def _has_index(attribute_name, table_name):
metadata = load_metadata()
for index_name, index in metadata.tables[table_name].indexes.items():
if attribute_name in index.columns:
file_path = RecordManager.file_dir + index_name + '.index'
fmt = metadata.tables[table_name].columns[attribute_name].fmt
manager = IndexManager(file_path, fmt)
try:
manager.iter_leaves()
return index_name
except RuntimeError:
pass
else:
pass
return None
def _select_single_condition(table_name, condition):
metadata = load_metadata()
index_name = MinisqlFacade._has_index(condition[0], table_name)
if index_name:
print('select with index on ', condition[0])
attribute_name = condition[0]
operator = condition[1]
key_list = list()
key_list.append(condition[2])
file_path = RecordManager.file_dir + index_name + '.index' #
fmt = metadata.tables[table_name].columns[attribute_name].fmt
manager = IndexManager(file_path, fmt)
records = list()
if operator == '=':
try:
itr = manager.find(key_list)
it_key, value = next(itr)
if it_key[0] == key_list[0]:
records.append(
RecordManager.select(
table_name,
metadata.tables[table_name].fmt,
with_index=True,
record_offset=value))
except StopIteration:
pass
elif operator == '>':
for i in manager.find(key_list):
if i[0][0] > key_list[0]:
value = i[1]
records.append(
RecordManager.select(
table_name,
metadata.tables[table_name].fmt,
with_index=True,
record_offset=value))
elif operator == '<':
for i in manager.iter_leaves():
if i[0][0] < key_list[0]:
value = i[1]
records.append(
RecordManager.select(
table_name,
metadata.tables[table_name].fmt,
with_index=True,
record_offset=value))
else:
break
else:
pass
else:
records = MinisqlFacade.select_record_conditionally_without_index(
table_name, condition)
return records
def drop_index(index_name):
metadata = load_metadata()
for table_name, table in metadata.tables.items():
if index_name in table.indexes:
file_path = 'schema/tables/' + table_name + '/' + index_name + '.index'
fmt = ''.join(metadata.tables[table_name].columns[column].fmt
for column in table.indexes[index_name].columns)
manager = IndexManager(file_path, fmt)
metadata.drop_index(table_name, index_name)
try:
for i in manager.iter_leaves():
key_list = list()
key_list.append(i[0][0])
manager.delete(key_list)
except RuntimeError:
pass
metadata.dump()
def delete_record_all(table_name):
RecordManager.set_file_dir('schema/tables/' + table_name + '/')
metadata = load_metadata()
RecordManager.delete(table_name,
metadata.tables[table_name].fmt,
with_index=False,
conditions={})
for index_name, index in metadata.tables[table_name].indexes.items():
file_path = RecordManager.file_dir + index_name + '.index'
fmt = ''.join(metadata.tables[table_name].columns[column].fmt
for column in index.columns)
manager = IndexManager(file_path, fmt)
try:
for i in manager.iter_leaves():
key_list = list()
key_list.append(i[0][0])
manager.delete(key_list)
except RuntimeError:
pass