feat(spark): implement Spark try_avg function

datafusion/spark/src/function/aggregate/mod.rs

@@ -21,10 +21,16 @@ use std::sync::Arc;
 pub mod avg;
 pub mod try_sum;
 
+pub mod try_avg;
 pub mod expr_fn {
     use datafusion_functions::export_functions;
 
     export_functions!((avg, "Returns the average value of a given column", arg1));
+    export_functions!((
+        try_avg,
+        "Returns the avg of values for a column, or NULL if overflow occurs",
+        arg1
+    ));
     export_functions!((
         try_sum,
         "Returns the sum of values for a column, or NULL if overflow occurs",
@@ -40,6 +46,10 @@ pub fn try_sum() -> Arc<AggregateUDF> {
     Arc::new(AggregateUDF::new_from_impl(try_sum::SparkTrySum::new()))
 }
 
+pub fn try_avg() -> Arc<AggregateUDF> {
+    Arc::new(AggregateUDF::new_from_impl(try_avg::SparkTryAvg::new()))
+}
+
 pub fn functions() -> Vec<Arc<AggregateUDF>> {
-    vec![avg(), try_sum()]
+    vec![avg(), try_avg(), try_sum()]
 }