[SPARK-29761][SQL] do not output leading 'interval' in CalendarInterval.toString

common/unsafe/src/main/java/org/apache/spark/unsafe/types/CalendarInterval.java

@@ -84,35 +84,38 @@ public int hashCode() {
 
   @Override
   public String toString() {
-    StringBuilder sb = new StringBuilder("interval");
+    if (months == 0 && days == 0 && microseconds == 0) {
+      return "0 seconds";
+    }
+
+    StringBuilder sb = new StringBuilder();
 
     if (months != 0) {
-      appendUnit(sb, months / 12, "year");
-      appendUnit(sb, months % 12, "month");
+      appendUnit(sb, months / 12, "years");
+      appendUnit(sb, months % 12, "months");
     }
 
-    appendUnit(sb, days, "day");
+    appendUnit(sb, days, "days");
 
     if (microseconds != 0) {
       long rest = microseconds;
-      appendUnit(sb, rest / MICROS_PER_HOUR, "hour");
+      appendUnit(sb, rest / MICROS_PER_HOUR, "hours");
       rest %= MICROS_PER_HOUR;
-      appendUnit(sb, rest / MICROS_PER_MINUTE, "minute");
+      appendUnit(sb, rest / MICROS_PER_MINUTE, "minutes");
       rest %= MICROS_PER_MINUTE;
       if (rest != 0) {
         String s = BigDecimal.valueOf(rest, 6).stripTrailingZeros().toPlainString();
-        sb.append(' ').append(s).append(" seconds");
+        sb.append(s).append(" seconds ");
       }
-    } else if (months == 0 && days == 0) {
-      sb.append(" 0 microseconds");
     }
 
+    sb.setLength(sb.length() - 1);
     return sb.toString();
   }
 
   private void appendUnit(StringBuilder sb, long value, String unit) {
     if (value != 0) {
-      sb.append(' ').append(value).append(' ').append(unit).append('s');
+      sb.append(value).append(' ').append(unit).append(' ');
     }
   }
 

common/unsafe/src/test/java/org/apache/spark/unsafe/types/CalendarIntervalSuite.java

@@ -51,28 +51,28 @@ public void toStringTest() {
     CalendarInterval i;
 
     i = new CalendarInterval(0, 0, 0);
-    assertEquals("interval 0 microseconds", i.toString());
+    assertEquals("0 seconds", i.toString());
 
     i = new CalendarInterval(34, 0, 0);
-    assertEquals("interval 2 years 10 months", i.toString());
+    assertEquals("2 years 10 months", i.toString());
 
     i = new CalendarInterval(-34, 0, 0);
-    assertEquals("interval -2 years -10 months", i.toString());
+    assertEquals("-2 years -10 months", i.toString());
 
     i = new CalendarInterval(0, 31, 0);
-    assertEquals("interval 31 days", i.toString());
+    assertEquals("31 days", i.toString());
 
     i = new CalendarInterval(0, -31, 0);
-    assertEquals("interval -31 days", i.toString());
+    assertEquals("-31 days", i.toString());
 
     i = new CalendarInterval(0, 0, 3 * MICROS_PER_HOUR + 13 * MICROS_PER_MINUTE + 123);
-    assertEquals("interval 3 hours 13 minutes 0.000123 seconds", i.toString());
+    assertEquals("3 hours 13 minutes 0.000123 seconds", i.toString());
 
     i = new CalendarInterval(0, 0, -3 * MICROS_PER_HOUR - 13 * MICROS_PER_MINUTE - 123);
-    assertEquals("interval -3 hours -13 minutes -0.000123 seconds", i.toString());
+    assertEquals("-3 hours -13 minutes -0.000123 seconds", i.toString());
 
     i = new CalendarInterval(34, 31, 3 * MICROS_PER_HOUR + 13 * MICROS_PER_MINUTE + 123);
-    assertEquals("interval 2 years 10 months 31 days 3 hours 13 minutes 0.000123 seconds",
+    assertEquals("2 years 10 months 31 days 3 hours 13 minutes 0.000123 seconds",
       i.toString());
   }
 

docs/sql-migration-guide.md

@@ -222,6 +222,8 @@ license: |
 
   - Since Spark 3.0, the interval literal syntax does not allow multiple from-to units anymore. For example, `SELECT INTERVAL '1-1' YEAR TO MONTH '2-2' YEAR TO MONTH'` throws parser exception.
 
+  - Since Spark 3.0, when casting interval values to string type, there is no "interval" prefix, e.g. `1 days 2 hours`. In Spark version 2.4 and earlier, the string contains the "interval" prefix like `interval 1 days 2 hours`.
+
 ## Upgrading from Spark SQL 2.4 to 2.4.1
 
   - The value of `spark.executor.heartbeatInterval`, when specified without units like "30" rather than "30s", was

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Sum.scala

@@ -34,7 +34,7 @@ import org.apache.spark.sql.types._
       > SELECT _FUNC_(col) FROM VALUES (NULL), (NULL) AS tab(col);
        NULL
       > SELECT _FUNC_(cast(col as interval)) FROM VALUES ('1 seconds'), ('2 seconds'), (null) tab(col);
-       interval 3 seconds
+       3 seconds
   """,
   since = "1.0.0")
 // scalastyle:on line.size.limit

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala

@@ -669,7 +669,7 @@ abstract class CastSuiteBase extends SparkFunSuite with ExpressionEvalHelper {
     checkEvaluation(Cast(Literal.create(
       new CalendarInterval(15, 9, -3 * CalendarInterval.MICROS_PER_HOUR), CalendarIntervalType),
       StringType),
-      "interval 1 years 3 months 9 days -3 hours")
+      "1 years 3 months 9 days -3 hours")
     checkEvaluation(Cast(Literal("INTERVAL 1 Second 1 microsecond"), CalendarIntervalType),
       new CalendarInterval(0, 0, 1000001))
     checkEvaluation(Cast(Literal("1 MONTH 1 Microsecond"), CalendarIntervalType),

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ExpressionSQLBuilderSuite.scala

@@ -169,12 +169,12 @@ class ExpressionSQLBuilderSuite extends SparkFunSuite {
 
     checkSQL(
       TimeAdd('a, interval),
-      "`a` + interval 1 hours"
+      "`a` + 1 hours"
     )
 
     checkSQL(
       TimeSub('a, interval),
-      "`a` - interval 1 hours"
+      "`a` - 1 hours"
     )
   }
 }