1 files changed, 92 insertions, 1 deletions

diff --git a/sql/handler.h b/sql/handler.h
index 65da0e69fca..b6124765b6b 100644
--- a/sql/handler.h
+++ b/sql/handler.h
@@ -35,6 +35,7 @@
 #include "sql_array.h"          /* Dynamic_array<> */
 #include "mdl.h"
 #include "vers_string.h"
+#include "backup.h"
 
 #include "sql_analyze_stmt.h" // for Exec_time_tracker 
 
@@ -1780,6 +1781,12 @@ handlerton *ha_default_tmp_handlerton(THD *thd);
 */
 #define HTON_REQUIRES_NOTIFY_TABLEDEF_CHANGED_AFTER_COMMIT (1 << 20)
 
+/*
+  Indicates that rename table is expensive operation.
+  When set atomic CREATE OR REPLACE TABLE is not used.
+*/
+#define HTON_EXPENSIVE_RENAME (1 << 21)
+
 class Ha_trx_info;
 
 struct THD_TRANS
@@ -2225,6 +2232,11 @@ struct Table_scope_and_contents_source_pod_st // For trivial members
   {
     bzero(this, sizeof(*this));
   }
+  /*
+    NOTE: share->tmp_table (tmp_table_type) is superset of this
+    HA_LEX_CREATE_TMP_TABLE which means TEMPORARY keyword in
+    CREATE TEMPORARY TABLE statement.
+  */
   bool tmp_table() const { return options & HA_LEX_CREATE_TMP_TABLE; }
   void use_default_db_type(THD *thd)
   {
@@ -2266,17 +2278,81 @@ struct Table_scope_and_contents_source_st:
   bool vers_check_system_fields(THD *thd, Alter_info *alter_info,
                                 const Lex_table_name &table_name,
                                 const Lex_table_name &db);
+};
+
+typedef struct st_ddl_log_state DDL_LOG_STATE;
+
+struct Atomic_info
+{
+  Table_name tmp_name;
+  Table_name backup_name;
+  DDL_LOG_STATE *ddl_log_state_create;
+  DDL_LOG_STATE *ddl_log_state_rm;
+  handlerton *old_hton;
+  backup_log_info drop_entry;
+
+  Atomic_info()
+  {
+    bzero(this, sizeof(*this));
+  }
 
+  Atomic_info(DDL_LOG_STATE *ddl_log_state_rm)
+  {
+    bzero(this, sizeof(*this));
+    Atomic_info::ddl_log_state_rm= ddl_log_state_rm;
+  }
+
+  bool is_atomic_replace() const
+  {
+    return tmp_name.table_name.str != NULL;
+  }
 };
 
 
+/*
+  mysql_create_table_no_lock can be called in one of the following
+  mutually exclusive situations:
+
+  - Just a normal ordinary CREATE TABLE statement that explicitly
+    defines the table structure.
+
+  - CREATE TABLE ... SELECT. It is special, because only in this case,
+    the list of fields is allowed to have duplicates, as long as one of the
+    duplicates comes from the select list, and the other doesn't. For
+    example in
+
+       CREATE TABLE t1 (a int(5) NOT NUL) SELECT b+10 as a FROM t2;
+
+    the list in alter_info->create_list will have two fields `a`.
+
+  - ALTER TABLE, that creates a temporary table #sql-xxx, which will be later
+    renamed to replace the original table.
+
+  - ALTER TABLE as above, but which only modifies the frm file, it only
+    creates an frm file for the #sql-xxx, the table in the engine is not
+    created.
+
+  - Assisted discovery, CREATE TABLE statement without the table structure.
+
+  These situations are distinguished by the following "create table mode"
+  values, except CREATE ... SELECT which is denoted by non-zero
+  Alter_info::select_field_count.
+*/
+
+#define C_ORDINARY_CREATE         0
+#define C_ALTER_TABLE             1
+#define C_ALTER_TABLE_FRM_ONLY    2
+#define C_ASSISTED_DISCOVERY      4
+
+
 /**
   This struct is passed to handler table routines, e.g. ha_create().
   It does not include the "OR REPLACE" and "IF NOT EXISTS" parts, as these
   parts are handled on the SQL level and are not needed on the handler level.
 */
 struct HA_CREATE_INFO: public Table_scope_and_contents_source_st,
-                       public Schema_specification_st
+                       public Schema_specification_st,
+                       public Atomic_info
 {
   /* TODO: remove after MDEV-20865 */
   Alter_info *alter_info;
@@ -2298,6 +2374,17 @@ struct HA_CREATE_INFO: public Table_scope_and_contents_source_st,
                   const Lex_table_charset_collation_attrs_st &default_cscl,
                   const Lex_table_charset_collation_attrs_st &convert_cscl,
                   const Charset_collation_context &ctx);
+  bool is_atomic_replace_usable() const
+  {
+    return !tmp_table() && !sequence &&
+           !(db_type->flags & HTON_EXPENSIVE_RENAME) &&
+           !DBUG_IF("ddl_log_expensive_rename");
+  }
+  bool finalize_atomic_replace(THD *thd, TABLE_LIST *orig_table);
+  void finalize_ddl(THD *thd, bool roll_back);
+  bool finalize_locked_tables(THD *thd);
+  bool make_tmp_table_list(THD *thd, TABLE_LIST **create_table,
+                           int *create_table_mode);
 };
 
 
@@ -2377,6 +2464,10 @@ struct Table_specification_st: public HA_CREATE_INFO,
                                                   convert_charset_collation,
                                                   ctx);
   }
+  bool is_atomic_replace() const
+  {
+    return or_replace() && is_atomic_replace_usable();
+  }
 };