maxdebayser commented on code in PR #7831:
URL: https://github.com/apache/iceberg/pull/7831#discussion_r1260009439
##########
python/pyiceberg/io/pyarrow.py:
##########
@@ -1013,3 +1027,359 @@ def map_key_partner(self, partner_map:
Optional[pa.Array]) -> Optional[pa.Array]
def map_value_partner(self, partner_map: Optional[pa.Array]) ->
Optional[pa.Array]:
return partner_map.items if isinstance(partner_map, pa.MapArray) else
None
+
+
+BOUND_TRUNCATED_LENGHT = 16
+TRUNCATION_EXPR = r"^truncate\((\d+)\)$"
+
+logger = logging.getLogger(__name__)
+
+# Serialization rules:
https://iceberg.apache.org/spec/#binary-single-value-serialization
+#
+# Type Binary serialization
+# boolean 0x00 for false, non-zero byte for true
+# int Stored as 4-byte little-endian
+# long Stored as 8-byte little-endian
+# float Stored as 4-byte little-endian
+# double Stored as 8-byte little-endian
+# date Stores days from the 1970-01-01 in an 4-byte little-endian int
+# time Stores microseconds from midnight in an 8-byte little-endian long
+# timestamp without zone Stores microseconds from 1970-01-01
00:00:00.000000 in an 8-byte little-endian long
+# timestamp with zone Stores microseconds from 1970-01-01 00:00:00.000000 UTC
in an 8-byte little-endian long
+# string UTF-8 bytes (without length)
+# uuid 16-byte big-endian value, see example in Appendix B
+# fixed(L) Binary value
+# binary Binary value (without length)
+#
+
+
+def bool_to_avro(value: bool) -> bytes:
+ return STRUCT_BOOL.pack(value)
+
+
+def int32_to_avro(value: int) -> bytes:
+ return STRUCT_INT32.pack(value)
+
+
+def int64_to_avro(value: int) -> bytes:
+ return STRUCT_INT64.pack(value)
+
+
+def float_to_avro(value: float) -> bytes:
+ return STRUCT_FLOAT.pack(value)
+
+
+def double_to_avro(value: float) -> bytes:
+ return STRUCT_DOUBLE.pack(value)
+
+
+def bytes_to_avro(value: Union[bytes, str]) -> bytes:
+ if type(value) == str:
+ return value.encode()
+ else:
+ assert isinstance(value, bytes) # appeases mypy
+ return value
+
+
+class StatsAggregator:
+ def __init__(self, type_string: str, trunc_length: Optional[int] = None)
-> None:
+ self.current_min: Any = None
+ self.current_max: Any = None
+ self.serialize: Any = None
+ self.trunc_lenght = trunc_length
+
+ if type_string == "BOOLEAN":
+ self.serialize = bool_to_avro
+ elif type_string == "INT32":
+ self.serialize = int32_to_avro
+ elif type_string == "INT64":
+ self.serialize = int64_to_avro
+ elif type_string == "INT96":
+ raise NotImplementedError("Statistics not implemented for INT96
physical type")
+ elif type_string == "FLOAT":
+ self.serialize = float_to_avro
+ elif type_string == "DOUBLE":
+ self.serialize = double_to_avro
+ elif type_string == "BYTE_ARRAY":
+ self.serialize = bytes_to_avro
+ elif type_string == "FIXED_LEN_BYTE_ARRAY":
+ self.serialize = bytes_to_avro
+ else:
+ raise AssertionError(f"Unknown physical type {type_string}")
+
+ def add_min(self, val: bytes) -> None:
+ if self.current_min is None:
+ self.current_min = val
+ else:
+ self.current_min = min(val, self.current_min)
+
+ def add_max(self, val: bytes) -> None:
+ if self.current_max is None:
+ self.current_max = val
+ else:
+ self.current_max = max(self.current_max, val)
+
+ def get_min(self) -> bytes:
+ return self.serialize(self.current_min)[: self.trunc_lenght]
+
+ def get_max(self) -> bytes:
+ return self.serialize(self.current_max)[: self.trunc_lenght]
+
+
+class MetricsMode(Enum):
+ NONE = 0
+ COUNTS = 1
+ TRUNC = 2
Review Comment:
I think an Enum is a more pythonic way to define a set of constants.
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