Implement extraction of the corresponding date part from a date or timestamp (#302)

* Implement extracts the corresponding date part from a date or timestamp

* Add units for visit expressions

Author: osipovartem

crates/runtime/src/execution/query.rs

@@ -1404,3 +1404,39 @@ mod tests {
         }
     }
 }
+
+#[cfg(test)]
+mod test {
+    use crate::datafusion::execution::SqlExecutor;
+    use datafusion::sql::parser::DFParser;
+
+    #[allow(clippy::unwrap_used)]
+    #[test]
+    fn test_postprocess_query_statement_functions_expressions() {
+        let args: [(&str, &str); 14] = [
+            ("select year(ts)", "SELECT date_part('year', ts)"),
+            ("select dayofyear(ts)", "SELECT date_part('doy', ts)"),
+            ("select day(ts)", "SELECT date_part('day', ts)"),
+            ("select dayofmonth(ts)", "SELECT date_part('day', ts)"),
+            ("select dayofweek(ts)", "SELECT date_part('dow', ts)"),
+            ("select month(ts)", "SELECT date_part('month', ts)"),
+            ("select weekofyear(ts)", "SELECT date_part('week', ts)"),
+            ("select week(ts)", "SELECT date_part('week', ts)"),
+            ("select hour(ts)", "SELECT date_part('hour', ts)"),
+            ("select minute(ts)", "SELECT date_part('minute', ts)"),
+            ("select second(ts)", "SELECT date_part('second', ts)"),
+            ("select minute(ts)", "SELECT date_part('minute', ts)"),
+            // Do nothing
+            ("select yearofweek(ts)", "SELECT yearofweek(ts)"),
+            ("select yearofweekiso(ts)", "SELECT yearofweekiso(ts)"),
+        ];
+
+        for (init, exp) in args {
+            let statement = DFParser::parse_sql(init).unwrap().pop_front();
+            if let Some(mut s) = statement {
+                SqlExecutor::postprocess_query_statement(&mut s);
+                assert_eq!(s.to_string(), exp);
+            }
+        }
+    }
+}