Add Append Column API (#4155)

parquet/src/arrow/arrow_writer/byte_array.rs

@@ -104,12 +104,12 @@ impl<'a> ByteArrayWriter<'a> {
     /// Returns a new [`ByteArrayWriter`]
     pub fn new(
         descr: ColumnDescPtr,
-        props: &'a WriterPropertiesPtr,
+        props: WriterPropertiesPtr,
         page_writer: Box<dyn PageWriter + 'a>,
         on_close: OnCloseColumnChunk<'a>,
     ) -> Result<Self> {
         Ok(Self {
-            writer: GenericColumnWriter::new(descr, props.clone(), page_writer),
+            writer: GenericColumnWriter::new(descr, props, page_writer),
             on_close: Some(on_close),
         })
     }

parquet/src/file/writer.rs

@@ -21,7 +21,7 @@
 use crate::bloom_filter::Sbbf;
 use crate::format as parquet;
 use crate::format::{ColumnIndex, OffsetIndex, RowGroup};
-use std::io::{BufWriter, IoSlice};
+use std::io::{BufWriter, IoSlice, Read};
 use std::{io::Write, sync::Arc};
 use thrift::protocol::{TCompactOutputProtocol, TSerializable};
 
@@ -35,6 +35,7 @@ use crate::column::{
 };
 use crate::data_type::DataType;
 use crate::errors::{ParquetError, Result};
+use crate::file::reader::ChunkReader;
 use crate::file::{
     metadata::*, properties::WriterPropertiesPtr,
     statistics::to_thrift as statistics_to_thrift, PARQUET_MAGIC,
@@ -423,27 +424,15 @@ impl<'a, W: Write> SerializedRowGroupWriter<'a, W> {
         }
     }
 
-    /// Returns the next column writer, if available, using the factory function;
-    /// otherwise returns `None`.
-    pub(crate) fn next_column_with_factory<'b, F, C>(
-        &'b mut self,
-        factory: F,
-    ) -> Result<Option<C>>
-    where
-        F: FnOnce(
-            ColumnDescPtr,
-            &'b WriterPropertiesPtr,
-            Box<dyn PageWriter + 'b>,
-            OnCloseColumnChunk<'b>,
-        ) -> Result<C>,
-    {
-        self.assert_previous_writer_closed()?;
-
-        if self.column_index >= self.descr.num_columns() {
-            return Ok(None);
-        }
-        let page_writer = Box::new(SerializedPageWriter::new(self.buf));
+    /// Advance `self.column_index` returning the next [`ColumnDescPtr`] if any
+    fn next_column_desc(&mut self) -> Option<ColumnDescPtr> {
+        let ret = self.descr.columns().get(self.column_index)?.clone();
+        self.column_index += 1;
+        Some(ret)
+    }
 
+    /// Returns [`OnCloseColumnChunk`] for the next writer
+    fn get_on_close(&mut self) -> (&mut TrackedWrite<W>, OnCloseColumnChunk<'_>) {
         let total_bytes_written = &mut self.total_bytes_written;
         let total_uncompressed_bytes = &mut self.total_uncompressed_bytes;
         let total_rows_written = &mut self.total_rows_written;
@@ -475,28 +464,115 @@ impl<'a, W: Write> SerializedRowGroupWriter<'a, W> {
 
             Ok(())
         };
+        (self.buf, Box::new(on_close))
+    }
 
-        let column = self.descr.column(self.column_index);
-        self.column_index += 1;
-
-        Ok(Some(factory(
-            column,
-            &self.props,
-            page_writer,
-            Box::new(on_close),
-        )?))
+    /// Returns the next column writer, if available, using the factory function;
+    /// otherwise returns `None`.
+    pub(crate) fn next_column_with_factory<'b, F, C>(
+        &'b mut self,
+        factory: F,
+    ) -> Result<Option<C>>
+    where
+        F: FnOnce(
+            ColumnDescPtr,
+            WriterPropertiesPtr,
+            Box<dyn PageWriter + 'b>,
+            OnCloseColumnChunk<'b>,
+        ) -> Result<C>,
+    {
+        self.assert_previous_writer_closed()?;
+        Ok(match self.next_column_desc() {
+            Some(column) => {
+                let props = self.props.clone();
+                let (buf, on_close) = self.get_on_close();
+                let page_writer = Box::new(SerializedPageWriter::new(buf));
+                Some(factory(column, props, page_writer, Box::new(on_close))?)
+            }
+            None => None,
+        })
     }
 
     /// Returns the next column writer, if available; otherwise returns `None`.
     /// In case of any IO error or Thrift error, or if row group writer has already been
     /// closed returns `Err`.
     pub fn next_column(&mut self) -> Result<Option<SerializedColumnWriter<'_>>> {
         self.next_column_with_factory(|descr, props, page_writer, on_close| {
-            let column_writer = get_column_writer(descr, props.clone(), page_writer);
+            let column_writer = get_column_writer(descr, props, page_writer);
             Ok(SerializedColumnWriter::new(column_writer, Some(on_close)))
         })
     }
 
+    /// Append an encoded column chunk from another source without decoding it
+    ///
+    /// This can be used for efficiently concatenating or projecting parquet data,
+    /// or encoding parquet data to temporary in-memory buffers
+    ///
+    /// See [`Self::next_column`] for writing data that isn't already encoded
+    pub fn append_column<R: ChunkReader>(
+        &mut self,
+        reader: &R,
+        mut close: ColumnCloseResult,
+    ) -> Result<()> {
+        self.assert_previous_writer_closed()?;
+        let desc = self.next_column_desc().ok_or_else(|| {
+            general_err!("exhausted columns in SerializedRowGroupWriter")
+        })?;
+
+        let metadata = close.metadata;
+
+        if metadata.column_descr() != desc.as_ref() {
+            return Err(general_err!(
+                "column descriptor mismatch, expected {:?} got {:?}",
+                desc,
+                metadata.column_descr()
+            ));
+        }
+
+        let src_dictionary_offset = metadata.dictionary_page_offset();
+        let src_data_offset = metadata.data_page_offset();
+        let src_offset = src_dictionary_offset.unwrap_or(src_data_offset);
+        let src_length = metadata.compressed_size();
+
+        let write_offset = self.buf.bytes_written();
+        let mut read = reader.get_read(src_offset as _)?.take(src_length as _);
+        let write_length = std::io::copy(&mut read, &mut self.buf)?;
+
+        if src_length as u64 != write_length {
+            return Err(general_err!(
+                "Failed to splice column data, expected {read_length} got {write_length}"
+            ));
+        }
+
+        let file_offset = self.buf.bytes_written() as i64;
+
+        let map_offset = |x| x - src_offset + write_offset as i64;
+        let mut builder = ColumnChunkMetaData::builder(metadata.column_descr_ptr())
+            .set_compression(metadata.compression())
+            .set_encodings(metadata.encodings().clone())
+            .set_file_offset(file_offset)
+            .set_total_compressed_size(metadata.compressed_size())
+            .set_total_uncompressed_size(metadata.uncompressed_size())
+            .set_num_values(metadata.num_values())
+            .set_data_page_offset(map_offset(src_data_offset))
+            .set_dictionary_page_offset(src_dictionary_offset.map(map_offset));
+
+        if let Some(statistics) = metadata.statistics() {
+            builder = builder.set_statistics(statistics.clone())
+        }
+        close.metadata = builder.build()?;
+
+        if let Some(offsets) = close.offset_index.as_mut() {
+            for location in &mut offsets.page_locations {
+                location.offset = map_offset(location.offset)
+            }
+        }
+
+        SerializedPageWriter::new(self.buf).write_metadata(&metadata)?;
+        let (_, on_close) = self.get_on_close();
+        on_close(close)
+    }
+
     /// Closes this row group writer and returns row group metadata.
     pub fn close(mut self) -> Result<RowGroupMetaDataPtr> {
         if self.row_group_metadata.is_none() {
@@ -516,9 +592,9 @@ impl<'a, W: Write> SerializedRowGroupWriter<'a, W> {
             if let Some(on_close) = self.on_close.take() {
                 on_close(
                     metadata,
-                    self.bloom_filters.clone(),
-                    self.column_indexes.clone(),
-                    self.offset_indexes.clone(),
+                    self.bloom_filters,
+                    self.column_indexes,
+                    self.offset_indexes,
                 )?
             }
         }
@@ -720,9 +796,11 @@ mod tests {
 
     use crate::basic::{Compression, Encoding, LogicalType, Repetition, Type};
     use crate::column::page::PageReader;
+    use crate::column::reader::get_typed_column_reader;
     use crate::compression::{create_codec, Codec, CodecOptionsBuilder};
     use crate::data_type::{BoolType, Int32Type};
     use crate::file::reader::ChunkReader;
+    use crate::file::serialized_reader::ReadOptionsBuilder;
     use crate::file::{
         properties::{ReaderProperties, WriterProperties, WriterVersion},
         reader::{FileReader, SerializedFileReader, SerializedPageReader},
@@ -1540,4 +1618,91 @@ mod tests {
         assert_eq!(s.min_value.as_deref(), Some(1_i32.to_le_bytes().as_ref()));
         assert_eq!(s.max_value.as_deref(), Some(3_i32.to_le_bytes().as_ref()));
     }
+
+    #[test]
+    fn test_spliced_write() {
+        let message_type = "
+            message test_schema {
+                REQUIRED INT32 i32 (INTEGER(32,true));
+                REQUIRED INT32 u32 (INTEGER(32,false));
+            }
+        ";
+        let schema = Arc::new(parse_message_type(message_type).unwrap());
+        let props = Arc::new(WriterProperties::builder().build());
+
+        let mut file = Vec::with_capacity(1024);
+        let mut file_writer =
+            SerializedFileWriter::new(&mut file, schema, props.clone()).unwrap();
+
+        let columns = file_writer.descr.columns();
+        let mut column_state: Vec<(_, Option<ColumnCloseResult>)> = columns
+            .iter()
+            .map(|_| (TrackedWrite::new(Vec::with_capacity(1024)), None))
+            .collect();
+
+        let mut column_state_slice = column_state.as_mut_slice();
+        let mut column_writers = Vec::with_capacity(columns.len());
+        for c in columns {
+            let ((buf, out), tail) = column_state_slice.split_first_mut().unwrap();
+            column_state_slice = tail;
+
+            let page_writer = Box::new(SerializedPageWriter::new(buf));
+            let col_writer = get_column_writer(c.clone(), props.clone(), page_writer);
+            column_writers.push(SerializedColumnWriter::new(
+                col_writer,
+                Some(Box::new(|on_close| {
+                    *out = Some(on_close);
+                    Ok(())
+                })),
+            ));
+        }
+
+        let column_data = [[1, 2, 3, 4], [7, 3, 7, 3]];
+
+        // Interleaved writing to the column writers
+        for (writer, batch) in column_writers.iter_mut().zip(column_data) {
+            let writer = writer.typed::<Int32Type>();
+            writer.write_batch(&batch, None, None).unwrap();
+        }
+
+        // Close the column writers
+        for writer in column_writers {
+            writer.close().unwrap()
+        }
+
+        // Splice column data into a row group
+        let mut row_group_writer = file_writer.next_row_group().unwrap();
+        for (write, close) in column_state {
+            let buf = Bytes::from(write.into_inner().unwrap());
+            row_group_writer
+                .append_column(&buf, close.unwrap())
+                .unwrap();
+        }
+        row_group_writer.close().unwrap();
+        file_writer.close().unwrap();
+
+        // Check data was written correctly
+        let file = Bytes::from(file);
+        let test_read = |reader: SerializedFileReader<Bytes>| {
+            let row_group = reader.get_row_group(0).unwrap();
+
+            let mut out = [0; 4];
+            let c1 = row_group.get_column_reader(0).unwrap();
+            let mut c1 = get_typed_column_reader::<Int32Type>(c1);
+            c1.read_batch(4, None, None, &mut out).unwrap();
+            assert_eq!(out, column_data[0]);
+
+            let c2 = row_group.get_column_reader(1).unwrap();
+            let mut c2 = get_typed_column_reader::<Int32Type>(c2);
+            c2.read_batch(4, None, None, &mut out).unwrap();
+            assert_eq!(out, column_data[1]);
+        };
+
+        let reader = SerializedFileReader::new(file.clone()).unwrap();
+        test_read(reader);
+
+        let options = ReadOptionsBuilder::new().with_page_index().build();
+        let reader = SerializedFileReader::new_with_options(file, options).unwrap();
+        test_read(reader);
+    }
 }