Error if special numeric during copy to (#97)

Do not allow copying numeric nan and +-infinity.

src/pgrx_tests/copy_type_roundtrip.rs

@@ -987,6 +987,22 @@ mod tests {
         test_table.assert_expected_and_result_rows();
     }
 
+    #[pg_test]
+    #[should_panic = "Special numeric values like NaN, Inf, -Inf are not allowed"]
+    fn test_numeric_nan() {
+        let test_table = TestTable::<AnyNumeric>::new("numeric".into());
+        test_table.insert("INSERT INTO test_expected (a) VALUES ('NaN');");
+        test_table.assert_expected_and_result_rows();
+    }
+
+    #[pg_test]
+    #[should_panic = "Special numeric values like NaN, Inf, -Inf are not allowed"]
+    fn test_numeric_inf() {
+        let test_table = TestTable::<AnyNumeric>::new("numeric".into());
+        test_table.insert("INSERT INTO test_expected (a) VALUES ('-Infinity');");
+        test_table.assert_expected_and_result_rows();
+    }
+
     #[pg_test]
     fn test_geometry() {
         // Skip the test if postgis extension is not available

src/type_compat/pg_arrow_type_conversions.rs

@@ -173,7 +173,23 @@ pub(crate) fn i64_to_timetz(i64_timetz: i64) -> TimeWithTimeZone {
         .unwrap_or_else(|e| panic!("{}", e))
 }
 
+fn error_if_special_numeric(numeric: AnyNumeric) {
+    if ["NaN", "Infinity", "-Infinity"]
+        .iter()
+        .any(|&s| format!("{}", numeric) == s)
+    {
+        ereport!(
+        pgrx::PgLogLevel::ERROR,
+        pgrx::PgSqlErrorCode::ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE,
+        "Special numeric values like NaN, Inf, -Inf are not allowed for numeric type during copy to parquet",
+        "Use float types instead.",
+    );
+    }
+}
+
 pub(crate) fn numeric_to_i128(numeric: AnyNumeric, typmod: i32, col_name: &str) -> i128 {
+    error_if_special_numeric(numeric.clone());
+
     let numeric_str = if is_unbounded_numeric_typmod(typmod) {
         let rescaled_unbounded_numeric = rescale_unbounded_numeric_or_error(numeric, col_name);