From bb98a1d0273f1710a0c25a461e803210f82ebd13 Mon Sep 17 00:00:00 2001
From: "Jorge C. Leitao" <jorgecarleitao@gmail.com>
Date: Thu, 9 Dec 2021 16:05:41 +0000
Subject: [PATCH] Improved performance.

---
 src/io/parquet/read/binary/basic.rs | 6 +++++-
 src/io/parquet/read/utils.rs        | 6 ++++--
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/io/parquet/read/binary/basic.rs b/src/io/parquet/read/binary/basic.rs
index 5d7d0ced562..96b5b21adb0 100644
--- a/src/io/parquet/read/binary/basic.rs
+++ b/src/io/parquet/read/binary/basic.rs
@@ -214,7 +214,7 @@ fn read_plain_optional<O: Offset>(
 
 pub(super) fn read_plain_required<O: Offset>(
     buffer: &[u8],
-    _length: usize,
+    additional: usize,
     offsets: &mut MutableBuffer<O>,
     values: &mut MutableBuffer<u8>,
 ) {
@@ -222,11 +222,15 @@ pub(super) fn read_plain_required<O: Offset>(
 
     let values_iterator = utils::BinaryIter::new(buffer);
 
+    // each value occupies 4 bytes + len declared in 4 bytes => reserve accordingly.
+    values.reserve(buffer.len() - 4 * additional);
+    let a = values.capacity();
     for value in values_iterator {
         last_offset += O::from_usize(value.len()).unwrap();
         values.extend_from_slice(value);
         offsets.push(last_offset);
     }
+    debug_assert_eq!(a, values.capacity());
 }
 
 pub(super) fn extend_from_page<O: Offset>(
diff --git a/src/io/parquet/read/utils.rs b/src/io/parquet/read/utils.rs
index 5659f2d6440..85b40a95a6b 100644
--- a/src/io/parquet/read/utils.rs
+++ b/src/io/parquet/read/utils.rs
@@ -1,4 +1,6 @@
-use parquet2::encoding::{get_length, Encoding};
+use std::convert::TryInto;
+
+use parquet2::encoding::Encoding;
 use parquet2::metadata::ColumnDescriptor;
 use parquet2::page::{split_buffer as _split_buffer, DataPage, DataPageHeader};
 
@@ -22,7 +24,7 @@ impl<'a> Iterator for BinaryIter<'a> {
         if self.values.is_empty() {
             return None;
         }
-        let length = get_length(self.values) as usize;
+        let length = u32::from_le_bytes(self.values[0..4].try_into().unwrap()) as usize;
         self.values = &self.values[4..];
         let result = &self.values[..length];
         self.values = &self.values[length..];