MDEV-38839 Assertion (thd->state_flags & Open_tables_state::BACKUPS_A…

mysql-test/suite/binlog/r/binlog_bug38839.result

@@ -0,0 +1,11 @@
+SET sql_mode='';
+CREATE TEMPORARY TABLE t ENGINE=MyISAM AS SELECT @a AS c;
+INSERT INTO t VALUES (0xABB0);
+SET autocommit=OFF;
+CREATE TABLE t (c INT PRIMARY KEY) ENGINE=MyISAM SELECT * FROM t FOR UPDATE;
+ERROR 23000: Duplicate entry '0' for key 'PRIMARY'
+SET autocommit=ON;
+DROP TEMPORARY TABLE IF EXISTS t;
+DROP TABLE IF EXISTS t;
+Warnings:
+Note	1051	Unknown table 'test.t'

mysql-test/suite/binlog/t/binlog_bug38839.test

@@ -0,0 +1,17 @@
+# Test case for MDEV-38839
+# Assertion `(thd->state_flags & Open_tables_state::BACKUPS_AVAIL) ||
+# !thd->has_pending_row_events()' failed in close_thread_tables
+# on CREATE TABLE ... SELECT * FROM temp_table FOR UPDATE in MIXED binlog mode
+
+--source include/have_log_bin.inc
+--source include/have_binlog_format_mixed.inc
+
+SET sql_mode='';
+CREATE TEMPORARY TABLE t ENGINE=MyISAM AS SELECT @a AS c;
+INSERT INTO t VALUES (0xABB0);
+SET autocommit=OFF;
+--error ER_DUP_ENTRY
+CREATE TABLE t (c INT PRIMARY KEY) ENGINE=MyISAM SELECT * FROM t FOR UPDATE;
+SET autocommit=ON;
+DROP TEMPORARY TABLE IF EXISTS t;
+DROP TABLE IF EXISTS t;

sql/sql_class.cc

@@ -7130,7 +7130,7 @@ int THD::decide_logging_format(TABLE_LIST *tables)
         }
       }
 
-      if (tbl->lock_type >= TL_FIRST_WRITE)
+      if (tbl->updating)
       {
         bool trans;
         if (prev_write_table && prev_write_table->file->ht !=
@@ -7147,12 +7147,29 @@ int THD::decide_logging_format(TABLE_LIST *tables)
 
         trans= table->file->has_transactions();
 
-        if (share->tmp_table)
-          lex->set_stmt_accessed_table(trans ? LEX::STMT_WRITES_TEMP_TRANS_TABLE :
-                                               LEX::STMT_WRITES_TEMP_NON_TRANS_TABLE);
-        else
-          lex->set_stmt_accessed_table(trans ? LEX::STMT_WRITES_TRANS_TABLE :
-                                               LEX::STMT_WRITES_NON_TRANS_TABLE);
+        /*
+          For SELECT ... FOR UPDATE, tbl->updating is false because the
+          table is only locked for reading, not actually being modified.
+          MyISAM has no row-level locking so FOR UPDATE escalates to
+          TL_WRITE, but this does not mean the table is being written to.
+          Sequences are an exception: even though tbl->updating is false
+          for SELECT NEXT VALUE FOR s, the sequence table is genuinely
+          modified internally, which is indicated by tbl->sequence.
+          Only set the write flag when the table is actually being written
+          to (tbl->updating) or is a sequence (tbl->sequence), to avoid
+          incorrectly setting MODIFIED_NON_TRANS_TABLE which would block
+          binlog_truncate_trx_cache() in MIXED mode and cause an assertion
+          in close_thread_tables().
+        */
+        // if (tbl->updating || tbl->sequence)
+        // {
+          if (share->tmp_table)
+            lex->set_stmt_accessed_table(trans ? LEX::STMT_WRITES_TEMP_TRANS_TABLE :
+                                                 LEX::STMT_WRITES_TEMP_NON_TRANS_TABLE);
+          else
+            lex->set_stmt_accessed_table(trans ? LEX::STMT_WRITES_TRANS_TABLE :
+                                                 LEX::STMT_WRITES_NON_TRANS_TABLE);
+        // }
 
         flags_write_all_set &= flags;
         flags_write_some_set |= flags;

sql/sql_parse.cc

@@ -8185,6 +8185,11 @@ TABLE_LIST *st_select_lex::add_table_to_list(THD *thd,
   if (!ptr->table_name.str)
     DBUG_RETURN(0); // EOM
 
+  if (ptr->sequence)
+  {
+    ptr->updating= true;
+  }
+
   /* check that used name is unique. Sequences are ignored */
   if (lock_type != TL_IGNORE && !ptr->sequence)
   {

sql/sql_table.cc

@@ -10913,6 +10913,7 @@ bool mysql_alter_table(THD *thd, const LEX_CSTRING *new_db,
   if (online)
   {
     table_list->lock_type= TL_READ;
+    table_list->updating = false;
   }
 
   enum_tx_isolation iso_level_initial= thd->tx_isolation;