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Code Activity

MDEV-24408 Crash-safe DROP DATABASE

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Description of how DROP DATABASE works after this patch

- Collect list of tables
- DDL log tables as they are dropped
- DDL log drop database
- Delete db.opt
- Delete data directory
- Log either DROP TABLE or DROP DATABASE to binary log
- De active ddl log entry

This is in line of how things where before (minus ddl logging) except that
we delete db.opt file last to not loose it if DROP DATABASE fails.

On recovery we have to ensure that all dropped tables are logged in
binary log and that they are properly dropped (as with atomic drop
table).
No new tables be dropped as part of recovery.

Recovery of active drop database ddl log entry:

- If drop database was logged to ddl log but was not found in the binary
  log:
  - drop the db.opt file and database directory.
  - Log DROP DATABASE to binary log
- If drop database was not logged to ddl log
  - Update binary log with DROP TABLE of the dropped tables. If table list
    is longer than max_allowed_packet, then the query will be split into
    multiple DROP TABLE/VIEW queries.

Other things:
- Added DDL_LOG_STATE and 'current database' as arguments to
  mysql_rm_table_no_locks(). This was needed to be able to combine
  ddl logging of DROP DATABASE and DROP TABLE and make the generated
  DROP TABLE statements shorter.
- To make the DROP TABLE statement created by ddl log shorter, I changed
  the binlogged query to use current directory and omit the directory
  part for all tables in the current directory.
- Merged some DROP TABLE and DROP VIEW code in ddl logger.  This was done
  to be able get separate DROP VIEW and DROP TABLE statements in the binary
  log.
- Added a 'recovery_state' variable to remember the state of dropped
  tables and views.
- Moved out code that drops database objects (stored procedures) from
  mysql_rm_db_internal() to drop_database_objects() for better code reuse.
- Made mysql_rm_db_internal() global so that could be used by the ddl
  recovery code.
This commit is contained in:
Monty
2020-12-20 17:44:11 +02:00
committed by Sergei Golubchik
parent 407e9b78cf
commit 7a588c30b1
18 changed files with 910 additions and 282 deletions
Download Patch File Download Diff File Expand all files Collapse all files

68
sql/sql_table.cc
View File

@@ -1041,7 +1041,9 @@ bool mysql_rm_table(THD *thd,TABLE_LIST *tables, bool if_exists,
/* mark for close and remove all cached entries */
thd->push_internal_handler(&err_handler);
error= mysql_rm_table_no_locks(thd, tables, if_exists, drop_temporary,
error= mysql_rm_table_no_locks(thd, tables, &thd->db, (DDL_LOG_STATE*) 0,
if_exists,
drop_temporary,
false, drop_sequence, dont_log_query,
false);
thd->pop_internal_handler();
@@ -1102,6 +1104,11 @@ static uint32 get_comment(THD *thd, uint32 comment_pos,
@param thd Thread handler
@param tables Tables to drop
@param current_db Current database, used for ddl logs
@param ddl_log_state DDL log state, for global ddl logging (used by
DROP DATABASE. If not set, an internal ddl log state
will be used. If set then the caller must call
ddl_log_complete(ddl_log_state);
@param if_exists If set, don't give an error if table doesn't exists.
In this case we give an warning of level 'NOTE'
@param drop_temporary Only drop temporary tables
@@ -1130,7 +1137,10 @@ static uint32 get_comment(THD *thd, uint32 comment_pos,
not all.
*/
int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables,
const LEX_CSTRING *current_db,
DDL_LOG_STATE *ddl_log_state,
bool if_exists,
bool drop_temporary, bool drop_view,
bool drop_sequence,
bool dont_log_query,
@@ -1140,7 +1150,7 @@ int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
char path[FN_REFLEN + 1];
LEX_CSTRING alias= null_clex_str;
StringBuffer<160> unknown_tables(system_charset_info);
DDL_LOG_STATE ddl_log_state;
DDL_LOG_STATE local_ddl_log_state;
const char *comment_start;
uint not_found_errors= 0, table_count= 0, non_temp_tables_count= 0;
int error= 0;
@@ -1156,6 +1166,12 @@ int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
String built_trans_tmp_query, built_non_trans_tmp_query;
DBUG_ENTER("mysql_rm_table_no_locks");
if (!ddl_log_state)
{
ddl_log_state= &local_ddl_log_state;
bzero(ddl_log_state, sizeof(*ddl_log_state));
}
unknown_tables.length(0);
comment_len= get_comment(thd, if_exists ? 17:9, &comment_start);
@@ -1209,14 +1225,13 @@ int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
built_non_trans_tmp_query.set_charset(system_charset_info);
built_non_trans_tmp_query.copy(built_trans_tmp_query);
}
bzero(&ddl_log_state, sizeof(ddl_log_state));
for (table= tables; table; table= table->next_local)
{
bool is_trans= 0, temporary_table_was_dropped= 0;
bool table_creation_was_logged= 0;
bool wrong_drop_sequence= 0;
bool table_dropped= 0;
bool table_dropped= 0, res;
const LEX_CSTRING db= table->db;
const LEX_CSTRING table_name= table->table_name;
LEX_CSTRING cpath= {0,0};
@@ -1376,7 +1391,7 @@ int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
if (!table_count++)
{
LEX_CSTRING comment= {comment_start, (size_t) comment_len};
if (ddl_log_drop_table_init(thd, &ddl_log_state, &comment))
if (ddl_log_drop_table_init(thd, ddl_log_state, current_db, &comment))
{
error= 1;
goto err;
@@ -1434,12 +1449,18 @@ int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
bool enoent_warning= !dont_log_query && !(hton && hton->discover_table);
if (ddl_log_drop_table(thd, &ddl_log_state, hton, &cpath, &db,
&table_name))
if (was_view)
res= ddl_log_drop_view(thd, ddl_log_state, &cpath, &db,
&table_name);
else
res= ddl_log_drop_table(thd, ddl_log_state, hton, &cpath, &db,
&table_name);
if (res)
{
error= -1;
goto err;
error= -1;
goto err;
}
debug_crash_here("ddl_log_drop_before_delete_table");
error= ha_delete_table(thd, hton, path, &db, &table_name,
enoent_warning);
@@ -1510,7 +1531,7 @@ int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
int ferror= 0;
DBUG_ASSERT(!was_view);
if (ddl_log_drop_table(thd, &ddl_log_state, hton, &cpath, &db,
if (ddl_log_drop_table(thd, ddl_log_state, 0, &cpath, &db,
&table_name))
{
error= -1;
@@ -1548,9 +1569,12 @@ int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
if (thd->replication_flags & OPTION_IF_EXISTS)
log_if_exists= 1;
debug_crash_here("ddl_log_drop_before_drop_trigger");
ddl_log_update_phase(&ddl_log_state, DDL_DROP_PHASE_TRIGGER);
debug_crash_here("ddl_log_drop_before_drop_trigger2");
if (!was_view)
{
debug_crash_here("ddl_log_drop_before_drop_trigger");
ddl_log_update_phase(ddl_log_state, DDL_DROP_PHASE_TRIGGER);
debug_crash_here("ddl_log_drop_before_drop_trigger2");
}
if (likely(!error) || non_existing_table_error(error))
{
@@ -1610,7 +1634,8 @@ report_error:
table_name.str, (uint)table_name.length);
mysql_audit_drop_table(thd, table);
}
ddl_log_update_phase(&ddl_log_state, DDL_DROP_PHASE_BINLOG);
if (!was_view)
ddl_log_update_phase(ddl_log_state, DDL_DROP_PHASE_BINLOG);
if (!dont_log_query &&
(!error || table_dropped || non_existing_table_error(error)))
@@ -1715,7 +1740,7 @@ err:
built_query.append(normal_tables.ptr(), normal_tables.length());
built_query.append(generated_by_server);
thd->binlog_xid= thd->query_id;
ddl_log_update_xid(&ddl_log_state, thd->binlog_xid);
ddl_log_update_xid(ddl_log_state, thd->binlog_xid);
error |= (thd->binlog_query(THD::STMT_QUERY_TYPE,
built_query.ptr(),
built_query.length(),
@@ -1725,7 +1750,8 @@ err:
debug_crash_here("ddl_log_drop_after_binlog");
}
}
ddl_log_complete(&ddl_log_state);
if (ddl_log_state == &local_ddl_log_state)
ddl_log_complete(ddl_log_state);
if (!drop_temporary)
{
@@ -4234,7 +4260,9 @@ int create_table_impl(THD *thd, const LEX_CSTRING &orig_db,
*/
(void) trans_rollback_stmt(thd);
/* Remove normal table without logging. Keep tables locked */
if (mysql_rm_table_no_locks(thd, &table_list, 0, 0, 0, 0, 1, 1))
if (mysql_rm_table_no_locks(thd, &table_list, &thd->db,
(DDL_LOG_STATE*) 0,
0, 0, 0, 0, 1, 1))
goto err;
/*
@@ -4453,7 +4481,9 @@ int mysql_create_table_no_lock(THD *thd, const LEX_CSTRING *db,
{
DBUG_ASSERT(thd->is_error());
/* Drop the table as it wasn't completely done */
if (!mysql_rm_table_no_locks(thd, table_list, 1,
if (!mysql_rm_table_no_locks(thd, table_list, &thd->db,
(DDL_LOG_STATE*) 0,
1,
create_info->tmp_table(),
false, true /* Sequence*/,
true /* Don't log_query */,