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MDEV-11114 Cannot drop column referenced by CHECK constraint

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SQL Standard behavior for DROP COLUMN xxx RESTRICT:
* If a constraint (UNIQUE or CHECK) uses only the dropped column,
  it's automatically dropped too. If it uses many columns - an error.
This commit is contained in:
Sergei Golubchik
2017-08-12 18:52:38 +02:00
parent 28ddc9b3bb
commit 04b288ae47
17 changed files with 121 additions and 200 deletions
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28
sql/sql_table.cc
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@@ -7549,6 +7549,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
bool modified_primary_key= FALSE;
Create_field *def;
Field **f_ptr,*field;
MY_BITMAP *dropped_fields= NULL; // if it's NULL - no dropped fields
DBUG_ENTER("mysql_prepare_alter_table");
/*
@@ -7605,6 +7606,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
/*
First collect all fields from table which isn't in drop_list
*/
bitmap_clear_all(&table->tmp_set);
for (f_ptr=table->field ; (field= *f_ptr) ; f_ptr++)
{
Alter_drop *drop;
@@ -7630,6 +7632,8 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
if (table->s->tmp_table == NO_TMP_TABLE)
(void) delete_statistics_for_column(thd, table, field);
drop_it.remove();
dropped_fields= &table->tmp_set;
bitmap_set_bit(dropped_fields, field->field_index);
continue;
}
/* Check if field is changed */
@@ -7816,6 +7820,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
continue;
}
const char *dropped_key_part= NULL;
KEY_PART_INFO *key_part= key_info->key_part;
key_parts.empty();
bool delete_index_stat= FALSE;
@@ -7845,6 +7850,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
if (table->s->primary_key == i)
modified_primary_key= TRUE;
delete_index_stat= TRUE;
dropped_key_part= key_part_name;
continue; // Field is removed
}
key_part_length= key_part->length;
@@ -7927,6 +7933,11 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
key_type= Key::PRIMARY;
else
key_type= Key::UNIQUE;
if (dropped_key_part)
{
my_error(ER_KEY_COLUMN_DOES_NOT_EXITS, MYF(0), dropped_key_part);
goto err;
}
}
else if (key_info->flags & HA_FULLTEXT)
key_type= Key::FULLTEXT;
@@ -7977,6 +7988,23 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
break;
}
}
/* see if the constraint depends on *only* on dropped fields */
if (dropped_fields)
{
table->default_column_bitmaps();
bitmap_clear_all(table->read_set);
check->expr->walk(&Item::register_field_in_read_map, 1, 0);
if (bitmap_is_subset(table->read_set, dropped_fields))
drop= (Alter_drop*)1;
else if (bitmap_is_overlapping(dropped_fields, table->read_set))
{
bitmap_intersect(table->read_set, dropped_fields);
uint field_nr= bitmap_get_first_set(table->read_set);
my_error(ER_BAD_FIELD_ERROR, MYF(0),
table->field[field_nr]->field_name, "CHECK");
goto err;
}
}
if (!drop)
new_constraint_list.push_back(check, thd->mem_root);
}