Produce rows as slices of pyarrow.Table

pyhive/common.py

@@ -38,7 +38,7 @@ def _reset_state(self):
 
         # Internal helper state
         self._state = self._STATE_NONE
-        self._data = collections.deque()
+        self._data = None
         self._columns = None
 
     def _fetch_while(self, fn):

pyhive/hive.py

@@ -10,6 +10,10 @@
 
 import base64
 import datetime
+import io
+import numpy as np
+import pyarrow as pa
+import pyarrow.json
 import re
 from decimal import Decimal
 from ssl import CERT_NONE, CERT_OPTIONAL, CERT_REQUIRED, create_default_context
@@ -41,6 +45,7 @@
 _logger = logging.getLogger(__name__)
 
 _TIMESTAMP_PATTERN = re.compile(r'(\d+-\d+-\d+ \d+:\d+:\d+(\.\d{,6})?)')
+_INTERVAL_DAY_TIME_PATTERN = re.compile(r'(\d+) (\d+):(\d+):(\d+(?:.\d+)?)')
 
 ssl_cert_parameter_map = {
     "none": CERT_NONE,
@@ -67,9 +72,36 @@ def _parse_timestamp(value):
         value = None
     return value
 
+def _parse_date(value):
+    if value:
+        format = '%Y-%m-%d'
+        value = datetime.datetime.strptime(value, format).date()
+    else:
+        value = None
+    return value
 
-TYPES_CONVERTER = {"DECIMAL_TYPE": Decimal,
-                   "TIMESTAMP_TYPE": _parse_timestamp}
+def _parse_interval_day_time(value):
+    if value:
+        match = _INTERVAL_DAY_TIME_PATTERN.match(value)
+        if match:
+            days = int(match.group(1))
+            hours = int(match.group(2))
+            minutes = int(match.group(3))
+            seconds = float(match.group(4))
+            value = datetime.timedelta(days=days, hours=hours, minutes=minutes, seconds=seconds)
+        else:
+            raise Exception(
+                'Cannot convert "{}" into an interval_day_time'.format(value))
+    else:
+        value = None
+    return value
+
+TYPES_CONVERTER = {
+    "DECIMAL_TYPE": Decimal,
+    "TIMESTAMP_TYPE": _parse_timestamp,
+    "DATE_TYPE": _parse_date,
+    "INTERVAL_DAY_TIME_TYPE": _parse_interval_day_time,
+}
 
 
 class HiveParamEscaper(common.ParamEscaper):
@@ -462,6 +494,48 @@ def cancel(self):
         response = self._connection.client.CancelOperation(req)
         _check_status(response)
 
+    def fetchone(self):
+        return self.fetchmany(1)
+
+    def fetchall(self):
+        return self.fetchmany(-1)
+
+    def fetchmany(self, size=None):
+        if size is None:
+            size = self.arraysize
+
+        if self._state == self._STATE_NONE:
+            raise exc.ProgrammingError("No query yet")
+
+        if size == -1:
+            # Fetch everything
+            self._fetch_while(lambda: self._state != self._STATE_FINISHED)
+        else:
+            self._fetch_while(lambda: 
+                (self._state != self._STATE_FINISHED) and
+                (self._data is None or self._data.num_rows < size)
+            )
+
+        if not self._data:
+            return None
+
+        if size == -1:
+            # Fetch everything
+            size = self._data.num_rows
+        else:
+            size = min(size, self._data.num_rows)
+
+        self._rownumber += size
+        rows = self._data[:size]
+
+        if size == self._data.num_rows:
+            # Fetch everything
+            self._data = None
+        else:
+            self._data = self._data[size:]
+
+        return rows
+
     def _fetch_more(self):
         """Send another TFetchResultsReq and update state"""
         assert(self._state == self._STATE_RUNNING), "Should be running when in _fetch_more"
@@ -479,13 +553,19 @@ def _fetch_more(self):
         assert not response.results.rows, 'expected data in columnar format'
         columns = [_unwrap_column(col, col_schema[1]) for col, col_schema in
                    zip(response.results.columns, schema)]
-        new_data = list(zip(*columns))
-        self._data += new_data
+        names = [col[0] for col in schema]
+        new_data = pa.Table.from_batches([pa.RecordBatch.from_arrays(columns, names=names)])
         # response.hasMoreRows seems to always be False, so we instead check the number of rows
         # https://github.com/apache/hive/blob/release-1.2.1/service/src/java/org/apache/hive/service/cli/thrift/ThriftCLIService.java#L678
         # if not response.hasMoreRows:
-        if not new_data:
+        if new_data.num_rows == 0:
             self._state = self._STATE_FINISHED
+            return
+
+        if self._data is None:
+            self._data = new_data
+        else:
+            self._data = pa.concat_tables([self._data, new_data])
 
     def poll(self, get_progress_update=True):
         """Poll for and return the raw status data provided by the Hive Thrift REST API.
@@ -563,17 +643,42 @@ def _unwrap_column(col, type_=None):
     """Return a list of raw values from a TColumn instance."""
     for attr, wrapper in iteritems(col.__dict__):
         if wrapper is not None:
-            result = wrapper.values
-            nulls = wrapper.nulls  # bit set describing what's null
-            assert isinstance(nulls, bytes)
-            for i, char in enumerate(nulls):
-                byte = ord(char) if sys.version_info[0] == 2 else char
-                for b in range(8):
-                    if byte & (1 << b):
-                        result[i * 8 + b] = None
-            converter = TYPES_CONVERTER.get(type_, None)
-            if converter and type_:
-                result = [converter(row) if row else row for row in result]
+            if attr in ['boolVal', 'byteVal', 'i16Val', 'i32Val', 'i64Val', 'doubleVal']:
+                values = wrapper.values
+                # unpack nulls as a byte array
+                nulls = np.unpackbits(np.frombuffer(wrapper.nulls, dtype='uint8')).view(bool)
+                # override a full mask as trailing False values are not sent
+                mask = np.zeros(values.shape, dtype='?')
+                end = min(len(mask), len(nulls))
+                mask[:end] = nulls[:end]
+
+                # float values are transferred as double
+                if type_ == 'FLOAT_TYPE':
+                    values = values.astype('>f4')
+
+                result = pa.array(values.byteswap().newbyteorder(), mask=mask)
+            else:
+                result = wrapper.values
+                nulls = wrapper.nulls  # bit set describing what's null
+                if len(result) == 0:
+                    return pa.array([])
+                assert isinstance(nulls, bytes)
+                for i, char in enumerate(nulls):
+                    byte = ord(char) if sys.version_info[0] == 2 else char
+                    for b in range(8):
+                        if byte & (1 << b):
+                            result[i * 8 + b] = None
+                converter = TYPES_CONVERTER.get(type_, None)
+                if converter and type_:
+                    result = [converter(row) if row else row for row in result]
+                if type_ in ['ARRAY_TYPE', 'MAP_TYPE', 'STRUCT_TYPE']:
+                    fd = io.BytesIO()
+                    for row in result:
+                        if row is None:
+                            row = 'null'
+                        fd.write(f'{{"c":{row}}}\n'.encode('utf8'))
+                    fd.seek(0)
+                    result = pa.json.read_json(fd)[0].combine_chunks()
             return result
     raise DataError("Got empty column value {}".format(col))  # pragma: no cover