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import sqlalchemy.schema as sa_schema
from sqlalchemy.engine.reflection import Inspector
from sqlalchemy.orm.exc import NoResultFound
from clickhouse_connect.cc_sqlalchemy.datatypes.base import sqla_type_from_name
from clickhouse_connect.cc_sqlalchemy.ddl.tableengine import build_engine
from clickhouse_connect.cc_sqlalchemy.sql import full_table
from clickhouse_connect.cc_sqlalchemy import dialect_name as dn
ch_col_args = ('default_type', 'codec_expression', 'ttl_expression')
def get_engine(connection, table_name, schema=None):
result_set = connection.execute(
f"SELECT engine_full FROM system.tables WHERE database = '{schema}' and name = '{table_name}'")
row = next(result_set, None)
if not row:
raise NoResultFound(f'Table {schema}.{table_name} does not exist')
return build_engine(row.engine_full)
class ChInspector(Inspector):
def reflect_table(self, table, include_columns, exclude_columns, *_args, **_kwargs):
schema = table.schema
for col in self.get_columns(table.name, schema):
name = col.pop('name')
if (include_columns and name not in include_columns) or (exclude_columns and name in exclude_columns):
continue
col_type = col.pop('type')
col_args = {f'{dn}_{key}' if key in ch_col_args else key: value for key, value in col.items() if value}
table.append_column(sa_schema.Column(name, col_type, **col_args))
table.engine = get_engine(self.bind, table.name, schema)
def get_columns(self, table_name, schema=None, **_kwargs):
table_id = full_table(table_name, schema)
result_set = self.bind.execute(f'DESCRIBE TABLE {table_id}')
if not result_set:
raise NoResultFound(f'Table {full_table} does not exist')
columns = []
for row in result_set:
sqla_type = sqla_type_from_name(row.type.replace('\n', ''))
col = {'name': row.name,
'type': sqla_type,
'nullable': sqla_type.nullable,
'autoincrement': False,
'default': row.default_expression,
'default_type': row.default_type,
'comment': row.comment,
'codec_expression': row.codec_expression,
'ttl_expression': row.ttl_expression}
columns.append(col)
return columns
ChInspector.reflecttable = ChInspector.reflect_table # Hack to provide backward compatibility for SQLAlchemy 1.3
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