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This article introduces the relevant knowledge of "MySQL's handling of DROP TABLE". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

A few days ago, during DROP TABLE, all processes, whether DDL or DML, were started by HANG; execution did not continue until the end of DROP.

I am very confused about this phenomenon.

Today, I studied a MYSQL source code to see its internal processing of DROP TABLE.

When the user issues the DROP TABLE command:

# MYSQL SERVER handles deleting a table #

/ * Sql_table.cc delete (drop) tables. , /

Bool mysql_rm_table ()

/ * Execute the drop of a normal or temporary table * /

Int mysql_rm_table_part2 ()

/ * Remove matching tables from the HANDLER's hash table. , /

Void mysql_ha_rm_tables ()

/ * Mark all entries with the table as deleted to force an reopen of the table * /

Remove_table_from_cache ()

/ * remove engine files * / LINE 2024

Int handler::ha_delete_table (const char * name)

File- > ha_delete_table (path) line 1991

Int handler::delete_table (const char * name) / / Delete the physical table file

/ * here INNODB inherits the parent class handler

What is actually called is this int ha_innobase::delete_table

Go to the following: # INNODB handles deleting a table #

If it is another engine, delete the data file directly and go down * /

Int mysys::my_delete_with_symlink (const char * name, myf MyFlags)

Int mysys::my_delete (const char * name, myf MyFlags)

/ * Delete the table definition file * / LINE 2042

Int mysys::my_delete ()

/ * clear query cache*/

Query_cache_invalidate3

/ * writes to BINLOG * /

# INNODB handles deleting a table #

/ * Drops a table from an InnoDB database. , /

Int ha_innobase::delete_table (const char* name); / / Delete the table from INNODB

Int row_drop_table_for_mysql ()

/ * Foreign key association check * /

/ * Lock the data dictionary (exclusive lock) * /

/ * Serialize data dictionary operations with dictionary mutex:

Row_mysql_lock_data_dictionary (trx)

/ * Update Digital Dictionary (MEMDB,information_schema), line 3178 * /

Que_eval_sql (info, "PROCEDURE DROP_TABLE_PROC () IS\ n"

/ * this is handled through a PROCEDURE * /

/ * Update Digital Dictionary (CACHE) * /

Void dict_table_remove_from_cache (dict_table_t* table))

/ * Delete the data file

/ * Deletes a single-table tablespace * /

Ibool fil_delete_tablespace ()

/ * Frees a space object from the tablespace memory cache*/

Ibool fil_space_free ()

/ * Deletes a file. The file has to be closed before calling this. , /

Ibool os_file_delete ()

Unlink ((const char*) name)

/ * release the lock * /

Row_mysql_unlock_data_dictionary (trx)

DROP TABLE is probably such a process.

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