MDEV-27027 Atomic DDL: Assertion failed upon unsuccessful multi-RENAM…

mysql-test/main/rename.result

@@ -173,3 +173,43 @@ drop table t2;
 rename table if exists t1 to t2;
 alter table if exists t2 rename to t1;
 drop table t1;
+#
+# MDEV-27027 Atomic DDL: Assertion `!param->got_error' failed upon
+#             unsuccessful multi-RENAME TABLE
+#
+CREATE TABLE t1 (a INT);
+CREATE TRIGGER tr1 AFTER INSERT ON t1 FOR EACH ROW
+INSERT INTO db.t SELECT SLEEP(0.05);
+# Missing table in RENAME TABLE (should error)
+RENAME TABLE t1 TO t2,
+missing1 TO m1;
+ERROR 42S02: Table 'test.missing1' doesn't exist
+SHOW CREATE TRIGGER tr1;
+Trigger	sql_mode	SQL Original Statement	character_set_client	collation_connection	Database Collation	Created
+tr1	STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	CREATE DEFINER=`root`@`localhost` TRIGGER tr1 AFTER INSERT ON `t1` FOR EACH ROW
+INSERT INTO db.t SELECT SLEEP(0.05)	latin1	latin1_swedish_ci	latin1_swedish_ci	#
+CREATE TABLE t2 (a INT);
+# Attempt to rename to existing table (should error)
+RENAME TABLE t2 TO t3,
+t1 TO t3;
+ERROR 42S01: Table 't3' already exists
+SHOW CREATE TRIGGER tr1;
+Trigger	sql_mode	SQL Original Statement	character_set_client	collation_connection	Database Collation	Created
+tr1	STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	CREATE DEFINER=`root`@`localhost` TRIGGER tr1 AFTER INSERT ON `t1` FOR EACH ROW
+INSERT INTO db.t SELECT SLEEP(0.05)	latin1	latin1_swedish_ci	latin1_swedish_ci	#
+# Test multiple warnings captured during renaming
+RENAME TABLE IF EXISTS
+missing1 TO m1,
+missing2 TO m2,
+t2 TO t3,  # this rename succeeds
+missing3 TO m3;
+Warnings:
+Note	1146	Table 'test.missing1' doesn't exist
+Note	1146	Table 'test.missing2' doesn't exist
+Note	1146	Table 'test.missing3' doesn't exist
+RENAME TABLE IF EXISTS
+missing1 TO m1,
+t1 TO t3,  # this will error: table exists
+missing2 TO m2;
+ERROR 42S01: Table 't3' already exists
+DROP TABLE t1, t3;

mysql-test/main/rename.test

@@ -166,3 +166,44 @@ drop table t2;
 rename table if exists t1 to t2;
 alter table if exists t2 rename to t1;
 drop table t1;
+
+--echo #
+--echo # MDEV-27027 Atomic DDL: Assertion `!param->got_error' failed upon
+--echo #             unsuccessful multi-RENAME TABLE
+--echo #
+CREATE TABLE t1 (a INT);
+CREATE TRIGGER tr1 AFTER INSERT ON t1 FOR EACH ROW
+  INSERT INTO db.t SELECT SLEEP(0.05);
+
+--echo # Missing table in RENAME TABLE (should error)
+--error ER_NO_SUCH_TABLE
+RENAME TABLE t1 TO t2,
+             missing1 TO m1; # this will error: missing table
+
+--replace_column 7 #
+SHOW CREATE TRIGGER tr1;
+
+CREATE TABLE t2 (a INT);
+
+--echo # Attempt to rename to existing table (should error)
+--error ER_TABLE_EXISTS_ERROR
+RENAME TABLE t2 TO t3,
+             t1 TO t3; # this will error: table exists
+
+--replace_column 7 #
+SHOW CREATE TRIGGER tr1;
+
+--echo # Test multiple warnings captured during renaming
+RENAME TABLE IF EXISTS
+  missing1 TO m1,
+  missing2 TO m2,
+  t2 TO t3,  # this rename succeeds
+  missing3 TO m3;
+
+--error ER_TABLE_EXISTS_ERROR
+RENAME TABLE IF EXISTS
+  missing1 TO m1,
+  t1 TO t3,  # this will error: table exists
+  missing2 TO m2;
+
+DROP TABLE t1, t3;

sql/sql_class.h

@@ -2047,6 +2047,76 @@ class Counting_error_handler : public Internal_error_handler
 };
 
 
+extern "C" void my_message_sql(uint error, const char *str, myf MyFlags);
+
+/**
+  Error handler that captures and postpones errors.
+  Warnings and notes are passed through to the next handler.
+  Stored errors can be re-emitted later via emit_errors().
+*/
+
+class Postponed_error_handler : public Internal_error_handler
+{
+  struct Error_entry
+  {
+    uint sql_errno;
+    char message[MYSQL_ERRMSG_SIZE];
+    Error_entry *next;
+  };
+
+  Error_entry *m_first;
+  Error_entry *m_last;
+  MEM_ROOT *m_mem_root;
+
+public:
+  Postponed_error_handler(MEM_ROOT *mem_root)
+    : m_first(nullptr), m_last(nullptr), m_mem_root(mem_root)
+  {}
+
+  bool handle_condition(THD *thd,
+                        uint sql_errno,
+                        const char *sqlstate,
+                        Sql_condition::enum_warning_level *level,
+                        const char *msg,
+                        Sql_condition **cond_hdl) override
+  {
+    /* Only capture errors, let warnings and notes pass through */
+    if (*level != Sql_condition::WARN_LEVEL_ERROR)
+      return false;
+
+    Error_entry *entry= (Error_entry*) alloc_root(m_mem_root,
+                                                  sizeof(Error_entry));
+    if (!entry)
+      return false;  // Can't store, let error propagate
+
+    entry->sql_errno= sql_errno;
+    strmake(entry->message, msg, sizeof(entry->message) - 1);
+    entry->next= nullptr;
+
+    if (m_last)
+      m_last->next= entry;
+    else
+      m_first= entry;
+    m_last= entry;
+
+    return true;
+  }
+
+  bool has_errors() const { return m_first != nullptr; }
+
+  void emit_errors()
+  {
+    for (Error_entry *e= m_first; e; e= e->next)
+      my_message_sql(e->sql_errno, e->message, MYF(0));
+  }
+
+  void clear()
+  {
+    m_first= m_last= nullptr;
+  }
+};
+
+
 /**
   This class is an internal error handler implementation for
   DROP TABLE statements. The thing is that there may be warnings during

sql/sql_rename.cc

@@ -20,6 +20,7 @@
 */
 
 #include "mariadb.h"
+#include "sql_class.h"
 #include "sql_priv.h"
 #include "unireg.h"
 #include "sql_rename.h"
@@ -51,6 +52,7 @@ static bool rename_tables(THD *thd, TABLE_LIST *table_list,
   the new name.
 */
 
+
 bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent,
                           bool if_exists)
 {
@@ -60,6 +62,7 @@ bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent,
   int to_table;
   const char *rename_log_table[2]= {NULL, NULL};
   DDL_LOG_STATE ddl_log_state;
+  Postponed_error_handler postponed_handler(thd->mem_root);
   DBUG_ENTER("mysql_rename_tables");
 
   /*
@@ -162,6 +165,15 @@ bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent,
     An exclusive lock on table names is satisfactory to ensure
     no other thread accesses this table.
   */
+
+  /*
+    Do not emit errors which may occur during the sequence of renamings,
+    because they will raise the 'thd->is_error()' flag, and `ddl_log_revert()`
+    may fail due to this. Instead, capture and collect errors and warnings
+    and emit them only after the renaming and possible reversion are complete.
+  */
+  thd->push_internal_handler(&postponed_handler);
+
   error= rename_tables(thd, table_list, &ddl_log_state,
                        0, if_exists, &force_if_exists);
 
@@ -192,6 +204,7 @@ bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent,
       my_ok(thd);
   }
 
+  thd->pop_internal_handler();
   if (likely(!error))
   {
     query_cache_invalidate3(thd, table_list, 0);
@@ -201,6 +214,7 @@ bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent,
   {
     /* Revert the renames of normal tables with the help of the ddl log */
     ddl_log_revert(thd, &ddl_log_state);
+    postponed_handler.emit_errors();
   }
 
 err: