Added read Decimal from parquet

Cargo.toml

@@ -60,7 +60,7 @@ futures = { version = "0.3", optional = true }
 # for faster hashing
 ahash = { version = "0.7", optional = true }
 
-parquet2 = { version = "0.5", optional = true, default_features = false, features = ["stream"] }
+parquet2 = { git= "https://github.com/jorgecarleitao/parquet2.git", rev="e6bd6723c876c21667c74fb75db181d99d646bc2", optional = true, default_features = false, features = ["stream"] }
 
 avro-rs = { version = "0.13", optional = true, default_features = false }
 

parquet_integration/write_parquet.py

@@ -1,6 +1,7 @@
 import pyarrow as pa
 import pyarrow.parquet
 import os
+from decimal import Decimal
 
 PYARROW_PATH = "fixtures/pyarrow3"
 
@@ -11,6 +12,7 @@ def case_basic_nullable(size=1):
     string = ["Hello", None, "aa", "", None, "abc", None, None, "def", "aaa"]
     boolean = [True, None, False, False, None, True, None, None, True, True]
     string_large = ["ABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCDABCD😃🌚🕳👊"] * 10
+    decimal = [Decimal(e) if e is not None else None for e in int64]
 
     fields = [
         pa.field("int64", pa.int64()),
@@ -20,6 +22,10 @@ def case_basic_nullable(size=1):
         pa.field("date", pa.timestamp("ms")),
         pa.field("uint32", pa.uint32()),
         pa.field("string_large", pa.utf8()),
+        # decimal testing
+        pa.field("decimal_9", pa.decimal128(9,0)),
+        pa.field("decimal_18", pa.decimal128(18,0)),
+        pa.field("decimal_26", pa.decimal128(26,0)),
     ]
     schema = pa.schema(fields)
 
@@ -32,6 +38,9 @@ def case_basic_nullable(size=1):
             "date": int64 * size,
             "uint32": int64 * size,
             "string_large": string_large * size,
+            "decimal_9": decimal * size,
+            "decimal_18": decimal * size,
+            "decimal_26": decimal * size,
         },
         schema,
         f"basic_nullable_{size*10}.parquet",
@@ -43,6 +52,7 @@ def case_basic_required(size=1):
     float64 = [0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]
     string = ["Hello", "bbb", "aa", "", "bbb", "abc", "bbb", "bbb", "def", "aaa"]
     boolean = [True, True, False, False, False, True, True, True, True, True]
+    decimal = [Decimal(e) for e in int64]
 
     fields = [
         pa.field("int64", pa.int64(), nullable=False),
@@ -57,6 +67,9 @@ def case_basic_required(size=1):
             nullable=False,
         ),
         pa.field("uint32", pa.uint32(), nullable=False),
+        pa.field("decimal_9", pa.decimal128(9,0), nullable=False),
+        pa.field("decimal_18", pa.decimal128(18,0), nullable=False),
+        pa.field("decimal_26", pa.decimal128(26,0), nullable=False),
     ]
     schema = pa.schema(fields)
 
@@ -68,6 +81,9 @@ def case_basic_required(size=1):
             "bool": boolean * size,
             "date": int64 * size,
             "uint32": int64 * size,
+            "decimal_9": decimal * size,
+            "decimal_18": decimal * size,
+            "decimal_26": decimal * size,
         },
         schema,
         f"basic_required_{size*10}.parquet",

src/io/parquet/read/mod.rs

@@ -1,8 +1,5 @@
 //! APIs to read from Parquet format.
-use std::{
-    io::{Read, Seek},
-    sync::Arc,
-};
+use std::{convert::TryInto, io::{Read, Seek}, sync::Arc};
 
 use futures::{AsyncRead, AsyncSeek, Stream};
 pub use parquet2::{
@@ -21,11 +18,7 @@ pub use parquet2::{
     types::int96_to_i64_ns,
 };
 
-use crate::{
-    array::{Array, DictionaryKey},
-    datatypes::{DataType, IntervalUnit, TimeUnit},
-    error::{ArrowError, Result},
-};
+use crate::{array::{Array, DictionaryKey, PrimitiveArray}, datatypes::{DataType, IntervalUnit, TimeUnit}, error::{ArrowError, Result}};
 
 mod binary;
 mod boolean;
@@ -211,7 +204,47 @@ pub fn page_iter_to_array<
         FixedSizeBinary(_) => Ok(Box::new(fixed_size_binary::iter_to_array(
             iter, data_type, metadata,
         )?)),
-
+        Decimal(_, _) => match metadata.descriptor().type_() {
+            ParquetType::PrimitiveType { physical_type, ..} => match physical_type{
+                PhysicalType::Int32 => primitive::iter_to_array(
+                    iter,
+                    metadata,
+                    data_type,
+                    |x: i32| x as i128,
+                ),
+                PhysicalType::Int64 => primitive::iter_to_array(
+                    iter,
+                    metadata,
+                    data_type,
+                    |x: i64| x as i128,
+                ),
+                PhysicalType::FixedLenByteArray(n) => {
+                    if *n > 16 {
+                        Err(ArrowError::NotYetImplemented(format!(
+                            "Can't decode Decimal128 type from Fixed Size Byte Array of len {:?}",
+                            n
+                        )))
+                    } else {
+                        let paddings = (0..(16-*n)).map(|_| 0u8).collect::<Vec<_>>();
+                        fixed_size_binary::iter_to_array(iter, DataType::FixedSizeBinary(*n), metadata)
+                        .map(|e|{
+                            let a = e.into_iter().map(|v| 
+                                    v.and_then(|v1| {
+                                        [&paddings, v1].concat().try_into().map(
+                                            |pad16| i128::from_be_bytes(pad16)
+                                        ).ok()   
+                                    }
+                                )
+                            ).collect::<Vec<_>>();
+                            Box::new(PrimitiveArray::<i128>::from(a).to(data_type)) as Box<dyn Array>
+                        }
+                        )
+                    }
+                },
+                _ => unreachable!()
+            },
+            _ => unreachable!()
+        },
         List(ref inner) => match inner.data_type() {
             UInt8 => primitive::iter_to_array_nested(iter, metadata, data_type, |x: i32| x as u8),
             UInt16 => primitive::iter_to_array_nested(iter, metadata, data_type, |x: i32| x as u16),

src/io/parquet/read/schema/convert.rs

@@ -167,6 +167,9 @@ pub fn from_int64(
             ParquetTimeUnit::MICROS(_) => DataType::Time64(TimeUnit::Microsecond),
             ParquetTimeUnit::NANOS(_) => DataType::Time64(TimeUnit::Nanosecond),
         },
+        (Some(PrimitiveConvertedType::Decimal(precision,scale)), _) => {
+            DataType::Decimal(*precision as usize, *scale as usize)
+        }
         (c, l) => {
             return Err(ArrowError::NotYetImplemented(format!(
                 "The conversion of (Int64, {:?}, {:?}) to arrow still not implemented",

src/io/parquet/read/schema/metadata.rs

@@ -120,7 +120,10 @@ mod tests {
                 "bool",
                 "date",
                 "uint32",
-                "string_large"
+                "string_large",
+                "decimal_9",
+                "decimal_18",
+                "decimal_26"
             ]
         );
         Ok(())

src/io/parquet/read/statistics/fixlen.rs

@@ -0,0 +1,105 @@
+use std::convert::{TryFrom, TryInto};
+
+use super::super::schema;
+use super::primitive::PrimitiveStatistics;
+use crate::datatypes::DataType;
+use crate::error::{ArrowError, Result};
+use parquet2::schema::types::ParquetType;
+use parquet2::{
+    schema::types::PhysicalType,
+    statistics::{
+        FixedLenStatistics as ParquetFixedLenStatistics, Statistics as ParquetStatistics,
+    },
+};
+
+use super::Statistics;
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct FixedLenStatistics {
+    pub null_count: Option<i64>,
+    pub distinct_count: Option<i64>,
+    pub min_value: Option<Vec<u8>>,
+    pub max_value: Option<Vec<u8>>,
+    pub data_type: DataType,
+}
+
+impl Statistics for FixedLenStatistics {
+    fn data_type(&self) -> &DataType {
+        &self.data_type
+    }
+}
+
+impl From<&ParquetFixedLenStatistics> for FixedLenStatistics {
+    fn from(stats: &ParquetFixedLenStatistics) -> Self {
+        let byte_lens = match stats.physical_type() {
+            PhysicalType::FixedLenByteArray(size) => *size,
+            _ => unreachable!(),
+        };
+        Self {
+            null_count: stats.null_count,
+            distinct_count: stats.distinct_count,
+            min_value: stats.min_value.clone(),
+            max_value: stats.max_value.clone(),
+            data_type: DataType::FixedSizeBinary(byte_lens),
+        }
+    }
+}
+
+impl TryFrom<(&ParquetFixedLenStatistics, DataType)> for PrimitiveStatistics<i128> {
+    type Error = ArrowError;
+    fn try_from((stats, data_type): (&ParquetFixedLenStatistics, DataType)) -> Result<Self> {
+        let byte_lens = match stats.physical_type() {
+            PhysicalType::FixedLenByteArray(size) => *size,
+            _ => unreachable!(),
+        };
+        if byte_lens > 16 {
+            Err(ArrowError::Other(format!(
+                "Can't deserialize i128 from Fixed Len Byte array with lengtg {:?}",
+                byte_lens
+            )))
+        } else {
+            let paddings = (0..(16 - byte_lens)).map(|_| 0u8).collect::<Vec<_>>();
+            let max_value = stats.max_value.as_ref().and_then(|value| {
+                [paddings.as_slice(), value]
+                    .concat()
+                    .try_into()
+                    .map(|v| i128::from_be_bytes(v))
+                    .ok()
+            });
+
+            let min_value = stats.min_value.as_ref().and_then(|value| {
+                [paddings.as_slice(), value]
+                    .concat()
+                    .try_into()
+                    .map(|v| i128::from_be_bytes(v))
+                    .ok()
+            });
+            Ok(Self {
+                data_type,
+                null_count: stats.null_count,
+                distinct_count: stats.distinct_count,
+                max_value,
+                min_value,
+            })
+        }
+    }
+}
+
+pub(super) fn statistics_from_fix_len(
+    stats: &ParquetFixedLenStatistics,
+    type_: &ParquetType,
+) -> Result<Box<dyn Statistics>> {
+    let data_type = schema::to_data_type(type_)?.unwrap();
+
+    use DataType::*;
+    Ok(match data_type {
+        Decimal(_, _) => Box::new(PrimitiveStatistics::<i128>::try_from((stats, data_type))?),
+        FixedSizeBinary(_) => Box::new(FixedLenStatistics::from(stats)),
+        other => {
+            return Err(ArrowError::NotYetImplemented(format!(
+                "Can't read {:?} from parquet",
+                other
+            )))
+        }
+    })
+}

src/io/parquet/read/statistics/mod.rs

@@ -13,6 +13,8 @@ mod binary;
 pub use binary::*;
 mod boolean;
 pub use boolean::*;
+mod fixlen;
+pub use fixlen::*;
 
 /// Trait representing a deserialized parquet statistics into arrow.
 pub trait Statistics: std::fmt::Debug {
@@ -70,6 +72,10 @@ pub fn deserialize_statistics(stats: &dyn ParquetStatistics) -> Result<Box<dyn S
                 DataType::Float64,
             ))))
         }
+        PhysicalType::FixedLenByteArray(_) =>{
+            let stats = stats.as_any().downcast_ref().unwrap();
+            fixlen::statistics_from_fix_len(stats, stats.descriptor.type_())
+        }
         _ => Err(ArrowError::NotYetImplemented(
             "Reading Fixed-len array statistics is not yet supported".to_string(),
         )),

src/io/parquet/read/statistics/primitive.rs

@@ -54,6 +54,7 @@ pub(super) fn statistics_from_i32(
         UInt32 => Box::new(PrimitiveStatistics::<u32>::from((stats, data_type))),
         Int8 => Box::new(PrimitiveStatistics::<i8>::from((stats, data_type))),
         Int16 => Box::new(PrimitiveStatistics::<i16>::from((stats, data_type))),
+        Decimal(_, _) => Box::new(PrimitiveStatistics::<i128>::from((stats, data_type))),
         _ => Box::new(PrimitiveStatistics::<i32>::from((stats, data_type))),
     })
 }
@@ -69,6 +70,7 @@ pub(super) fn statistics_from_i64(
         UInt64 => {
             Box::new(PrimitiveStatistics::<u64>::from((stats, data_type))) as Box<dyn Statistics>
         }
+        Decimal(_, _) => Box::new(PrimitiveStatistics::<i128>::from((stats, data_type))),
         _ => Box::new(PrimitiveStatistics::<i64>::from((stats, data_type))),
     })
 }

src/io/parquet/write/fixed_len_bytes.rs

@@ -1,9 +1,13 @@
 use parquet2::{
-    compression::create_codec, encoding::Encoding, metadata::ColumnDescriptor,
-    page::CompressedDataPage, write::WriteOptions,
+    compression::create_codec,
+    encoding::Encoding,
+    metadata::ColumnDescriptor,
+    page::CompressedDataPage,
+    statistics::{serialize_statistics, deserialize_statistics, ParquetStatistics},
+    write::WriteOptions,
 };
 
-use super::utils;
+use super::{binary::ord_binary, utils};
 use crate::{
     array::{Array, FixedSizeBinaryArray},
     error::Result,
@@ -54,16 +58,47 @@ pub fn array_to_page(
         buffer
     };
 
+    let statistics = if options.write_statistics {
+        build_statistics(array, descriptor.clone())
+    } else {
+        None
+    };
+
     utils::build_plain_page(
         buffer,
         array.len(),
         array.null_count(),
         uncompressed_page_size,
         0,
         definition_levels_byte_length,
-        None,
+        statistics,
         descriptor,
         options,
         Encoding::Plain,
     )
 }
+
+pub(super) fn build_statistics(
+    array: &FixedSizeBinaryArray,
+    descriptor: ColumnDescriptor,
+) -> Option<ParquetStatistics> {
+    let pq_statistics = &ParquetStatistics {
+        max: None,
+        min: None,
+        null_count: Some(array.null_count() as i64),
+        distinct_count: None,
+        max_value: array
+            .iter()
+            .flatten()
+            .max_by(|x, y| ord_binary(x, y))
+            .map(|x| x.to_vec()),
+        min_value: array
+            .iter()
+            .flatten()
+            .min_by(|x, y| ord_binary(x, y))
+            .map(|x| x.to_vec()),
+    };
+    deserialize_statistics(pq_statistics,descriptor).map(
+        |e| serialize_statistics(&*e)
+    ).ok()
+}