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MDEV-24395 Atomic DROP TRIGGER

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The purpose of this task is to ensure that DROP TRIGGER is atomic.

Description of how atomic drop trigger works:

Logging of DROP TRIGGER
    Log the following information:
    db
    table name
    trigger name
    xid /* Used to check if query was already logged to binary log */
    initial length of the .TRG file
    query if there is space for it, if not log a zero length query.

Recovery operations:
- Delete if exists 'database/trigger_name.TRN~'
  - If this file existed, it means that we crashed before the trigger
    was deleted and there is nothing else to do.
- Get length of .TRG file
  - If file length is unchanged, trigger was not dropped. Nothing else to
    do.
- Log original query to binary, if it was stored in the ddl log. If it was
  not stored (long query string), log the following query to binary log:
  use `database` ; DROP TRIGGER IF EXISTS `trigger_name`
  /* generated by ddl log */;

Other things:
- Added trigger name and DDL_LOG_STATE to drop_trigger()
  Trigger name was added to make the interface more consistent and
  more general.
This commit is contained in:
Monty
2020-12-14 15:57:04 +02:00
committed by Sergei Golubchik
parent e3cfb7c803
commit 407e9b78cf
6 changed files with 378 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

69
sql/sql_trigger.cc
View File

@ -26,13 +26,14 @@
#include "parse_file.h"
#include "sp.h"
#include "sql_base.h"
#include "sql_show.h" // append_definer, append_identifier
#include "sql_table.h" // build_table_filename,
// check_n_cut_mysql50_prefix
#include "sql_db.h" // get_default_db_collation
#include "sql_handler.h" // mysql_ha_rm_tables
#include "sql_show.h" // append_definer, append_identifier
#include "sql_table.h" // build_table_filename,
// check_n_cut_mysql50_prefix
#include "sql_db.h" // get_default_db_collation
#include "sql_handler.h" // mysql_ha_rm_tables
#include "sp_cache.h" // sp_invalidate_cache
#include <mysys_err.h>
#include <ddl_log.h> // ddl_log_state
#include "debug_sync.h"
#include "mysql/psi/mysql_sp.h"
@ -401,10 +402,12 @@ bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create)
MDL_ticket *mdl_ticket= NULL;
MDL_request mdl_request_for_trn;
Query_tables_list backup;
DDL_LOG_STATE ddl_log_state;
DBUG_ENTER("mysql_create_or_drop_trigger");
/* Charset of the buffer for statement must be system one. */
stmt_query.set_charset(system_charset_info);
bzero(&ddl_log_state, sizeof(ddl_log_state));
/*
QQ: This function could be merged in mysql_alter_table() function
@ -604,9 +607,15 @@ bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create)
};);
#endif /* WITH_WSREP */
result= (create ?
table->triggers->create_trigger(thd, tables, &stmt_query):
table->triggers->drop_trigger(thd, tables, &stmt_query));
if (create)
result= table->triggers->create_trigger(thd, tables, &stmt_query);
else
{
result= table->triggers->drop_trigger(thd, tables,
&thd->lex->spname->m_name,
&stmt_query,
&ddl_log_state);
}
close_all_tables_for_name(thd, table->s, HA_EXTRA_NOT_USED, NULL);
@ -626,7 +635,15 @@ bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create)
end:
if (!result)
{
debug_crash_here("ddl_log_drop_before_binlog");
thd->binlog_xid= thd->query_id;
ddl_log_update_xid(&ddl_log_state, thd->binlog_xid);
result= write_bin_log(thd, TRUE, stmt_query.ptr(), stmt_query.length());
thd->binlog_xid= 0;
debug_crash_here("ddl_log_drop_after_binlog");
}
ddl_log_complete(&ddl_log_state);
/*
If we are under LOCK TABLES we should restore original state of
@ -869,13 +886,13 @@ bool Table_triggers_list::create_trigger(THD *thd, TABLE_LIST *tables,
{
if (lex->create_info.or_replace())
{
String drop_trg_query;
LEX_CSTRING *sp_name= &thd->lex->spname->m_name; // alias
/*
The following can fail if the trigger is for another table or
there exists a .TRN file but there was no trigger for it in
the .TRG file
*/
if (unlikely(drop_trigger(thd, tables, &drop_trg_query)))
if (unlikely(drop_trigger(thd, tables, sp_name, 0, 0)))
DBUG_RETURN(true);
}
else if (lex->create_info.if_not_exists())
@ -1069,8 +1086,8 @@ static bool rm_trigger_file(char *path, const LEX_CSTRING *db,
True error
*/
static bool rm_trigname_file(char *path, const LEX_CSTRING *db,
const LEX_CSTRING *trigger_name, myf MyFlags)
bool rm_trigname_file(char *path, const LEX_CSTRING *db,
const LEX_CSTRING *trigger_name, myf MyFlags)
{
build_table_filename(path, FN_REFLEN - 1, db->str, trigger_name->str,
TRN_EXT, 0);
@ -1168,13 +1185,15 @@ Trigger *Table_triggers_list::find_trigger(const LEX_CSTRING *name,
*/
bool Table_triggers_list::drop_trigger(THD *thd, TABLE_LIST *tables,
String *stmt_query)
LEX_CSTRING *sp_name,
String *stmt_query,
DDL_LOG_STATE *ddl_log_state)
{
const LEX_CSTRING *sp_name= &thd->lex->spname->m_name; // alias
char path[FN_REFLEN];
Trigger *trigger;
stmt_query->set(thd->query(), thd->query_length(), stmt_query->charset());
if (stmt_query)
stmt_query->set(thd->query(), thd->query_length(), stmt_query->charset());
/* Find and delete trigger from list */
if (!(trigger= find_trigger(sp_name, true)))
@ -1184,6 +1203,22 @@ bool Table_triggers_list::drop_trigger(THD *thd, TABLE_LIST *tables,
return 1;
}
{
LEX_CSTRING query= {0,0};
if (stmt_query)
{
/* This code is executed in case of DROP TRIGGER */
lex_string_set3(&query, thd->query(), thd->query_length());
}
if (ddl_log_state)
if (ddl_log_drop_trigger(thd, ddl_log_state,
&tables->db, &tables->table_name,
sp_name, &query))
return 1;
}
debug_crash_here("ddl_log_drop_before_drop_trigger");
if (!count) // If no more triggers
{
/*
@ -1201,9 +1236,13 @@ bool Table_triggers_list::drop_trigger(THD *thd, TABLE_LIST *tables,
return 1;
}
debug_crash_here("ddl_log_drop_before_drop_trn");
if (rm_trigname_file(path, &tables->db, sp_name, MYF(MY_WME)))
return 1;
debug_crash_here("ddl_log_drop_after_drop_trigger");
delete trigger;
return 0;
}