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MDEV-34724: Skipping a row operation from a trigger

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Implementation of this task adds ability to raise the signal with
SQLSTATE '02TRG' from a BEFORE INSERT/UPDATE/DELETE trigger and handles
this signal as an indicator meaning 'to throw away the current row'
on processing the INSERT/UPDATE/DELETE statement. The signal with
SQLSTATE '02TRG' has special meaning only in case it is raised inside
BEFORE triggers, for AFTER trigger's this value of SQLSTATE isn't treated
in any special way. In according with SQL standard, the SQLSTATE class '02'
means NO DATA and sql_errno for this class is set to value
ER_SIGNAL_NOT_FOUND by current implementation of MariaDB server.
Implementation of this task assigns the value ER_SIGNAL_SKIP_ROW_FROM_TRIGGER
to sql_errno in Diagnostics_area in case the signal is raised from a trigger
and SQLSTATE has value '02TRG'.

To catch signal with SQLTSATE '02TRG' and handle it in special way, the methods
 Table_triggers_list::process_triggers
 select_insert::store_values
 select_create::store_values
 Rows_log_event::process_triggers
and the overloaded function
 fill_record_n_invoke_before_triggers
were extended with extra out parameter for returning the flag whether
to skip the current values being processed by INSERT/UPDATE/DELETE
statement. This extra parameter is passed as nullptr in case of AFTER trigger
and BEFORE trigger this parameter points to a variable to store a marker
whether to skip the current record or store it by calling write_record().
This commit is contained in:
Dmitry Shulga
2025-01-27 16:29:25 +07:00
parent fcf7211136
commit 4c956fa15b
17 changed files with 1097 additions and 64 deletions
Download Patch File Download Diff File Expand all files Collapse all files

57
sql/sql_insert.cc
View File

@ -1057,6 +1057,8 @@ bool mysql_insert(THD *thd, TABLE_LIST *table_list,
while ((values= its++))
{
bool trg_skip_row= false;
thd->get_stmt_da()->inc_current_row_for_warning();
if (fields.elements || !value_count)
{
@ -1070,7 +1072,8 @@ bool mysql_insert(THD *thd, TABLE_LIST *table_list,
if (unlikely(fill_record_n_invoke_before_triggers(thd, table, fields,
*values, 0,
TRG_EVENT_INSERT)))
TRG_EVENT_INSERT,
&trg_skip_row)))
{
if (values_list.elements != 1 && ! thd->is_error())
{
@ -1119,7 +1122,8 @@ bool mysql_insert(THD *thd, TABLE_LIST *table_list,
table->
field_to_fill(),
*values, 0,
TRG_EVENT_INSERT)))
TRG_EVENT_INSERT,
&trg_skip_row)))
{
if (values_list.elements != 1 && ! thd->is_error())
{
@ -1131,6 +1135,8 @@ bool mysql_insert(THD *thd, TABLE_LIST *table_list,
}
}
if (trg_skip_row)
continue;
/*
with triggers a field can get a value *conditionally*, so we have to
repeat has_no_default_value() check for every row
@ -2077,13 +2083,20 @@ int write_record(THD *thd, TABLE *table, COPY_INFO *info, select_result *sink)
*/
DBUG_ASSERT(info->update_fields->elements ==
info->update_values->elements);
bool trg_skip_row= false;
if (fill_record_n_invoke_before_triggers(thd, table,
*info->update_fields,
*info->update_values,
info->ignore,
TRG_EVENT_UPDATE))
TRG_EVENT_UPDATE,
&trg_skip_row))
goto before_trg_err;
if (trg_skip_row)
goto ok;
bool different_records= (!records_are_comparable(table) ||
compare_record(table));
/*
@ -2158,7 +2171,8 @@ int write_record(THD *thd, TABLE *table, COPY_INFO *info, select_result *sink)
insert_id_for_cur_row= table->file->insert_id_for_cur_row= 0;
trg_error= (table->triggers &&
table->triggers->process_triggers(thd, TRG_EVENT_UPDATE,
TRG_ACTION_AFTER, TRUE));
TRG_ACTION_AFTER, true,
nullptr));
info->copied++;
}
@ -2254,11 +2268,17 @@ int write_record(THD *thd, TABLE *table, COPY_INFO *info, select_result *sink)
}
else
{
bool trg_skip_row= false;
if (table->triggers &&
table->triggers->process_triggers(thd, TRG_EVENT_DELETE,
TRG_ACTION_BEFORE, TRUE))
TRG_ACTION_BEFORE, true,
&trg_skip_row))
goto before_trg_err;
if (trg_skip_row)
continue;
if (!table->versioned(VERS_TIMESTAMP))
error= table->file->ha_delete_row(table->record[1]);
else
@ -2280,7 +2300,8 @@ int write_record(THD *thd, TABLE *table, COPY_INFO *info, select_result *sink)
thd->transaction->stmt.modified_non_trans_table= TRUE;
if (table->triggers &&
table->triggers->process_triggers(thd, TRG_EVENT_DELETE,
TRG_ACTION_AFTER, TRUE))
TRG_ACTION_AFTER, true,
nullptr))
{
trg_error= 1;
goto after_trg_or_ignored_err;
@ -2327,7 +2348,8 @@ after_trg_n_copied_inc:
thd->record_first_successful_insert_id_in_cur_stmt(table->file->insert_id_for_cur_row);
trg_error= (table->triggers &&
table->triggers->process_triggers(thd, TRG_EVENT_INSERT,
TRG_ACTION_AFTER, TRUE));
TRG_ACTION_AFTER, true,
nullptr));
ok:
/*
@ -4279,9 +4301,10 @@ int select_insert::send_data(List<Item> &values)
{
DBUG_ENTER("select_insert::send_data");
bool error=0;
bool trg_skip_row= false;
thd->count_cuted_fields= CHECK_FIELD_WARN; // Calculate cuted fields
if (store_values(values))
if (store_values(values, &trg_skip_row))
DBUG_RETURN(1);
thd->count_cuted_fields= CHECK_FIELD_ERROR_FOR_NULL;
if (unlikely(thd->is_error()))
@ -4300,10 +4323,11 @@ int select_insert::send_data(List<Item> &values)
}
}
error= write_record(thd, table, &info, sel_result);
if (!trg_skip_row)
error= write_record(thd, table, &info, sel_result);
table->auto_increment_field_not_null= FALSE;
if (likely(!error))
if (likely(!error) && !trg_skip_row)
{
if (table->triggers || info.handle_duplicates == DUP_UPDATE)
{
@ -4337,7 +4361,7 @@ int select_insert::send_data(List<Item> &values)
}
bool select_insert::store_values(List<Item> &values)
bool select_insert::store_values(List<Item> &values, bool *trg_skip_row)
{
DBUG_ENTER("select_insert::store_values");
bool error;
@ -4345,10 +4369,12 @@ bool select_insert::store_values(List<Item> &values)
table->reset_default_fields();
if (fields->elements)
error= fill_record_n_invoke_before_triggers(thd, table, *fields, values,
true, TRG_EVENT_INSERT);
true, TRG_EVENT_INSERT,
trg_skip_row);
else
error= fill_record_n_invoke_before_triggers(thd, table, table->field_to_fill(),
values, true, TRG_EVENT_INSERT);
values, true, TRG_EVENT_INSERT,
trg_skip_row);
DBUG_RETURN(error);
}
@ -5138,10 +5164,11 @@ bool binlog_drop_table(THD *thd, TABLE *table)
}
bool select_create::store_values(List<Item> &values)
bool select_create::store_values(List<Item> &values, bool *trg_skip_row)
{
return fill_record_n_invoke_before_triggers(thd, table, field, values,
true, TRG_EVENT_INSERT);
true, TRG_EVENT_INSERT,
trg_skip_row);
}