use different buffer for different encoding

parquet/src/arrow/array_reader/byte_view_array.rs

@@ -327,6 +327,7 @@ impl ByteViewArrayDecoderPlain {
         let mut read = 0;
 
         let buf = self.buf.as_ref();
+        output.add_buffer(self.buf.clone());
         while self.offset < self.buf.len() && read != to_read {
             if self.offset + 4 > buf.len() {
                 return Err(ParquetError::EOF("eof decoding byte view array".into()));
@@ -340,7 +341,7 @@ impl ByteViewArrayDecoderPlain {
                 return Err(ParquetError::EOF("eof decoding byte view array".into()));
             }
 
-            output.try_push(&buf[start_offset..end_offset], self.validate_utf8)?;
+            output.try_push_with_offset(start_offset, end_offset)?;
 
             self.offset = end_offset;
             read += 1;
@@ -416,12 +417,10 @@ impl ByteViewArrayDecoderDeltaLength {
         }
 
         let mut start_offset = self.data_offset;
+        output.add_buffer(self.data.clone());
         for length in src_lengths {
             let end_offset = start_offset + *length as usize;
-            output.try_push(
-                &self.data.as_ref()[start_offset..end_offset],
-                self.validate_utf8,
-            )?;
+            output.try_push_with_offset(start_offset, end_offset)?;
             start_offset = end_offset;
         }
 
@@ -499,7 +498,7 @@ impl ByteViewArrayDecoderDictionary {
         }
 
         self.decoder.read(len, |keys| {
-            output.extend_from_dictionary(keys, &dict.views, &dict.buffer)
+            output.extend_from_dictionary(keys, &dict.views, dict.plain_buffer.as_ref().unwrap())
         })
     }
 

parquet/src/arrow/buffer/view_buffer.rs

@@ -22,13 +22,22 @@ use arrow_array::{make_array, ArrayRef};
 use arrow_buffer::{ArrowNativeType, Buffer, ToByteSlice};
 use arrow_data::{ArrayDataBuilder, ByteView};
 use arrow_schema::DataType as ArrowType;
+use bytes::Bytes;
 
 /// A buffer of variable-sized byte arrays that can be converted into
 /// a corresponding [`ArrayRef`]
 #[derive(Debug, Default)]
 pub struct ViewBuffer {
     pub views: Vec<u128>,
-    pub buffer: Vec<u8>,
+    /// If encoding in (`PLAIN`, `DELTA_LENGTH_BYTE_ARRAY`), we use `plain_buffer`
+    /// to hold the page data without copy.
+    pub plain_buffer: Option<Bytes>,
+    /// If encoding is `DELTA_BYTE_ARRAY`, we use `delta_buffer` to build data buffer
+    /// since this encoding's page data not hold full data.
+    ///
+    /// If encoding in (`PLAIN_DICTIONARY`, `RLE_DICTIONARY`), we need these two buffers
+    /// cause these encoding first build dict then use dict to read data.
+    pub delta_buffer: Vec<u8>,
 }
 
 impl ViewBuffer {
@@ -41,6 +50,36 @@ impl ViewBuffer {
         self.len() == 0
     }
 
+    /// add entire page buf to [`ViewBuffer`], avoid copy data.
+    pub fn add_buffer(&mut self, buf: Bytes) {
+        if self.plain_buffer.is_none() {
+            self.plain_buffer = Some(buf);
+        }
+    }
+
+    /// Push data to [`ViewBuffer`], since we already hold full data through [`Self::add_buffer`],
+    /// we only need to slice the data to build the view.
+    pub fn try_push_with_offset(&mut self, start_offset: usize, end_offset: usize) -> Result<()> {
+        let data = &self.plain_buffer.as_ref().unwrap()[start_offset..end_offset];
+        let length: u32 = (end_offset - start_offset) as u32;
+        if length <= 12 {
+            let mut view_buffer = [0; 16];
+            view_buffer[0..4].copy_from_slice(&length.to_le_bytes());
+            view_buffer[4..4 + length as usize].copy_from_slice(data);
+            self.views.push(u128::from_le_bytes(view_buffer));
+            return Ok(());
+        }
+
+        let view = ByteView {
+            length,
+            prefix: u32::from_le_bytes(data[0..4].try_into().unwrap()),
+            buffer_index: 0,
+            offset: start_offset as u32,
+        };
+        self.views.push(view.into());
+        Ok(())
+    }
+
     /// If `validate_utf8` this verifies that the first character of `data` is
     /// the start of a UTF-8 codepoint
     ///
@@ -68,8 +107,8 @@ impl ViewBuffer {
             return Ok(());
         }
 
-        let offset = self.buffer.len() as u32;
-        self.buffer.extend_from_slice(data);
+        let offset = self.delta_buffer.len() as u32;
+        self.delta_buffer.extend_from_slice(data);
 
         let view = ByteView {
             length,
@@ -129,20 +168,34 @@ impl ViewBuffer {
             return Ok(());
         }
         let first_buffer_offset = ((*first_buffer.unwrap()) >> 96) as u32 as usize;
-        match std::str::from_utf8(&self.buffer[first_buffer_offset..]) {
-            Ok(_) => Ok(()),
-            Err(e) => Err(general_err!("encountered non UTF-8 data: {}", e)),
+        if self.plain_buffer.is_none() {
+            match std::str::from_utf8(&self.delta_buffer[first_buffer_offset..]) {
+                Ok(_) => Ok(()),
+                Err(e) => Err(general_err!("encountered non UTF-8 data: {}", e)),
+            }
+        } else {
+            match std::str::from_utf8(&self.plain_buffer.as_ref().unwrap()[first_buffer_offset..]) {
+                Ok(_) => Ok(()),
+                Err(e) => Err(general_err!("encountered non UTF-8 data: {}", e)),
+            }
         }
     }
 
     /// Converts this into an [`ArrayRef`] with the provided `data_type` and `null_buffer`
     pub fn into_array(self, null_buffer: Option<Buffer>, data_type: ArrowType) -> ArrayRef {
         let len = self.len();
-        let array_data_builder = ArrayDataBuilder::new(data_type)
-            .len(len)
-            .add_buffer(Buffer::from_vec(self.views))
-            .add_buffer(Buffer::from_vec(self.buffer))
-            .null_bit_buffer(null_buffer);
+        let array_data_builder = {
+            let builder = ArrayDataBuilder::new(data_type)
+                .len(len)
+                .add_buffer(Buffer::from_vec(self.views))
+                .null_bit_buffer(null_buffer);
+
+            if self.plain_buffer.is_none() {
+                builder.add_buffer(Buffer::from_vec(self.delta_buffer))
+            } else {
+                builder.add_buffer(self.plain_buffer.unwrap().into())
+            }
+        };
 
         let data = match cfg!(debug_assertions) {
             true => array_data_builder.build().unwrap(),