[bug](parquet) fix parquet type not handle float16 type

Author: zhangstar333

be/src/vec/exec/format/parquet/parquet_column_convert.cpp

@@ -230,6 +230,11 @@ std::unique_ptr<PhysicalToLogicalConverter> PhysicalToLogicalConverter::get_conv
             // for FixedSizeBinary
             physical_converter =
                     std::make_unique<FixedSizeBinaryConverter>(parquet_schema.type_length);
+        } else if (src_logical_primitive == TYPE_FLOAT &&
+                   src_physical_type == tparquet::Type::FIXED_LEN_BYTE_ARRAY &&
+                   parquet_schema.logicalType.__isset.FLOAT16) {
+            physical_converter =
+                    std::make_unique<Float16PhysicalConverter>(parquet_schema.type_length);
         } else {
             physical_converter = std::make_unique<ConsistentPhysicalConverter>();
         }

be/src/vec/exec/format/parquet/parquet_column_convert.h

@@ -20,6 +20,7 @@
 #include <gen_cpp/parquet_types.h>
 
 #include "common/cast_set.h"
+#include "runtime/primitive_type.h"
 #include "vec/columns/column_varbinary.h"
 #include "vec/core/extended_types.h"
 #include "vec/core/field.h"
@@ -354,6 +355,86 @@ class FixedSizeBinaryConverter : public PhysicalToLogicalConverter {
     }
 };
 
+class Float16PhysicalConverter : public PhysicalToLogicalConverter {
+private:
+    int _type_length;
+
+public:
+    Float16PhysicalConverter(int type_length) : _type_length(type_length) {
+        DCHECK_EQ(_type_length, 2);
+    }
+
+    Status physical_convert(ColumnPtr& src_physical_col, ColumnPtr& src_logical_column) override {
+        ColumnPtr from_col = remove_nullable(src_physical_col);
+        MutableColumnPtr to_col = remove_nullable(src_logical_column)->assume_mutable();
+
+        const auto* src_data = assert_cast<const ColumnUInt8*>(from_col.get());
+        size_t length = src_data->size();
+        size_t num_values = length / _type_length;
+        auto* to_float_column = assert_cast<ColumnFloat32*>(to_col.get());
+        const uint8_t* ptr = src_data->get_data().data();
+        for (int i = 0; i < num_values; ++i) {
+            size_t offset = i * _type_length;
+            const uint8_t* data_ptr = ptr + offset;
+            uint16_t raw;
+            memcpy(&raw, data_ptr, sizeof(uint16_t));
+            float value = half_to_float(raw);
+            to_float_column->insert_value(value);
+        }
+
+        return Status::OK();
+    }
+
+    float half_to_float(uint16_t h) {
+        // uint16_t h: half precision floating point
+        // bit 15:       sign（1 bit）
+        // bits 14..10 : exponent（5 bits）
+        // bits 9..0   : mantissa（10 bits）
+
+        // sign bit placed to float32 bit31
+        uint32_t sign = (h & 0x8000U) << 16; // 0x8000 << 16 = 0x8000_0000
+        // exponent:（5 bits）
+        uint32_t exp = (h & 0x7C00U) >> 10; // 0x7C00 = 0111 1100 0000 (half exponent mask)
+        // mantissa（10 bits）
+        uint32_t mant = (h & 0x03FFU); // 10-bit fraction
+
+        // cases：Zero/Subnormal, Normal, Inf/NaN
+        if (exp == 0) {
+            // exp==0: Zero or Subnormal ----------
+            if (mant == 0) {
+                // ±0.0
+                // sign = either 0x00000000 or 0x80000000
+                return std::bit_cast<float>(sign);
+            } else {
+                // ---------- Subnormal ----------
+                // half subnormal:
+                //    value = (-1)^sign * (mant / 2^10) * 2^(1 - bias)
+                // half bias = 15 → exponent = 1 - 15 = -14
+                float f = (static_cast<float>(mant) / 1024.0F) * std::powf(2.0F, -14.0F);
+                return sign ? -f : f;
+            }
+        } else if (exp == 0x1F) {
+            // exp==31: Inf or NaN ----------
+            // float32:
+            //    exponent = 255 (0xFF)
+            //    mantissa = mant << 13
+            uint32_t f = sign | 0x7F800000U | (mant << 13);
+            return std::bit_cast<float>(f);
+        } else {
+            // Normalized ----------
+            // float32 exponent:
+            //   exp32 = exp16 - bias16 + bias32
+            //   bias16 = 15
+            //   bias32 = 127
+            //
+            // so: exp32 = exp + (127 - 15)
+            uint32_t f = sign | ((exp + (127 - 15)) << 23) // place to float32 exponent
+                         | (mant << 13);                   // mantissa align to 23 bits
+            return std::bit_cast<float>(f);
+        }
+    }
+};
+
 class UUIDVarBinaryConverter : public PhysicalToLogicalConverter {
 public:
     UUIDVarBinaryConverter(int type_length) : _type_length(type_length) {}

be/src/vec/exec/format/parquet/schema_desc.cpp

@@ -308,6 +308,8 @@ std::pair<DataTypePtr, bool> FieldDescriptor::convert_to_doris_type(
     } else if (logicalType.__isset.UUID) {
         ans.first =
                 DataTypeFactory::instance().create_data_type(TYPE_VARBINARY, nullable, -1, -1, 16);
+    } else if (logicalType.__isset.FLOAT16) {
+        ans.first = DataTypeFactory::instance().create_data_type(TYPE_FLOAT, nullable);
     } else {
         throw Exception(Status::InternalError("Not supported parquet logicalType"));
     }