emkornfield commented on code in PR #50916:
URL: https://github.com/apache/arrow/pull/50916#discussion_r3921796186
##########
cpp/src/parquet/arrow/reader_internal.cc:
##########
@@ -855,6 +856,49 @@ Status TransferHalfFloat(RecordReader* reader, MemoryPool*
pool,
return Status::OK();
}
+// Read a TIMESTAMP-annotated FLBA(12) column as a 64-bit Arrow timestamp.
Values that do
+// not fit in the 64 bit range either error or clamp to min/max int64,
depending on
+// configuration.
+Status TransferFlbaTimestamp(RecordReader* reader, MemoryPool* pool,
+ const std::shared_ptr<Field>& field, Datum* out,
+ bool clamp_on_overflow) {
+ static const auto binary_type = ::arrow::fixed_size_binary(12);
+ std::shared_ptr<ChunkedArray> chunked_array;
+ RETURN_NOT_OK(
+ TransferBinary(reader, pool, field->WithType(binary_type),
&chunked_array));
+
+ ::arrow::TimestampBuilder builder(field->type(), pool);
+ RETURN_NOT_OK(builder.Reserve(chunked_array->length()));
+ for (const auto& chunk : chunked_array->chunks()) {
+ const auto& values = checked_cast<const
::arrow::FixedSizeBinaryArray&>(*chunk);
+ for (int64_t i = 0; i < values.length(); ++i) {
+ if (values.IsNull(i)) {
+ builder.UnsafeAppendNull();
+ continue;
+ }
+ const uint8_t* bytes = values.GetValue(i);
+ const uint64_t low =
bit_util::FromLittleEndian(SafeLoadAs<uint64_t>(bytes));
+ const uint32_t high =
bit_util::FromLittleEndian(SafeLoadAs<uint32_t>(bytes + 8));
+ const int64_t low_signed = static_cast<int64_t>(low);
+ // Fits in int64 iff the high part is a pure sign-extension of the low
part.
+ if (static_cast<int32_t>(high) != (low_signed < 0 ? -1 : 0)) {
+ if (!clamp_on_overflow) {
+ return Status::Invalid(
+ "FLBA(12) TIMESTAMP value does not fit in a 64-bit Arrow
timestamp");
+ }
+ const bool negative = (bytes[11] & 0x80) != 0;
Review Comment:
why not re-use low_signed and do a copmarison against it?
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