def table(schema, name=None):
"""
Create an unbound Ibis table for creating expressions. Cannot be executed
without being bound to some physical table.
Useful for testing
Parameters
----------
schema : ibis Schema
name : string, default None
Name for table
Returns
-------
table : TableExpr
"""
if not isinstance(schema, Schema):
if isinstance(schema, list):
schema = Schema.from_tuples(schema)
else:
schema = Schema.from_dict(schema)
node = _ops.UnboundTable(schema, name=name)
return TableExpr(node)
def table(schema, name=None):
"""
Create an unbound Ibis table for creating expressions. Cannot be executed
without being bound to some physical table.
Useful for testing
Parameters
----------
schema : ibis Schema
name : string, default None
Name for table
Returns
-------
table : TableExpr
"""
if not isinstance(schema, Schema):
if isinstance(schema, list):
schema = Schema.from_tuples(schema)
else:
schema = Schema.from_dict(schema)
node = _ops.UnboundTable(schema, name=name)
return TableExpr(node)
def get_schema(self, table_name, database=None):
"""
Return a Schema object for the indicated table and database
Parameters
----------
table_name : string
May be fully qualified
database : string, default None
Returns
-------
schema : ibis Schema
"""
qualified_name = self._fully_qualified_name(table_name, database)
query = 'DESCRIBE {0}'.format(qualified_name)
tuples = self.con.fetchall(query)
names, types, comments = zip(*tuples)
ibis_types = []
for t in types:
t = t.lower()
t = udf._impala_to_ibis_type.get(t, t)
ibis_types.append(t)
names = [x.lower() for x in names]
return Schema(names, ibis_types)
def get_partition_schema(self, table_name, database=None):
"""
For partitioned tables, return the schema (names and types) for the
partition columns
Parameters
----------
table_name : string
May be fully qualified
database : string, default None
Returns
-------
partition_schema : ibis Schema
"""
qualified_name = self._fully_qualified_name(table_name, database)
schema = self.get_schema(table_name, database=database)
name_to_type = dict(zip(schema.names, schema.types))
query = 'SHOW PARTITIONS {0}'.format(qualified_name)
partition_fields = []
with self._execute(query, results=True) as cur:
result = self._fetch_from_cursor(cur)
for x in result.columns:
if x not in name_to_type:
break
partition_fields.append((x, name_to_type[x]))
pnames, ptypes = zip(*partition_fields)
return Schema(pnames, ptypes)
def _result_schema(self):
names = []
types = []
# All exprs must be named
for e in self.by + self.agg_exprs:
names.append(e.get_name())
types.append(e.type())
return Schema(names, types)
def _get_schema_using_query(self, query):
with self._execute(query, results=True) as cur:
# resets the state of the cursor and closes operation
cur.fetchall()
names, ibis_types = self._adapt_types(cur.description)
# per #321; most Impala tables will be lower case already, but Avro
# data, depending on the version of Impala, might have field names in
# the metastore cased according to the explicit case in the declared
# avro schema. This is very annoying, so it's easier to just conform on
# all lowercase fields from Impala.
names = [x.lower() for x in names]
return Schema(names, ibis_types)
def __init__(self, table_expr, proj_exprs):
from ibis.expr.analysis import ExprValidator
# Need to validate that the column expressions are compatible with the
# input table; this means they must either be scalar expressions or
# array expressions originating from the same root table expression
validator = ExprValidator([table_expr])
# Resolve schema and initialize
types = []
names = []
clean_exprs = []
for expr in proj_exprs:
if isinstance(expr, py_string):
expr = table_expr[expr]
validator.assert_valid(expr)
if isinstance(expr, ValueExpr):
name = expr.get_name()
names.append(name)
types.append(expr.type())
elif rules.is_table(expr):
schema = expr.schema()
names.extend(schema.names)
types.extend(schema.types)
else:
raise NotImplementedError
clean_exprs.append(expr)
# validate uniqueness
schema = Schema(names, types)
HasSchema.__init__(self, schema)
Node.__init__(self, [table_expr] + [clean_exprs])
self.table = table_expr
self.selections = clean_exprs
def _get_table_schema(self, name):
name = name.replace('`', '')
return Schema.from_tuples(self._tables[name])
def schema(pairs=None, names=None, types=None):
if pairs is not None:
return Schema.from_tuples(pairs)
else:
return Schema(names, types)
def schema(pairs=None, names=None, types=None):
if pairs is not None:
return Schema.from_tuples(pairs)
else:
return Schema(names, types)
