perf: early stop if all values in arr are null

crates/core/src/kernel/snapshot/parse.rs

@@ -11,6 +11,11 @@ use crate::{DeltaResult, DeltaTableError};
 
 pub(super) fn read_metadata(batch: &dyn ProvidesColumnByName) -> DeltaResult<Option<Metadata>> {
     if let Some(arr) = ex::extract_and_cast_opt::<StructArray>(batch, "metaData") {
+        // Stop early if all values are null
+        if arr.null_count() == arr.len() {
+            return Ok(None);
+        }
+
         let id = ex::extract_and_cast::<StringArray>(arr, "id")?;
         let name = ex::extract_and_cast::<StringArray>(arr, "name")?;
         let description = ex::extract_and_cast::<StringArray>(arr, "description")?;
@@ -43,6 +48,11 @@ pub(super) fn read_metadata(batch: &dyn ProvidesColumnByName) -> DeltaResult<Opt
 
 pub(super) fn read_protocol(batch: &dyn ProvidesColumnByName) -> DeltaResult<Option<Protocol>> {
     if let Some(arr) = ex::extract_and_cast_opt::<StructArray>(batch, "protocol") {
+        // Stop early if all values are null
+        if arr.null_count() == arr.len() {
+            return Ok(None);
+        }
+
         let min_reader_version = ex::extract_and_cast::<Int32Array>(arr, "minReaderVersion")?;
         let min_writer_version = ex::extract_and_cast::<Int32Array>(arr, "minWriterVersion")?;
         let maybe_reader_features = ex::extract_and_cast_opt::<ListArray>(arr, "readerFeatures");
@@ -138,6 +148,11 @@ pub(super) fn read_cdf_adds(array: &dyn ProvidesColumnByName) -> DeltaResult<Vec
     let mut result = Vec::new();
 
     if let Some(arr) = ex::extract_and_cast_opt::<StructArray>(array, "cdc") {
+        // Stop early if all values are null
+        if arr.null_count() == arr.len() {
+            return Ok(result);
+        }
+
         let path = ex::extract_and_cast::<StringArray>(arr, "path")?;
         let pvs = ex::extract_and_cast_opt::<MapArray>(arr, "partitionValues");
         let size = ex::extract_and_cast::<Int64Array>(arr, "size")?;
@@ -171,6 +186,11 @@ pub(super) fn read_removes(array: &dyn ProvidesColumnByName) -> DeltaResult<Vec<
     let mut result = Vec::new();
 
     if let Some(arr) = ex::extract_and_cast_opt::<StructArray>(array, "remove") {
+        // Stop early if all values are null
+        if arr.null_count() == arr.len() {
+            return Ok(result);
+        }
+
         let path = ex::extract_and_cast::<StringArray>(arr, "path")?;
         let data_change = ex::extract_and_cast::<BooleanArray>(arr, "dataChange")?;
         let deletion_timestamp = ex::extract_and_cast::<Int64Array>(arr, "deletionTimestamp")?;