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synced 2025-07-30 16:24:05 +03:00
WL#1218 "Triggers". Some very preliminary version of patch.
Mostly needed for Monty for him getting notion what needed for triggers from new .FRM format. Things to be done: - Right placement of trigger's invocations - Right handling of errors in triggers (including transaction rollback) - Support for priviliges - Right handling of DROP/RENAME table (hope that it will be handled automatically with merging of .TRG into .FRM file) - Saving/restoring some information critical for trigger creation and replication with their definitions (e.g. sql_mode, creator, ...) - Replication Already has some known bugs so probably not for general review.
This commit is contained in:
dlenev@brandersnatch.localdomain
434
sql/sql_trigger.cc
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434
sql/sql_trigger.cc
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@ -0,0 +1,434 @@
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#include "mysql_priv.h"
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#include "sp_head.h"
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#include "sql_trigger.h"
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#include "parse_file.h"
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static const LEX_STRING triggers_file_type= {(char *)"TRIGGERS", 8};
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static const char * const triggers_file_ext= ".TRG";
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/*
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Table of .TRG file field descriptors.
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We have here only one field now because in nearest future .TRG
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files will be merged into .FRM files (so we don't need something
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like md5 or created fields).
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*/
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static File_option triggers_file_parameters[]=
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{
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{{(char*)"triggers", 8}, offsetof(Table_triggers_list, definitions_list),
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FILE_OPTIONS_STRLIST},
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{{NULL, 0}, 0, FILE_OPTIONS_STRING}
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};
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/*
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Create or drop trigger for table.
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SYNOPSIS
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mysql_create_or_drop_trigger()
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thd - current thread context (including trigger definition in LEX)
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tables - table list containing one table for which trigger is created.
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create - whenever we create (true) or drop (false) trigger
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NOTE
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This function is mainly responsible for opening and locking of table and
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invalidation of all its instances in table cache after trigger creation.
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Real work on trigger creation/dropping is done inside Table_triggers_list
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methods.
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RETURN VALUE
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0 - Success, non-0 in case of error.
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*/
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int mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create)
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{
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TABLE *table;
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int result= 0;
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DBUG_ENTER("mysql_create_or_drop_trigger");
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/*
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QQ: This function could be merged in mysql_alter_table() function
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But do we want this ?
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*/
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if (open_and_lock_tables(thd, tables))
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DBUG_RETURN(-1);
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// TODO: We should check if user has TRIGGER privilege for table here.
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table= tables->table;
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/*
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We do not allow creation of triggers on views or temporary tables.
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We have to do this check here and not in
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Table_triggers_list::create_trigger() because we want to avoid messing
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with table cash for views and temporary tables.
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*/
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if (tables->view || table->tmp_table != NO_TMP_TABLE)
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{
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my_error(ER_TRG_ON_VIEW_OR_TEMP_TABLE, MYF(0), tables->alias);
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DBUG_RETURN(-1);
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}
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if (!table->triggers)
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{
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if (!create)
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{
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my_error(ER_TRG_DOES_NOT_EXIST, MYF(0));
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DBUG_RETURN(-1);
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}
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if (!(table->triggers= new (&table->mem_root) Table_triggers_list()))
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DBUG_RETURN(-1);
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}
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/*
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We don't want perform our operations while global read lock is held
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so we have to wait until its end and then prevent it from occuring
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again until we are done. (Acquiring LOCK_open is not enough because
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global read lock is held without helding LOCK_open).
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*/
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if (wait_if_global_read_lock(thd, 0))
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DBUG_RETURN(-1);
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VOID(pthread_mutex_lock(&LOCK_open));
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if ((create ? table->triggers->create_trigger(thd, tables):
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table->triggers->drop_trigger(thd, tables)))
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result= -1;
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/* It is sensible to invalidate table in any case */
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close_cached_table(thd, table);
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VOID(pthread_mutex_unlock(&LOCK_open));
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start_waiting_global_read_lock(thd);
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if (!result)
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send_ok(thd);
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DBUG_RETURN(result);
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}
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/*
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Create trigger for table.
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SYNOPSIS
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create_trigger()
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thd - current thread context (including trigger definition in LEX)
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tables - table list containing one open table for which trigger is
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created.
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RETURN VALUE
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False - success
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True - error
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*/
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bool Table_triggers_list::create_trigger(THD *thd, TABLE_LIST *tables)
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{
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LEX *lex= thd->lex;
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TABLE *table= tables->table;
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char dir_buff[FN_REFLEN], file_buff[FN_REFLEN];
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LEX_STRING dir, file;
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MEM_ROOT *old_global_root;
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LEX_STRING *trg_def, *name;
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List_iterator_fast<LEX_STRING> it(names_list);
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/* We don't allow creation of several triggers of the same type yet */
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if (bodies[lex->trg_chistics.event][lex->trg_chistics.action_time])
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{
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my_error(ER_TRG_ALREADY_EXISTS, MYF(0));
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return 1;
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}
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/* Let us check if trigger with the same name exists */
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while ((name= it++))
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{
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if (my_strcasecmp(system_charset_info, lex->name_and_length.str,
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name->str) == 0)
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{
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my_error(ER_TRG_ALREADY_EXISTS, MYF(0));
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return 1;
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}
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}
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/*
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Here we are creating file with triggers and save all triggers in it.
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sql_create_definition_file() files handles renaming and backup of older
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versions
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*/
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strxnmov(dir_buff, FN_REFLEN, mysql_data_home, "/", tables->db, "/", NullS);
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dir.length= unpack_filename(dir_buff, dir_buff);
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dir.str= dir_buff;
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file.length= strxnmov(file_buff, FN_REFLEN, tables->real_name,
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triggers_file_ext, NullS) - file_buff;
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file.str= file_buff;
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old_global_root= my_pthread_getspecific_ptr(MEM_ROOT*, THR_MALLOC);
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my_pthread_setspecific_ptr(THR_MALLOC, &table->mem_root);
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/*
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Soon we will invalidate table object and thus Table_triggers_list object
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so don't care about place to which trg_def->ptr points and other
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invariants (e.g. we don't bother to update names_list)
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QQ: Hmm... probably we should not care about setting up active thread
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mem_root too.
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*/
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if (!(trg_def= (LEX_STRING *)alloc_root(&table->mem_root,
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sizeof(LEX_STRING))) ||
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definitions_list.push_back(trg_def))
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{
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my_pthread_setspecific_ptr(THR_MALLOC, old_global_root);
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return 1;
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}
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trg_def->str= thd->query;
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trg_def->length= thd->query_length;
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my_pthread_setspecific_ptr(THR_MALLOC, old_global_root);
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return sql_create_definition_file(&dir, &file, &triggers_file_type,
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(gptr)this, triggers_file_parameters, 3);
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}
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/*
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Drop trigger for table.
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SYNOPSIS
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drop_trigger()
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thd - current thread context (including trigger definition in LEX)
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tables - table list containing one open table for which trigger is
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dropped.
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RETURN VALUE
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False - success
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True - error
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*/
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bool Table_triggers_list::drop_trigger(THD *thd, TABLE_LIST *tables)
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{
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LEX *lex= thd->lex;
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LEX_STRING *name;
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List_iterator_fast<LEX_STRING> it_name(names_list);
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List_iterator<LEX_STRING> it_def(definitions_list);
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while ((name= it_name++))
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{
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it_def++;
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if (my_strcasecmp(system_charset_info, lex->name_and_length.str,
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name->str) == 0)
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{
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/*
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Again we don't care much about other things required for
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clean trigger removing since table will be reopened anyway.
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*/
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it_def.remove();
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if (definitions_list.is_empty())
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{
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char path[FN_REFLEN];
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/*
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TODO: Probably instead of removing .TRG file we should move
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to archive directory but this should be done as part of
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parse_file.cc functionality (because we will need it
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elsewhere).
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*/
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strxnmov(path, FN_REFLEN, mysql_data_home, "/", tables->db, "/",
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tables->real_name, triggers_file_ext, NullS);
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unpack_filename(path, path);
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return my_delete(path, MYF(MY_WME));
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}
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else
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{
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char dir_buff[FN_REFLEN], file_buff[FN_REFLEN];
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LEX_STRING dir, file;
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strxnmov(dir_buff, FN_REFLEN, mysql_data_home, "/", tables->db,
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"/", NullS);
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dir.length= unpack_filename(dir_buff, dir_buff);
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dir.str= dir_buff;
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file.length= strxnmov(file_buff, FN_REFLEN, tables->real_name,
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triggers_file_ext, NullS) - file_buff;
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file.str= file_buff;
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return sql_create_definition_file(&dir, &file, &triggers_file_type,
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(gptr)this,
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triggers_file_parameters, 3);
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}
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}
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}
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my_error(ER_TRG_DOES_NOT_EXIST, MYF(0));
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return 1;
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}
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Table_triggers_list::~Table_triggers_list()
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{
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for (int i= 0; i < 3; i++)
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for (int j= 0; j < 2; j++)
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delete bodies[i][j];
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if (old_field)
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for (Field **fld_ptr= old_field; *fld_ptr; fld_ptr++)
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delete *fld_ptr;
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}
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/*
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Check whenever .TRG file for table exist and load all triggers it contains.
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SYNOPSIS
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check_n_load()
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thd - current thread context
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db - table's database name
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table_name - table's name
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table - pointer to table object
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RETURN VALUE
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False - success
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True - error
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*/
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bool Table_triggers_list::check_n_load(THD *thd, const char *db,
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const char *table_name, TABLE *table)
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{
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char path_buff[FN_REFLEN];
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LEX_STRING path;
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File_parser *parser;
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MEM_ROOT *old_global_mem_root;
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DBUG_ENTER("Table_triggers_list::check_n_load");
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strxnmov(path_buff, FN_REFLEN, mysql_data_home, "/", db, "/", table_name,
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triggers_file_ext, NullS);
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path.length= unpack_filename(path_buff, path_buff);
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path.str= path_buff;
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// QQ: should we analyze errno somehow ?
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if (access(path_buff, F_OK))
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DBUG_RETURN(0);
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/*
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File exists so we got to load triggers
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FIXME: A lot of things to do here e.g. how about other funcs and being
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more paranoical ?
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*/
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if ((parser= sql_parse_prepare(&path, &table->mem_root, 1)))
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{
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if (!strncmp(triggers_file_type.str, parser->type()->str,
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parser->type()->length))
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{
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int i;
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Table_triggers_list *triggers_info=
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new (&table->mem_root) Table_triggers_list();
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if (!triggers_info)
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DBUG_RETURN(1);
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if (parser->parse((gptr)triggers_info, &table->mem_root,
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triggers_file_parameters, 1))
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DBUG_RETURN(1);
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table->triggers= triggers_info;
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/*
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We have to prepare array of Field objects which will represent OLD.*
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row values by referencing to record[1] instead of record[0]
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TODO: This could be avoided if there is no ON UPDATE trigger.
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*/
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if (!(triggers_info->old_field=
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(Field **)alloc_root(&table->mem_root, (table->fields + 1) *
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sizeof(Field*))))
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DBUG_RETURN(1);
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for (i= 0; i < table->fields; i++)
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{
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/*
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QQ: it is supposed that it is ok to use this function for field
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cloning...
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*/
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if (!(triggers_info->old_field[i]=
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table->field[i]->new_field(&table->mem_root, table)))
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DBUG_RETURN(1);
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triggers_info->old_field[i]->move_field((my_ptrdiff_t)
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(table->record[1] -
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table->record[0]));
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}
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triggers_info->old_field[i]= 0;
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List_iterator_fast<LEX_STRING> it(triggers_info->definitions_list);
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LEX_STRING *trg_create_str, *trg_name_str;
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char *trg_name_buff;
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LEX *old_lex= thd->lex, lex;
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thd->lex= &lex;
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while ((trg_create_str= it++))
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{
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lex_start(thd, (uchar*)trg_create_str->str, trg_create_str->length);
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mysql_init_query(thd, true);
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lex.trg_table= table;
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if (yyparse((void *)thd) || thd->is_fatal_error)
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{
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/*
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Free lex associated resources
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QQ: Do we really need all this stuff here ?
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*/
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if (lex.sphead)
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{
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if (&lex != thd->lex)
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thd->lex->sphead->restore_lex(thd);
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delete lex.sphead;
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}
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goto err_with_lex_cleanup;
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}
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triggers_info->bodies[lex.trg_chistics.event]
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[lex.trg_chistics.action_time]= lex.sphead;
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lex.sphead= 0;
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if (!(trg_name_buff= alloc_root(&table->mem_root,
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sizeof(LEX_STRING) +
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lex.name_and_length.length + 1)))
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goto err_with_lex_cleanup;
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trg_name_str= (LEX_STRING *)trg_name_buff;
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trg_name_buff+= sizeof(LEX_STRING);
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memcpy(trg_name_buff, lex.name_and_length.str,
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lex.name_and_length.length + 1);
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trg_name_str->str= trg_name_buff;
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trg_name_str->length= lex.name_and_length.length;
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old_global_mem_root= my_pthread_getspecific_ptr(MEM_ROOT*, THR_MALLOC);
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my_pthread_setspecific_ptr(THR_MALLOC, &table->mem_root);
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if (triggers_info->names_list.push_back(trg_name_str))
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goto err_with_lex_cleanup;
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my_pthread_setspecific_ptr(THR_MALLOC, old_global_mem_root);
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lex_end(&lex);
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}
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thd->lex= old_lex;
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DBUG_RETURN(0);
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err_with_lex_cleanup:
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// QQ: anything else ?
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lex_end(&lex);
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thd->lex= old_lex;
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DBUG_RETURN(1);
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}
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/*
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We don't care about this error message much because .TRG files will
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be merged into .FRM anyway.
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*/
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my_error(ER_WRONG_OBJECT, MYF(0), table_name, triggers_file_ext, "TRIGGER");
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DBUG_RETURN(1);
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}
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DBUG_RETURN(1);
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}
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