression (which at that point equals to
the first insert_id value generated by the previous statement), and
return that remembered value from LAST_INSERT_ID() or @@LAST_INSERT_ID.

Thus, the value returned by LAST_INSERT_ID() is not affected by values
generated by current statement, nor by LAST_INSERT_ID(expr) calls in
this statement.

Version 5.1 does not have this bug (it was fixed by WL 3146).

1 files changed, 33 insertions, 15 deletions

diff --git a/sql/sql_class.h b/sql/sql_class.h
index 039c133e885..ccc7a661446 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -1252,17 +1252,29 @@ public:
   ulonglong  next_insert_id;
   /* Remember last next_insert_id to reset it if something went wrong */
   ulonglong  prev_insert_id;
+
   /*
-    The insert_id used for the last statement or set by SET LAST_INSERT_ID=#
-    or SELECT LAST_INSERT_ID(#).  Used for binary log and returned by
-    LAST_INSERT_ID()
+    At the beginning of the statement last_insert_id holds the first
+    generated value of the previous statement.  During statement
+    execution it is updated to the value just generated, but then
+    restored to the value that was generated first, so for the next
+    statement it will again be "the first generated value of the
+    previous statement".
+
+    It may also be set with "LAST_INSERT_ID(expr)" or
+    "@@LAST_INSERT_ID= expr", but the effect of such setting will be
+    seen only in the next statement.
   */
   ulonglong  last_insert_id;
+
   /*
-    Set to the first value that LAST_INSERT_ID() returned for the last
-    statement.  When this is set, last_insert_id_used is set to true.
+    current_insert_id remembers the first generated value of the
+    previous statement, and does not change during statement
+    execution.  Its value returned from LAST_INSERT_ID() and
+    @@LAST_INSERT_ID.
   */
   ulonglong  current_insert_id;
+
   ulonglong  limit_found_rows;
   ulonglong  options;           /* Bitmap of states */
   longlong   row_count_func;	/* For the ROW_COUNT() function */
@@ -1325,7 +1337,22 @@ public:
   bool       last_cuted_field;
   bool	     no_errors, password, is_fatal_error;
   bool	     query_start_used, rand_used, time_zone_used;
-  bool	     last_insert_id_used,insert_id_used, clear_next_insert_id;
+
+  /*
+    last_insert_id_used is set when current statement calls
+    LAST_INSERT_ID() or reads @@LAST_INSERT_ID, so that binary log
+    LAST_INSERT_ID_EVENT be generated.
+  */
+  bool	     last_insert_id_used;
+
+  /*
+    insert_id_used is set when current statement updates
+    THD::last_insert_id, so that binary log INSERT_ID_EVENT be
+    generated.
+  */
+  bool       insert_id_used;
+
+  bool       clear_next_insert_id;
   /* for IS NULL => = last_insert_id() fix in remove_eq_conds() */
   bool       substitute_null_with_insert_id;
   bool	     in_lock_tables;
@@ -1461,15 +1488,6 @@ public:
     insert_id_used=1;
     substitute_null_with_insert_id= TRUE;
   }
-  inline ulonglong insert_id(void)
-  {
-    if (!last_insert_id_used)
-    {
-      last_insert_id_used=1;
-      current_insert_id=last_insert_id;
-    }
-    return last_insert_id;
-  }
   inline ulonglong found_rows(void)
   {
     return limit_found_rows;