Minor: pre allocate view vec

Author: lyang24

parquet/src/arrow/array_reader/byte_view_array.rs

@@ -162,13 +162,10 @@ impl ColumnValueDecoder for ByteViewArrayColumnValueDecoder {
             ));
         }
 
-        let mut buffer = ViewBuffer::default();
-        let mut decoder = ByteViewArrayDecoderPlain::new(
-            buf,
-            num_values as usize,
-            Some(num_values as usize),
-            self.validate_utf8,
-        );
+        let num_values = num_values as usize;
+        let mut buffer = ViewBuffer::with_capacity(num_values);
+        let mut decoder =
+            ByteViewArrayDecoderPlain::new(buf, num_values, Some(num_values), self.validate_utf8);
         decoder.read(&mut buffer, usize::MAX)?;
         self.dict = Some(buffer);
         Ok(())

parquet/src/arrow/buffer/view_buffer.rs

@@ -33,6 +33,14 @@ pub struct ViewBuffer {
 }
 
 impl ViewBuffer {
+    /// Create a new ViewBuffer with capacity for the specified number of views
+    pub fn with_capacity(capacity: usize) -> Self {
+        Self {
+            views: Vec::with_capacity(capacity),
+            buffers: Vec::new(),
+        }
+    }
+
     pub fn is_empty(&self) -> bool {
         self.views.is_empty()
     }