chore

Author: Weijun-H

arrow-json/benches/reader.rs

@@ -34,6 +34,7 @@ fn bench_decode_schema(
     data: &[u8],
     schema: Arc<Schema>,
     rows: usize,
+    projection: bool,
 ) {
     let mut group = c.benchmark_group(name);
     group.throughput(Throughput::Bytes(data.len() as u64));
@@ -45,6 +46,7 @@ fn bench_decode_schema(
         b.iter(|| {
             let mut decoder = ReaderBuilder::new(schema.clone())
                 .with_batch_size(rows)
+                .with_projection(projection)
                 .build_decoder()
                 .unwrap();
 
@@ -101,6 +103,7 @@ fn criterion_benchmark(c: &mut Criterion) {
         &wide_projection_data,
         full_schema,
         WIDE_PROJECTION_ROWS,
+        false,
     );
 
     // Projected schema: only 3 fields (f0, f10, f50) out of 100
@@ -115,6 +118,7 @@ fn criterion_benchmark(c: &mut Criterion) {
         &wide_projection_data,
         projected_schema,
         WIDE_PROJECTION_ROWS,
+        true,
     );
 }
 

arrow-json/src/reader/tape.rs

@@ -518,20 +518,24 @@ impl TapeDecoder {
                                         ))
                                     })?;
 
-                                if !projection.contains(field_name) {
-                                    if self.strict_mode {
+                                match (projection.contains(field_name), self.strict_mode) {
+                                    (true, _) => {}
+                                    (false, true) => {
                                         return Err(ArrowError::JsonError(format!(
                                             "column '{field_name}' missing from schema"
                                         )));
                                     }
-                                    // Field not in projection: skip its value
-                                    // Remove field name from tape (must have paired field_name:value)
-                                    self.elements.pop();
-                                    self.bytes.truncate(start);
-                                    self.offsets.pop();
-
-                                    // Replace Value state with SkipValue
-                                    *self.stack.last_mut().unwrap() = DecoderState::SkipValue(0);
+                                    (false, false) => {
+                                        // Field not in projection: skip its value
+                                        // Remove field name from tape (must have paired field_name:value)
+                                        self.elements.pop();
+                                        self.bytes.truncate(start);
+                                        self.offsets.pop();
+
+                                        // Replace Value state with SkipValue
+                                        *self.stack.last_mut().unwrap() =
+                                            DecoderState::SkipValue(0);
+                                    }
                                 }
                             }
                         }