From 2e0687e12d117e4388b46dc13c411362c179c27e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marko=20M=C3=A4kel=C3=A4?= Date: Fri, 15 Dec 2017 19:10:36 +0200 Subject: [PATCH 6/6] WIP (dead end) defer DROP TABLE to COMMIT This cannot work. Instead, we must stop using multiple transactions per DDL operation, and we must split the dict_operation_lock into MDL, so that multiple DDL operations may concurrently update the InnoDB data dictionary tables. --- storage/innobase/fil/fil0fil.cc | 2 +- storage/innobase/handler/ha_innodb.cc | 65 ++++++++++++++++++----------------- storage/innobase/include/fil0fil.h | 2 +- storage/innobase/include/trx0trx.h | 9 ++++- storage/innobase/trx/trx0trx.cc | 19 ++++++++++ 5 files changed, 62 insertions(+), 35 deletions(-) diff --git a/storage/innobase/fil/fil0fil.cc b/storage/innobase/fil/fil0fil.cc index 8c86e272853..1bbf97571c4 100644 --- a/storage/innobase/fil/fil0fil.cc +++ b/storage/innobase/fil/fil0fil.cc @@ -6152,7 +6152,7 @@ fil_mtr_rename_log( !is_system_tablespace(old_table->space); bool new_is_file_per_table = - !is_system_tablespace(new_table->space); + new_table && !is_system_tablespace(new_table->space); /* If neither table is file-per-table, there will be no renaming of files. */ diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc index 3f08f84a4cd..f277e97f54b 100644 --- a/storage/innobase/handler/ha_innodb.cc +++ b/storage/innobase/handler/ha_innodb.cc @@ -13339,15 +13339,6 @@ ha_innobase::delete_table( dberr_t err; THD* thd = ha_thd(); int sql_command = thd_sql_command(thd); - - if (sql_command == SQLCOM_CREATE_TABLE) { - /* On an error, CREATE TABLE...SELECT may invoke - the DROP TABLE functionality. Let us ignore this, - and instead let the transaction rollback - drop the table. */ - return 0; - } - char norm_name[FN_REFLEN]; DBUG_ENTER("ha_innobase::delete_table"); @@ -13374,26 +13365,6 @@ ha_innobase::delete_table( TrxInInnoDB trx_in_innodb(parent_trx); - /* Remove the to-be-dropped table from the list of modified tables - by parent_trx. Otherwise we may end up with an orphaned pointer to - the table object from parent_trx::mod_tables. This could happen in: - SET AUTOCOMMIT=0; - CREATE TABLE t (PRIMARY KEY (a)) ENGINE=INNODB SELECT 1 AS a UNION - ALL SELECT 1 AS a; */ - trx_mod_tables_t::const_iterator iter; - - for (iter = parent_trx->mod_tables.begin(); - iter != parent_trx->mod_tables.end(); - ++iter) { - - dict_table_t* table_to_drop = iter->first; - - if (strcmp(norm_name, table_to_drop->name.m_name) == 0) { - parent_trx->mod_tables.erase(table_to_drop); - break; - } - } - trx_t* trx = innobase_trx_allocate(thd); ulint name_len = strlen(name); @@ -13408,6 +13379,32 @@ ha_innobase::delete_table( /* We are doing a DDL operation. */ ++trx->will_lock; + /* Defer the dropping of the table to parent_trx if it is + locked there, and only rename the table to a temporary name + here. This is needed in the following: + CREATE TABLE t (PRIMARY KEY(a)) ENGINE=INNODB + SELECT 1 a UNION SELECT 1 a; */ + + for (trx_mod_tables_t::iterator i = parent_trx->mod_tables.begin(); + i != parent_trx->mod_tables.end(); ++i) { + const char* name = i->first->name.m_name; + if (!strcmp(norm_name, name)) { + ut_ad(sql_command == SQLCOM_CREATE_TABLE); + i->second.drop(); + mem_heap_t* heap = mem_heap_create(FN_REFLEN); + trx_set_dict_operation(trx, TRX_DICT_OP_INDEX); + trx_start_if_not_started(trx, true); + row_mysql_lock_data_dictionary(trx); + err = row_rename_table_for_mysql( + name, + dict_mem_create_temporary_tablename( + heap, name, i->first->id), + trx, false); + mem_heap_free(heap); + goto func_exit; + } + } + /* Drop the table in InnoDB */ err = row_drop_table_for_mysql( @@ -13507,15 +13504,19 @@ ha_innobase::delete_table( } } - ut_ad(!srv_read_only_mode); +func_exit: + innobase_commit_low(trx); + + if (trx->dict_operation_lock_mode) { + row_mysql_unlock_data_dictionary(trx); + } + /* Flush the log to reduce probability that the .frm files and the InnoDB data dictionary get out-of-sync if the user runs with innodb_flush_log_at_trx_commit = 0 */ log_buffer_flush_to_disk(); - innobase_commit_low(trx); - trx_free_for_mysql(trx); DBUG_RETURN(convert_error_code_to_mysql(err, 0, NULL)); diff --git a/storage/innobase/include/fil0fil.h b/storage/innobase/include/fil0fil.h index febf47c1d08..c6e1c76904e 100644 --- a/storage/innobase/include/fil0fil.h +++ b/storage/innobase/include/fil0fil.h @@ -1516,7 +1516,7 @@ fil_mtr_rename_log( const dict_table_t* new_table, const char* tmp_name, mtr_t* mtr) - MY_ATTRIBUTE((nonnull, warn_unused_result)); + MY_ATTRIBUTE((nonnull(1,3,4), warn_unused_result)); /** Acquire the fil_system mutex. */ #define fil_system_enter() mutex_enter(&fil_system->mutex) diff --git a/storage/innobase/include/trx0trx.h b/storage/innobase/include/trx0trx.h index 6e6ad11c265..3fdff93a1bd 100644 --- a/storage/innobase/include/trx0trx.h +++ b/storage/innobase/include/trx0trx.h @@ -782,6 +782,8 @@ struct trx_lock_t { /** Logical first modification time of a table in a transaction */ class trx_mod_table_time_t { + /** Whether the table is to be dropped at transaction commit */ + bool drop_table; /** First modification of the table */ undo_no_t first; @@ -789,7 +791,12 @@ class trx_mod_table_time_t /** Constructor @param[in] rows number of modified rows so far */ trx_mod_table_time_t(undo_no_t rows) - : first(rows) {} + : drop_table(false), first(rows) {} + + /** Note that the table will be dropped on transaction commit */ + void drop() { drop_table= true; } + /** @return whether the table shall be dropped on commit */ + bool must_drop() const { return drop_table; } /** Invoked after partial rollback @param[in] limit number of surviving modified rows diff --git a/storage/innobase/trx/trx0trx.cc b/storage/innobase/trx/trx0trx.cc index 986eb760cef..1a6d40e884b 100644 --- a/storage/innobase/trx/trx0trx.cc +++ b/storage/innobase/trx/trx0trx.cc @@ -1628,6 +1628,23 @@ trx_update_mod_tables_timestamp( trx->mod_tables.clear(); } +/* If there was any deferred DROP TABLE operation, modify the InnoDB +data dictionary as the last step before commit or XA PREPARE. */ +static +void +trx_drop_tables_at_commit(trx_t* trx) +{ + const bool dict_locked = !trx->dict_operation_lock_mode; + if (dict_locked) { + row_mysql_lock_data_dictionary(trx); + } + + if (dict_locked) { + row_mysql_unlock_data_dictionary(trx); + } +} + + /** Erase the transaction from running transaction lists and serialization list. Active RW transaction list of a MVCC snapshot(ReadView::prepare) @@ -1921,6 +1938,7 @@ trx_commit_low( bool serialised; if (mtr != NULL) { + trx_drop_tables_at_commit(trx); mtr->set_sync(); @@ -2700,6 +2718,7 @@ trx_prepare( /* Only fresh user transactions can be prepared. Recovered transactions cannot. */ ut_a(!trx->is_recovered); + trx_drop_tables_at_commit(trx); lsn_t lsn = trx_prepare_low(trx); -- 2.15.1