MySQL-8.0 | 数据字典最强解读

SET SESSION debug='+d,skip_dd_table_access_check';select name from mysql.tables where hidden='System' and type='BASE TABLE';
+------------------------------+
| name                         |
+------------------------------+
| dd_properties                |
| innodb_dynamic_metadata      |
| innodb_ddl_log               |
| catalogs                     |
| character_sets               |
| collations                   |
| column_statistics            |
| column_type_elements         |
| columns                      |
| events                       |
| foreign_key_column_usage     |
| foreign_keys                 |
| index_column_usage           |
| index_partitions             |
| index_stats                  |
| indexes                      |
| parameter_type_elements      |
| parameters                   |
| resource_groups              |
| routines                     |
| schemata                     |
| st_spatial_reference_systems |
| table_partition_values       |
| table_partitions             |
| table_stats                  |
| tables                       |
| tablespace_files             |
| tablespaces                  |
| triggers                     |
| view_routine_usage           |
| view_table_usage             |
+------------------------------+
31 rows in set (0.01 sec)

show variables like '%definition%';
+---------------------------------+-------+
| Variable_name                   | Value |
+---------------------------------+-------+
| schema_definition_cache         | 256   |
| stored_program_definition_cache | 256   |
| table_definition_cache          | 2000  |
| tablespace_definition_cache     | 256   |
+---------------------------------+-------+

class Shared_dictionary_cache
{
...
 Shared_multi_map<Abstract_table> m_abstract_table_map;
 Shared_multi_map<Charset> m_charset_map;
 Shared_multi_map<Collation> m_collation_map;
 Shared_multi_map<Column_statistics> m_column_stat_map;
 Shared_multi_map<Event> m_event_map;
 Shared_multi_map<Resource_group> m_resource_group_map;
 Shared_multi_map<Routine> m_routine_map;
 Shared_multi_map<Schema> m_schema_map;
 Shared_multi_map<Spatial_reference_system> m_spatial_reference_system_map;
 Shared_multi_map<Tablespace> m_tablespace_map;
...
}

show create table SCHEMATA\G
*************************** 1. row ***************************
             View: SCHEMATA
      Create View: CREATE ALGORITHM=UNDEFINED DEFINER=`mysql.infoschema`@`localhost` SQL SECURITY DEFINER VIEW `SCHEMATA` AS select `cat`.`name` AS `CATALOG_NAME`,`sch`.`name` AS `SCHEMA_NAME`,`cs`.`name` AS `DEFAULT_CHARACTER_SET_NAME`,`col`.`name` AS `DEFAULT_COLLATION_NAME`,NULL AS `SQL_PATH` from (((`mysql`.`schemata` `sch` join `mysql`.`catalogs` `cat` on((`cat`.`id` = `sch`.`catalog_id`))) join `mysql`.`collations` `col` on((`sch`.`default_collation_id` = `col`.`id`))) join `mysql`.`character_sets` `cs` on((`col`.`character_set_id` = `cs`.`id`))) where can_access_database(`sch`.`name`)
character_set_client: utf8
collation_connection: utf8_general_ci
1 row in set (0.00 sec)

EXPLAIN SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'test' AND TABLE_NAME = 't1';
+----+-------------+-------+------------+--------+--------------------+------------+---------+-------------------------+------+----------+-------------+
| id | select_type | table | partitions | type   | possible_keys      | key        | key_len | ref                     | rows | filtered | Extra       |
+----+-------------+-------+------------+--------+--------------------+------------+---------+-------------------------+------+----------+-------------+
|  1 | SIMPLE      | cat   | NULL       | index  | PRIMARY            | name       | 194     | NULL                    |    1 |   100.00 | Using index |
|  1 | SIMPLE      | sch   | NULL       | eq_ref | PRIMARY,catalog_id | catalog_id | 202     | mysql.cat.id,const      |    1 |   100.00 | Using index |
|  1 | SIMPLE      | tbl   | NULL       | eq_ref | schema_id          | schema_id  | 202     | mysql.sch.id,const      |    1 |   100.00 | Using where |
|  1 | SIMPLE      | stat  | NULL       | const  | PRIMARY            | PRIMARY    | 388     | const,const             |    1 |   100.00 | Using index |
|  1 | SIMPLE      | ts    | NULL       | eq_ref | PRIMARY            | PRIMARY    | 8       | mysql.tbl.tablespace_id |    1 |   100.00 | Using index |
|  1 | SIMPLE      | col   | NULL       | eq_ref | PRIMARY            | PRIMARY    | 8       | mysql.tbl.collation_id  |    1 |   100.00 | Using index |
+----+-------------+-------+------------+--------+--------------------+------------+---------+-------------------------+------+----------+-------------+
6 rows in set, 1 warning (0.00 sec)

create table t1(c1 int) engine=InnoDB;
create table t2(c1 int) engine=MyISAM;

ll test/
-rw-r----- 1 root root 114688 2月  22 17:47 t1.ibd
-rw-r----- 1 root root   1495 2月  22 17:47 t2_337.sdi
-rw-r----- 1 root root      0 2月  22 17:47 t2.MYD
-rw-r----- 1 root root   1024 2月  22 17:47 t2.MYI

select id from mysql.tables where name='t2';
+-----+
| id  |
+-----+
| 337 |
+-----+

{
    "mysqld_version_id": 80015,
    "dd_version": 80014,
    "sdi_version": 1,
    "dd_object_type": "Table",
    "dd_object": {
        "name": "t2",
        "mysql_version_id": 80015,
        "created": 20190222094723,
        "last_altered": 20190222094723,
        "hidden": 1,
        "options": "avg_row_length=0;key_block_size=0;keys_disabled=0;pack_record=0;stats_auto_recalc=0;stats_sample_pages=0;",
        "columns": [{
            "name": "c1",
            "type": 4,
            "is_nullable": true,
            "is_zerofill": false,
            "is_unsigned": false,
            "is_auto_increment": false,
            "is_virtual": false,
            "hidden": 1,
            "ordinal_position": 1,
            "char_length": 11,
            "numeric_precision": 10,
            "numeric_scale": 0,
            "numeric_scale_null": false,
            "datetime_precision": 0,
            "datetime_precision_null": 1,
            "has_no_default": false,
            "default_value_null": true,
            "srs_id_null": true,
            "srs_id": 0,
            "default_value": "",
            "default_value_utf8_null": true,
            "default_value_utf8": "",
            "default_option": "",
            "update_option": "",
            "comment": "",
            "generation_expression": "",
            "generation_expression_utf8": "",
            "options": "interval_count=0;",
            "se_private_data": "",
            "column_key": 1,
            "column_type_utf8": "int(11)",
            "elements": [],
            "collation_id": 255,
            "is_explicit_collation": false
        }],
        "schema_ref": "test",
        "se_private_id": 18446744073709551615,
        "engine": "MyISAM",
        "last_checked_for_upgrade_version_id": 0,
        "comment": "",
        "se_private_data": "",
        "row_format": 1,
        "partition_type": 0,
        "partition_expression": "",
        "partition_expression_utf8": "",
        "default_partitioning": 0,
        "subpartition_type": 0,
        "subpartition_expression": "",
        "subpartition_expression_utf8": "",
        "default_subpartitioning": 0,
        "indexes": [],
        "foreign_keys": [],
        "partitions": [],
        "collation_id": 255
    }
}

["ibd2sdi"
,
{
    "type": 1,
    "id": 336,
    "object":
        {
    "mysqld_version_id": 80015,
    "dd_version": 80014,
    "sdi_version": 1,
    "dd_object_type": "Table",
    "dd_object": {
        "name": "t1",
        "mysql_version_id": 80015,
        "created": 20190222094723,
        "last_altered": 20190222094723,
        "hidden": 1,
        "options": "avg_row_length=0;key_block_size=0;keys_disabled=0;pack_record=0;stats_auto_recalc=0;stats_sample_pages=0;",
        "columns": [
            {
                "name": "c1",
                "type": 4,
                "is_nullable": true,
                "is_zerofill": false,
                "is_unsigned": false,
                "is_auto_increment": false,
                "is_virtual": false,
                "hidden": 1,
                "ordinal_position": 1,
                "char_length": 11,
                "numeric_precision": 10,
                "numeric_scale": 0,
                "numeric_scale_null": false,
                "datetime_precision": 0,
                "datetime_precision_null": 1,
                "has_no_default": false,
                "default_value_null": true,
                "srs_id_null": true,
                "srs_id": 0,
                "default_value": "",
                "default_value_utf8_null": true,
                "default_value_utf8": "",
                "default_option": "",
                "update_option": "",
                "comment": "",
                "generation_expression": "",
                "generation_expression_utf8": "",
                "options": "interval_count=0;",
                "se_private_data": "table_id=1059;",
                "column_key": 1,
                "column_type_utf8": "int(11)",
                "elements": [],
                "collation_id": 255,
                "is_explicit_collation": false
            },
            {
                "name": "DB_ROW_ID",
                "type": 10,
                "is_nullable": false,
                "is_zerofill": false,
                "is_unsigned": false,
                "is_auto_increment": false,
                "is_virtual": false,
                "hidden": 2,
                "ordinal_position": 2,
                "char_length": 6,
                "numeric_precision": 0,
                "numeric_scale": 0,
                "numeric_scale_null": true,
                "datetime_precision": 0,
                "datetime_precision_null": 1,
                "has_no_default": false,
                "default_value_null": true,
                "srs_id_null": true,
                "srs_id": 0,
                "default_value": "",
                "default_value_utf8_null": true,
                "default_value_utf8": "",
                "default_option": "",
                "update_option": "",
                "comment": "",
                "generation_expression": "",
                "generation_expression_utf8": "",
                "options": "",
                "se_private_data": "table_id=1059;",
                "column_key": 1,
                "column_type_utf8": "",
                "elements": [],
                "collation_id": 63,
                "is_explicit_collation": false
            },
            {
                "name": "DB_TRX_ID",
                "type": 10,
                "is_nullable": false,
                "is_zerofill": false,
                "is_unsigned": false,
                "is_auto_increment": false,
                "is_virtual": false,
                "hidden": 2,
                "ordinal_position": 3,
                "char_length": 6,
                "numeric_precision": 0,
                "numeric_scale": 0,
                "numeric_scale_null": true,
                "datetime_precision": 0,
                "datetime_precision_null": 1,
                "has_no_default": false,
                "default_value_null": true,
                "srs_id_null": true,
                "srs_id": 0,
                "default_value": "",
                "default_value_utf8_null": true,
                "default_value_utf8": "",
                "default_option": "",
                "update_option": "",
                "comment": "",
                "generation_expression": "",
                "generation_expression_utf8": "",
                "options": "",
                "se_private_data": "table_id=1059;",
                "column_key": 1,
                "column_type_utf8": "",
                "elements": [],
                "collation_id": 63,
                "is_explicit_collation": false
            },
            {
                "name": "DB_ROLL_PTR",
                "type": 9,
                "is_nullable": false,
                "is_zerofill": false,
                "is_unsigned": false,
                "is_auto_increment": false,
                "is_virtual": false,
                "hidden": 2,
                "ordinal_position": 4,
                "char_length": 7,
                "numeric_precision": 0,
                "numeric_scale": 0,
                "numeric_scale_null": true,
                "datetime_precision": 0,
                "datetime_precision_null": 1,
                "has_no_default": false,
                "default_value_null": true,
                "srs_id_null": true,
                "srs_id": 0,
                "default_value": "",
                "default_value_utf8_null": true,
                "default_value_utf8": "",
                "default_option": "",
                "update_option": "",
                "comment": "",
                "generation_expression": "",
                "generation_expression_utf8": "",
                "options": "",
                "se_private_data": "table_id=1059;",
                "column_key": 1,
                "column_type_utf8": "",
                "elements": [],
                "collation_id": 63,
                "is_explicit_collation": false
            }
        ],
        "schema_ref": "test",
        "se_private_id": 1059,
        "engine": "InnoDB",
        "last_checked_for_upgrade_version_id": 0,
        "comment": "",
        "se_private_data": "",
        "row_format": 2,
        "partition_type": 0,
        "partition_expression": "",
        "partition_expression_utf8": "",
        "default_partitioning": 0,
        "subpartition_type": 0,
        "subpartition_expression": "",
        "subpartition_expression_utf8": "",
        "default_subpartitioning": 0,
        "indexes": [
            {
                "name": "PRIMARY",
                "hidden": true,
                "is_generated": false,
                "ordinal_position": 1,
                "comment": "",
                "options": "",
                "se_private_data": "id=140;root=4;space_id=2;table_id=1059;trx_id=2569;",
                "type": 2,
                "algorithm": 2,
                "is_algorithm_explicit": false,
                "is_visible": true,
                "engine": "InnoDB",
                "elements": [
                    {
                        "ordinal_position": 1,
                        "length": 4294967295,
                        "order": 2,
                        "column_opx": 1
                    },
                    {
                        "ordinal_position": 2,
                        "length": 4294967295,
                        "order": 2,
                        "column_opx": 2
                    },
                    {
                        "ordinal_position": 3,
                        "length": 4294967295,
                        "order": 2,
                        "column_opx": 3
                    },
                    {
                        "ordinal_position": 4,
                        "length": 4294967295,
                        "order": 2,
                        "column_opx": 0
                    }
                ],
                "tablespace_ref": "test/t1"
            }
        ],
        "foreign_keys": [],
        "partitions": [],
        "collation_id": 255
    }
}
}
,
{
    "type": 2,
    "id": 7,
    "object":
        {
    "mysqld_version_id": 80015,
    "dd_version": 80014,
    "sdi_version": 1,
    "dd_object_type": "Tablespace",
    "dd_object": {
        "name": "test/t1",
        "comment": "",
        "options": "",
        "se_private_data": "flags=16417;id=2;server_version=80015;space_version=1;state=normal;",
        "engine": "InnoDB",
        "files": [
            {
                "ordinal_position": 1,
                "filename": "./test/t1.ibd",
                "se_private_data": "id=2;"
            }
        ]
    }
}
}
]

create table SDI_$TABLESPACEID(type int,
                               id int,
                               compressed_len int,
                               uncompressed_len int,
                               data blob not null,
                               primary key(type,id));

dd::sdi::store
     -->dd::sdi_tablespace::store_tsp_sdi // store tablespace SDI
          -->dict_sdi_set
               -->ib_sdi_set
                    -->ib_cursor_insert_row
    -->dd::sdi_tablespace::store_tbl_sdi // store table SDI
          -->ib_sdi_set
               -->ib_sdi_set
                    -->ib_cursor_insert_row

class Storage_adapter {

 /**
   Drop a dictionary object from persistent storage.
 */

 template <typename T>
 static bool drop(THD *thd, const T *object);

/**
  Store a dictionary object to persistent storage.
*/

template <typename T>
static bool store(THD *thd, T *object);
}

mysql_create_table
    -->mysql_create_table_no_lock
          -->create_table_impl
               -->rea_create_base_table
                    -->dd::cache::Dictionary_client::store<dd::Table> // mysql.tables
                         -->dd::cache::Storage_adapter::store<dd::Table>
                              -->dd::Weak_object_impl::store
                                   -->dd::Raw_new_record::insert // store mysql.tables
                                         -->handler::ha_write_row
                                              -->ha_innobase::write_row
                                  -->dd::Table_impl::store_children
                                       -->dd::Abstract_table_impl::store_children // store  mysql.columns
                                            -->dd::Collection<dd::Column*>::store_items
                                       -->dd::Collection<dd::Index*>::store_items // store mysql.indexes
                                            -->dd::Weak_object_impl::store
                                                  -->dd::Index_impl::store_children
                                                       -->dd::Collection<dd::Index_element*>::store_items // store mysql.index_column_usage
                              -->dd::sdi::store //store table SDI
                    -->ha_create_table
                         -->handler::ha_create
                               -->ha_innobase::create
                                    -->innobase_basic_ddl::create_impl
                                         -->create_table_info_t::create_table_update_global_dd
                                              -->dd_set_autoinck
                                              -->dd_create_implicit_tablespace
                                                   -->dd_create_tablespace
                                                        -->dd::cache::Dictionary_client::store<dd::Tablespace>
                                                             -->dd::cache::Storage_adapter::store<dd::Tablespace>
                                                                   -->dd::Weak_object_impl::store // store mysql.tablespace
                                                                       -->dd::Tablespace_impl::store_children
                                                                            -->dd::Collection<dd::Tablespace_file*>::store_items
                                                                                -->dd::Tablespace_file_impl::store // store tablespace_files
                                                                   -->dd::sdi::store     // store tablespace SDI
                         -->dd::cache::Dictionary_client::update<dd::Table> // 更新innodb引擎相关元数据
                              -->dd::cache::Storage_adapter::store<dd::Table>
                              -->dd::Weak_object_impl::store

create table t1(c1 int primary key, c2 int) engine=innodb;

select s.name as schema_name, t.* from mysql.tables t, mysql.schemata s where s.id=t.schema_id and s.name='test' and t.name='t1'\G
*************************** 1. row ***************************
                        schema_name: test
                                 id: 374
                          schema_id: 5
                               name: t1
                               type: BASE TABLE
                             engine: InnoDB
                   mysql_version_id: 80015
                         row_format: Dynamic
                       collation_id: 255
                            comment:
                             hidden: Visible
                            options: avg_row_length=0;key_block_size=0;keys_disabled=0;pack_record=0;stats_auto_recalc=0;stats_sample_pages=0;
                    se_private_data: NULL
                      se_private_id: 1096
                      tablespace_id: NULL
                     partition_type: NULL
               partition_expression: NULL
          partition_expression_utf8: NULL
               default_partitioning: NULL
                  subpartition_type: NULL
            subpartition_expression: NULL
       subpartition_expression_utf8: NULL
            default_subpartitioning: NULL
                            created: 2019-03-12 19:30:46
                       last_altered: 2019-03-12 19:30:46
                    view_definition: NULL
               view_definition_utf8: NULL
                  view_check_option: NULL
                  view_is_updatable: NULL
                     view_algorithm: NULL
                 view_security_type: NULL
                       view_definer: NULL
           view_client_collation_id: NULL
       view_connection_collation_id: NULL
                  view_column_names: NULL
last_checked_for_upgrade_version_id: 0

select * from mysql.indexes where table_id= 374\G
*************************** 1. row ***************************
                   id: 299
             table_id: 374
                 name: PRIMARY
                 type: PRIMARY
            algorithm: BTREE
is_algorithm_explicit: 0
           is_visible: 1
         is_generated: 0
               hidden: 0
     ordinal_position: 1
              comment:
              options: flags=0;
      se_private_data: id=177;root=4;space_id=39;table_id=1096;trx_id=9996;
        tablespace_id: 43
               engine: InnoDB

select id, name, type from mysql.columns where table_id= 374;
+------+-------------+---------------------+
| id   | name        | type                |
+------+-------------+---------------------+
| 4025 | c1          | MYSQL_TYPE_LONG     |
| 4026 | c2          | MYSQL_TYPE_LONG     |
| 4028 | DB_ROLL_PTR | MYSQL_TYPE_LONGLONG |
| 4027 | DB_TRX_ID   | MYSQL_TYPE_INT24    |
+------+-------------+---------------------+

select * from mysql.index_column_usage where index_id=299;
+----------+------------------+-----------+--------+-------+--------+
| index_id | ordinal_position | column_id | length | order | hidden |
+----------+------------------+-----------+--------+-------+--------+
|      299 |                1 |      4025 |      4 | ASC   |      0 |
|      299 |                2 |      4027 |   NULL | ASC   |      1 |
|      299 |                3 |      4028 |   NULL | ASC   |      1 |
|      299 |                4 |      4026 |   NULL | ASC   |      1 |
+----------+------------------+-----------+--------+-------+--------+

select * from mysql.tablespaces where name='test/t1';
+----+---------+---------+----------------------------------------------------------------------+---------+--------+
| id | name    | options | se_private_data                                                      | comment | engine |
+----+---------+---------+----------------------------------------------------------------------+---------+--------+
| 43 | test/t1 | NULL    | flags=16417;id=39;server_version=80015;space_version=1;state=normal; |         | InnoDB |
+----+---------+---------+----------------------------------------------------------------------+---------+--------+

select * from mysql.tablespace_files where tablespace_id=43;
+---------------+------------------+---------------+-----------------+
| tablespace_id | ordinal_position | file_name     | se_private_data |
+---------------+------------------+---------------+-----------------+
|            43 |                1 | ./test/t1.ibd | id=39;          |
+---------------+------------------+---------------+-----------------+

select * from mysql.tablespaces a, mysql.tablespace_files b where a.id=b.tablespace_id and a.name='test/t1';
+----+---------+---------+----------------------------------------------------------------------+---------+--------+---------------+------------------+---------------+-----------------+
| id | name    | options | se_private_data                                                      | comment | engine | tablespace_id | ordinal_position | file_name     | se_private_data |
+----+---------+---------+----------------------------------------------------------------------+---------+--------+---------------+------------------+---------------+-----------------+
| 43 | test/t1 | NULL    | flags=16417;id=39;server_version=80015;space_version=1;state=normal; |         | InnoDB |            43 |                1 | ./test/t1.ibd | id=39;          |
+----+---------+---------+------------------------------------------------------

dd::Dictionary_impl::init
     -->bootstrap::initialize
            -->DDSE_dict_init
                 -->innobase_ddse_dict_init
                      -->innobase_init_files //创建mysql.ibd
            -->initialize_dictionary
                 -->create_dd_schema/initialize_dd_properties/create_tables
                 -->DDSE_dict_recover // 创建mysql/innodb_system tablespace
                 -->flush_meta_data
                      -->dd::cache::Storage_adapter::store()   //
                           -->dd::Weak_object_impl::store
                                -->dd::Table_impl::store_attributes
                      -->dd::cache::Storage_adapter::core_store  // 存储到Object_registry m_core_registry;
                      -->dd::sdi::store
                 -->populate_tables
                      -->get_dml
                 -->update_properties
                 -->update_versions

enum class Log_Type : uint32_t {
/** Smallest log type */
SMALLEST_LOG = 1,

/** Drop an index tree */
FREE_TREE_LOG = 1,

/** Delete a file */
DELETE_SPACE_LOG,

/** Rename a file */
RENAME_SPACE_LOG,

/** Drop the entry in innodb_dynamic_metadata */
DROP_LOG,

/** Rename table in dict cache. */
RENAME_TABLE_LOG,

/** Remove a table from dict cache */
REMOVE_CACHE_LOG,

/** Alter Encrypt a tablespace */
ALTER_ENCRYPT_TABLESPACE_LOG,

/** Biggest log type */
BIGGEST_LOG = ALTER_ENCRYPT_TABLESPACE_LOG
};

mysql.innodb_ddl_log 表结构如下：

CREATE TABLE `innodb_ddl_log` (
`id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`thread_id` bigint(20) unsigned NOT NULL,
`type` int(10) unsigned NOT NULL,
`space_id` int(10) unsigned DEFAULT NULL,
`page_no` int(10) unsigned DEFAULT NULL,
`index_id` bigint(20) unsigned DEFAULT NULL,
`table_id` bigint(20) unsigned DEFAULT NULL,
`old_file_path` varchar(512) CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL,
`new_file_path` varchar(512) CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `thread_id` (`thread_id`);

Prepare: Create the required objects and write the DDL logs to the mysql.innodb_ddl_log table. The DDL logs define how to roll forward and roll back the DDL operation.

Perform: Perform the DDL operation. For example, perform a create routine for a CREATE TABLE operation.

Commit: Update the data dictionary and commit the data dictionary transaction.

Post-DDL: Replay and remove DDL logs from the mysql.innodb_ddl_log table. To ensure that rollback can be performed safely without introducing inconsistencies, file operations such as renaming or removing data files are performed in this final phase. This phase also removes dynamic metadata from the mysql.innodb_dynamic_metadata data dictionary table for DROP TABLE, TRUNCATE TABLE, and other DDL operations that rebuild the table.

mysql_rm_table
     -->mysql_rm_table_no_locks
        -->drop_base_table
            -->ha_delete_table
               -—>handler::ha_delete_table
                  -->ha_innobase::delete_table
                    -->innobase_basic_ddl::delete_impl
                       -->row_drop_table_for_mysql
                          -->Log_DDL::write_drop_log               // 记录删innodb_dynamic_metadata日志
                          -—>Log_DDL::write_delete_space_log       // 记录删ibd日志
            -->dd::drop_table
                -->dd::cache::Dictionary_client::drop<dd::Table>
                    -->dd::cache::Storage_adapter::drop<dd::Table>
                         -->dd::sdi::drop
        -->innobase_post_ddl
            -->Log_DDL::post_ddl
               -->Log_DDL::replay_by_thread_id
                    -->Log_DDL::replay
                       —>Log_DDL::replay_delete_space_log // post-ddl 真正删除innodb_dynamic_metadata
                       —>Log_DDL::replay_drop_log         // post-ddl 真正删除ibd
                    -->delete_by_ids
                       -->DDL_Log_Table::remove

create_table
        -->Log_DDL::write_delete_space_log
        -->Log_DDL::write_remove_cache_log
        -->Log_DDL::write_free_tree_log

init_server_components
    -->ha_post_recover
         -->post_recover_handlerton
              -->innobase_post_recover
                   -->Log_DDL::recover
                        -->Log_DDL::replay_all
                             -->Log_DDL::replay
                                  -->replay_delete_space_log/replay_remove_cache_log/replay_free_tree_log
                        -->delete_by_ids
                             -->DDL_Log_Table::remove

Sql_cmd_truncate_table::truncate_table
    -->ha_create_table
         -->handler::ha_create
              -->ha_innobase::create
                   -->ha_innobase::truncate_impl
                        -->innobase_truncate<dd::Table>::exec
                             -->innobase_truncate<Table>::truncate
                                  -->rename_tablespace . // t1.ibd rename to #sql-ib1084-513656514.ibd
                                       -->fil_rename_tablespace
                                            -->Fil_shard::space_rename
                                                 -->Log_DDL::write_rename_space_log
                                  -->innobase_basic_ddl::delete_impl
                                       -->row_drop_table_for_mysql
                                            -->Log_DDL::write_delete_space_log// drop #sql-ib1084-513656514.ibd
                                  -->innobase_basic_ddl::create_impl
                                       -->create_table_info_t::create_table
                                            -->create_table_info_t::create_table_def
                                                 -->row_create_table_for_mysql
                                                      -->dict_build_table_def
                                                           -->dict_build_tablespace_for_table
                                                                -->Log_DDL::write_delete_space_log // drop t1.ibd
                                                       -->Log_DDL::write_remove_cache_log
                                                       -->dict_create_index_tree_in_mem
                                                            -->Log_DDL::write_free_tree_log
      -->innobase_post_ddl
           -->Log_DDL::post_ddl
                -->Log_DDL::replay_by_thread_id
                      -->Log_DDL::replay
                          -->Log_DDL::replay_delete_space_log // drop #sql-ib1084-513656514.ibd
                          --> Log_DDL::replay_drop_log
                -->delete_by_ids
                      -->DDL_Log_Table::remove

mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| t1             |
+----------------+

mysql> drop table t1,tt;
ERROR 1051 (42S02): Unknown table 'test.tt'
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| t1             |
+----------------+

show binlog events;
+------------------+-----+----------------+-----------+-------------+-----------------------------------------+
| Log_name         | Pos | Event_type     | Server_id | End_log_pos | Info                                    |
+------------------+-----+----------------+-----------+-------------+-----------------------------------------+
| mysql-bin.000001 |   4 | Format_desc    |         1 |         124 | Server ver: 8.0.15-debug, Binlog ver: 4 |
| mysql-bin.000001 | 124 | Previous_gtids |         1 |         155 |                                         |
+------------------+-----+----------------+-----------+-------------+-----------------------------------------+
2 rows in set (0.00 sec)

MLOG_TABLE_DYNAMIC_META
id,
version,
PM_TABLE_AUTO_INC,
autoinc

log_checkpointer
     -->log_consider_checkpoint
         -->dict_persist_to_dd_table_buffer
              -->dict_table_persist_to_dd_table_buffer_low
                   -->Persisters::write
                        -->AutoIncPersister::write
                        -->DDTableBuffer::replace

dict_table_remove_from_cache_low
    -->dict_table_persist_to_dd_table_buffer_low
        -->Persisters::write
            -->AutoIncPersister::write
            -->DDTableBuffer::replace