Add tracing debug/trace logging on schema cast failures

Add tracing statements to try_cast_to() that log schema information
and record batch contents when errors occur:
- debug! logs actual and expected schemas on any error
- trace! logs full record batch contents for detailed debugging

This helps diagnose schema mismatch issues during record batch casting.

Author: phillipleblanc

datafusion-federation/Cargo.toml

@@ -26,11 +26,11 @@ async-trait.workspace = true
 datafusion.workspace = true
 async-stream.workspace = true
 arrow-json.workspace = true
+tracing = "0.1"
 
 [dev-dependencies]
 tokio.workspace = true
 tracing-subscriber = { version = "0.3.18", features = ["env-filter"] }
-tracing = "0.1.40"
 insta = { version = "1.42.0", features = ["filters"] }
 
 [[example]]

datafusion-federation/src/schema_cast/record_convert.rs

@@ -52,6 +52,12 @@ pub fn try_cast_to(record_batch: RecordBatch, expected_schema: SchemaRef) -> Res
     let actual_schema = record_batch.schema();
 
     if actual_schema.fields().len() != expected_schema.fields().len() {
+        tracing::debug!(
+            actual_schema = ?actual_schema,
+            expected_schema = ?expected_schema,
+            "Schema mismatch in try_cast_to"
+        );
+        tracing::trace!(record_batch = ?record_batch, "Record batch contents");
         return Err(Error::UnexpectedNumberOfColumns {
             expected: expected_schema.fields().len(),
             found: actual_schema.fields().len(),
@@ -122,10 +128,26 @@ pub fn try_cast_to(record_batch: RecordBatch, expected_schema: SchemaRef) -> Res
                     .map_err(|e| Error::UnableToConvertRecordBatch { source: e }),
             }
         })
-        .collect::<Result<Vec<Arc<dyn Array>>>>()?;
+        .collect::<Result<Vec<Arc<dyn Array>>>>()
+        .map_err(|e| {
+            tracing::debug!(
+                actual_schema = ?actual_schema,
+                expected_schema = ?expected_schema,
+                "Cast error in try_cast_to"
+            );
+            tracing::trace!(record_batch = ?record_batch, "Record batch contents");
+            e
+        })?;
 
-    RecordBatch::try_new(expected_schema, cols)
-        .map_err(|e| Error::UnableToConvertRecordBatch { source: e })
+    RecordBatch::try_new(expected_schema.clone(), cols).map_err(|e| {
+        tracing::debug!(
+            actual_schema = ?actual_schema,
+            expected_schema = ?expected_schema,
+            "RecordBatch creation error in try_cast_to"
+        );
+        tracing::trace!(record_batch = ?record_batch, "Record batch contents");
+        Error::UnableToConvertRecordBatch { source: e }
+    })
 }
 
 #[cfg(test)]