MDEV-29872 MSAN/Valgrind uninitialised value errors in TABLE::vers_switch_partition

Delayed_insert has its own THD (initialized at mysql_insert()) and
hence its own LEX. Delayed_insert initalizes a very few parameters for
LEX and 'duplicates' is not in this list. Now we copy this missing
parameter from parser LEX (as well as sql_command).

mysql-test/suite/versioning/r/partition.result

@@ -3463,6 +3463,11 @@ unlock tables;
 drop table t1, t2;
 set timestamp= default;
 #
+# MDEV-29872 MSAN/Valgrind uninitialised value errors in TABLE::vers_switch_partition
+#
+create table t (a int) with system versioning partition by system_time limit 100 partitions 3;
+drop table t;
+#
 # End of 10.9 tests
 #
 set global innodb_stats_persistent= @save_persistent;

mysql-test/suite/versioning/t/partition.test

@@ -2690,6 +2690,23 @@ unlock tables;
 drop table t1, t2;
 set timestamp= default;
 
+--echo #
+--echo # MDEV-29872 MSAN/Valgrind uninitialised value errors in TABLE::vers_switch_partition
+--echo #
+create table t (a int) with system versioning partition by system_time limit 100 partitions 3;
+let $emb= `select if(version() like '%embedded%', 1, 0)`;
+if (!$emb)
+{
+  --disable_result_log
+  --disable_query_log
+  --error ER_DELAYED_NOT_SUPPORTED
+  insert delayed into t () values ();
+  --enable_query_log
+  --enable_result_log
+}
+# cleanup
+drop table t;
+
 --echo #
 --echo # End of 10.9 tests
 --echo #

sql/sql_insert.cc

@@ -2401,7 +2401,7 @@ class Delayed_insert :public ilink {
     passed from connection thread to the handler thread.
   */
   MDL_request grl_protection;
-  Delayed_insert(SELECT_LEX *current_select)
+  Delayed_insert(LEX *lex)
     :locks_in_memory(0), thd(next_thread_id()),
      table(0),tables_in_use(0), stacked_inserts(0),
      status(0), retry(0), handler_thread_initialized(FALSE), group_count(0)
@@ -2414,8 +2414,9 @@ class Delayed_insert :public ilink {
     strmake_buf(thd.security_ctx->priv_user, thd.security_ctx->user);
     thd.current_tablenr=0;
     thd.set_command(COM_DELAYED_INSERT);
-    thd.lex->current_select= current_select;
-    thd.lex->sql_command= SQLCOM_INSERT;        // For innodb::store_lock()
+    thd.lex->current_select= lex->current_select;
+    thd.lex->sql_command= lex->sql_command;        // For innodb::store_lock()
+    thd.lex->duplicates= lex->duplicates;
     /*
       Prevent changes to global.lock_wait_timeout from affecting
       delayed insert threads as any timeouts in delayed inserts
@@ -2591,7 +2592,7 @@ bool delayed_get_table(THD *thd, MDL_request *grl_protection_request,
     */
     if (! (di= find_handler(thd, table_list)))
     {
-      if (!(di= new Delayed_insert(thd->lex->current_select)))
+      if (!(di= new Delayed_insert(thd->lex)))
         goto end_create;
 
       /*