[SPARK-29012][SQL] Support special timestamp values

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/datetimeExpressions.scala

@@ -98,9 +98,7 @@ case class CurrentTimestamp() extends LeafExpression with CodegenFallback {
 
   override def dataType: DataType = TimestampType
 
-  override def eval(input: InternalRow): Any = {
-    instantToMicros(Instant.now())
-  }
+  override def eval(input: InternalRow): Any = currentTimestamp()
 
   override def prettyName: String = "current_timestamp"
 }

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/DateTimeUtils.scala

@@ -17,12 +17,14 @@
 
 package org.apache.spark.sql.catalyst.util
 
+import java.nio.charset.StandardCharsets
 import java.sql.{Date, Timestamp}
 import java.time._
 import java.time.temporal.{ChronoField, ChronoUnit, IsoFields}
 import java.util.{Locale, TimeZone}
 import java.util.concurrent.TimeUnit._
 
+import scala.util.Try
 import scala.util.control.NonFatal
 
 import org.apache.spark.sql.types.Decimal
@@ -218,6 +220,8 @@ object DateTimeUtils {
     var i = 0
     var currentSegmentValue = 0
     val bytes = s.trim.getBytes
+    val specialTimestamp = convertSpecialTimestamp(bytes, timeZoneId)
+    if (specialTimestamp.isDefined) return specialTimestamp
     var j = 0
     var digitsMilli = 0
     var justTime = false
@@ -848,4 +852,67 @@ object DateTimeUtils {
     val sinceEpoch = BigDecimal(timestamp) / MICROS_PER_SECOND + offset
     new Decimal().set(sinceEpoch, 20, 6)
   }
+
+  def currentTimestamp(): SQLTimestamp = instantToMicros(Instant.now())
+
+  private def today(zoneId: ZoneId): ZonedDateTime = {
+    Instant.now().atZone(zoneId).`with`(LocalTime.MIDNIGHT)
+  }
+
+  private val specialValueRe = """(\p{Alpha}+)\p{Blank}*(.*)""".r
+
+  /**
+   * Extracts special values from an input string ignoring case.
+   * @param input - a trimmed string
+   * @param zoneId - zone identifier used to get the current date.
+   * @return some special value in lower case or None.
+   */
+  private def extractSpecialValue(input: String, zoneId: ZoneId): Option[String] = {
+    def isValid(value: String, timeZoneId: String): Boolean = {
+      // Special value can be without any time zone
+      if (timeZoneId.isEmpty) return true
+      // "now" must not have the time zone field
+      if (value.compareToIgnoreCase("now") == 0) return false
+      // If the time zone field presents in the input, it must be resolvable
+      try {
+        getZoneId(timeZoneId)
+        true
+      } catch {
+        case NonFatal(_) => false
+      }
+    }
+
+    assert(input.trim.length == input.length)
+    if (input.length < 3 || !input(0).isLetter) return None
+    input match {
+      case specialValueRe(v, z) if isValid(v, z) => Some(v.toLowerCase(Locale.US))
+      case _ => None
+    }
+  }
+
+  /**
+   * Converts notational shorthands that are converted to ordinary timestamps.
+   * @param input - a trimmed string
+   * @param zoneId - zone identifier used to get the current date.
+   * @return some of microseconds since the epoch if the conversion completed
+   *         successfully otherwise None.
+   */
+  def convertSpecialTimestamp(input: String, zoneId: ZoneId): Option[SQLTimestamp] = {
+    extractSpecialValue(input, zoneId).flatMap {
+      case "epoch" => Some(0)
+      case "now" => Some(currentTimestamp())
+      case "today" => Some(instantToMicros(today(zoneId).toInstant))
+      case "tomorrow" => Some(instantToMicros(today(zoneId).plusDays(1).toInstant))
+      case "yesterday" => Some(instantToMicros(today(zoneId).minusDays(1).toInstant))
+      case _ => None
+    }
+  }
+
+  private def convertSpecialTimestamp(bytes: Array[Byte], zoneId: ZoneId): Option[SQLTimestamp] = {
+    if (bytes.length > 0 && Character.isAlphabetic(bytes(0))) {
+      convertSpecialTimestamp(new String(bytes, StandardCharsets.UTF_8), zoneId)
+    } else {
+      None
+    }
+  }
 }

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/TimestampFormatter.scala

@@ -22,9 +22,11 @@ import java.time._
 import java.time.format.DateTimeParseException
 import java.time.temporal.ChronoField.MICRO_OF_SECOND
 import java.time.temporal.TemporalQueries
-import java.util.{Locale, TimeZone}
+import java.util.Locale
 import java.util.concurrent.TimeUnit.SECONDS
 
+import DateTimeUtils.convertSpecialTimestamp
+
 sealed trait TimestampFormatter extends Serializable {
   /**
    * Parses a timestamp in a string and converts it to microseconds.
@@ -50,14 +52,17 @@ class Iso8601TimestampFormatter(
   protected lazy val formatter = getOrCreateFormatter(pattern, locale)
 
   override def parse(s: String): Long = {
-    val parsed = formatter.parse(s)
-    val parsedZoneId = parsed.query(TemporalQueries.zone())
-    val timeZoneId = if (parsedZoneId == null) zoneId else parsedZoneId
-    val zonedDateTime = toZonedDateTime(parsed, timeZoneId)
-    val epochSeconds = zonedDateTime.toEpochSecond
-    val microsOfSecond = zonedDateTime.get(MICRO_OF_SECOND)
+    val specialDate = convertSpecialTimestamp(s.trim, zoneId)
+    specialDate.getOrElse {
+      val parsed = formatter.parse(s)
+      val parsedZoneId = parsed.query(TemporalQueries.zone())
+      val timeZoneId = if (parsedZoneId == null) zoneId else parsedZoneId
+      val zonedDateTime = toZonedDateTime(parsed, timeZoneId)
+      val epochSeconds = zonedDateTime.toEpochSecond
+      val microsOfSecond = zonedDateTime.get(MICRO_OF_SECOND)
 
-    Math.addExact(SECONDS.toMicros(epochSeconds), microsOfSecond)
+      Math.addExact(SECONDS.toMicros(epochSeconds), microsOfSecond)
+    }
   }
 
   override def format(us: Long): String = {

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/util/DateTimeUtilsSuite.scala

@@ -19,16 +19,18 @@ package org.apache.spark.sql.catalyst.util
 
 import java.sql.{Date, Timestamp}
 import java.text.SimpleDateFormat
-import java.time.ZoneId
+import java.time.{LocalDateTime, LocalTime, ZoneId}
 import java.util.{Locale, TimeZone}
 import java.util.concurrent.TimeUnit
 
+import org.scalatest.Matchers
+
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.sql.catalyst.util.DateTimeTestUtils._
 import org.apache.spark.sql.catalyst.util.DateTimeUtils._
 import org.apache.spark.unsafe.types.UTF8String
 
-class DateTimeUtilsSuite extends SparkFunSuite {
+class DateTimeUtilsSuite extends SparkFunSuite with Matchers {
 
   val TimeZonePST = TimeZone.getTimeZone("PST")
   private def defaultZoneId = ZoneId.systemDefault()
@@ -142,10 +144,14 @@ class DateTimeUtilsSuite extends SparkFunSuite {
     assert(stringToDate(UTF8String.fromString("1999 08")).isEmpty)
   }
 
+  private def toTimestamp(str: String, zoneId: ZoneId): Option[SQLTimestamp] = {
+    stringToTimestamp(UTF8String.fromString(str), zoneId)
+  }
+
   test("string to timestamp") {
     for (tz <- ALL_TIMEZONES) {
       def checkStringToTimestamp(str: String, expected: Option[Long]): Unit = {
-        assert(stringToTimestamp(UTF8String.fromString(str), tz.toZoneId) === expected)
+        assert(toTimestamp(str, tz.toZoneId) === expected)
       }
 
       checkStringToTimestamp("1969-12-31 16:00:00", Option(date(1969, 12, 31, 16, tz = tz)))
@@ -271,8 +277,8 @@ class DateTimeUtilsSuite extends SparkFunSuite {
       UTF8String.fromString("2015-02-29 00:00:00"), defaultZoneId).isEmpty)
     assert(stringToTimestamp(
       UTF8String.fromString("2015-04-31 00:00:00"), defaultZoneId).isEmpty)
-    assert(stringToTimestamp(UTF8String.fromString("2015-02-29"), defaultZoneId).isEmpty)
-    assert(stringToTimestamp(UTF8String.fromString("2015-04-31"), defaultZoneId).isEmpty)
+    assert(toTimestamp("2015-02-29", defaultZoneId).isEmpty)
+    assert(toTimestamp("2015-04-31", defaultZoneId).isEmpty)
   }
 
   test("hours") {
@@ -456,8 +462,7 @@ class DateTimeUtilsSuite extends SparkFunSuite {
         timezone: TimeZone = DateTimeUtils.defaultTimeZone()): Unit = {
       val truncated =
         DateTimeUtils.truncTimestamp(inputTS, level, timezone)
-      val expectedTS =
-        DateTimeUtils.stringToTimestamp(UTF8String.fromString(expected), defaultZoneId)
+      val expectedTS = toTimestamp(expected, defaultZoneId)
       assert(truncated === expectedTS.get)
     }
 
@@ -564,4 +569,21 @@ class DateTimeUtilsSuite extends SparkFunSuite {
     assert(DateTimeUtils.toMillis(-9223372036844776001L) === -9223372036844777L)
     assert(DateTimeUtils.toMillis(-157700927876544L) === -157700927877L)
   }
+
+  test("special timestamp values") {
+    DateTimeTestUtils.outstandingZoneIds.foreach { zoneId =>
+      val tolerance = TimeUnit.SECONDS.toMicros(30)
+
+      assert(toTimestamp("Epoch", zoneId).get === 0)
+      val now = instantToMicros(LocalDateTime.now(zoneId).atZone(zoneId).toInstant)
+      toTimestamp("NOW", zoneId).get should be (now +- tolerance)
+      assert(toTimestamp("now UTC", zoneId) === None)
+      val today = instantToMicros(LocalDateTime.now(zoneId)
+        .`with`(LocalTime.MIDNIGHT)
+        .atZone(zoneId).toInstant)
+      toTimestamp(" Yesterday", zoneId).get should be (today - MICROS_PER_DAY +- tolerance)
+      toTimestamp("Today ", zoneId).get should be (today +- tolerance)
+      toTimestamp(" tomorrow CET ", zoneId).get should be (today + MICROS_PER_DAY +- tolerance)
+    }
+  }
 }

sql/catalyst/src/test/scala/org/apache/spark/sql/util/TimestampFormatterSuite.scala

@@ -17,14 +17,18 @@
 
 package org.apache.spark.sql.util
 
-import java.time.{LocalDateTime, ZoneId, ZoneOffset}
+import java.time.{LocalDateTime, LocalTime, ZoneOffset}
 import java.util.concurrent.TimeUnit
 
+import org.scalatest.Matchers
+
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.sql.catalyst.plans.SQLHelper
 import org.apache.spark.sql.catalyst.util.{DateTimeTestUtils, DateTimeUtils, TimestampFormatter}
+import org.apache.spark.sql.catalyst.util.DateTimeUtils.{getZoneId, instantToMicros, MICROS_PER_DAY}
+import org.apache.spark.sql.internal.SQLConf
 
-class TimestampFormatterSuite extends SparkFunSuite with SQLHelper {
+class TimestampFormatterSuite extends SparkFunSuite with SQLHelper with Matchers {
 
   test("parsing timestamps using time zones") {
     val localDate = "2018-12-02T10:11:12.001234"
@@ -131,4 +135,24 @@ class TimestampFormatterSuite extends SparkFunSuite with SQLHelper {
     val micros = DateTimeUtils.instantToMicros(instant)
     assert(TimestampFormatter(ZoneOffset.UTC).format(micros) === "-0099-01-01 00:00:00")
   }
+
+  test("special timestamp values") {
+    DateTimeTestUtils.outstandingTimezonesIds.foreach { timeZone =>
+      withSQLConf(SQLConf.SESSION_LOCAL_TIMEZONE.key -> timeZone) {
+        val zoneId = getZoneId(timeZone)
+        val formatter = TimestampFormatter(zoneId)
+        val tolerance = TimeUnit.SECONDS.toMicros(30)
+
+        assert(formatter.parse("EPOCH") === 0)
+        val now = instantToMicros(LocalDateTime.now(zoneId).atZone(zoneId).toInstant)
+        formatter.parse("now") should be (now +- tolerance)
+        val today = instantToMicros(LocalDateTime.now(zoneId)
+          .`with`(LocalTime.MIDNIGHT)
+          .atZone(zoneId).toInstant)
+        formatter.parse("yesterday CET") should be (today - MICROS_PER_DAY +- tolerance)
+        formatter.parse(" TODAY ") should be (today +- tolerance)
+        formatter.parse("Tomorrow ") should be (today + MICROS_PER_DAY +- tolerance)
+      }
+    }
+  }
 }

sql/core/src/test/resources/sql-tests/inputs/pgSQL/timestamp.sql

@@ -7,7 +7,6 @@
 
 CREATE TABLE TIMESTAMP_TBL (d1 timestamp) USING parquet;
 
--- [SPARK-28141] Timestamp type can not accept special values
 -- Test shorthand input values
 -- We can't just "select" the results since they aren't constants; test for
 -- equality instead.  We can do that by running the test inside a transaction
@@ -17,22 +16,24 @@ CREATE TABLE TIMESTAMP_TBL (d1 timestamp) USING parquet;
 -- block is entered exactly at local midnight; then 'now' and 'today' have
 -- the same values and the counts will come out different.
 
--- INSERT INTO TIMESTAMP_TBL VALUES ('now');
+INSERT INTO TIMESTAMP_TBL VALUES ('now');
 -- SELECT pg_sleep(0.1);
 
 -- BEGIN;
 
--- INSERT INTO TIMESTAMP_TBL VALUES ('now');
--- INSERT INTO TIMESTAMP_TBL VALUES ('today');
--- INSERT INTO TIMESTAMP_TBL VALUES ('yesterday');
--- INSERT INTO TIMESTAMP_TBL VALUES ('tomorrow');
+INSERT INTO TIMESTAMP_TBL VALUES ('now');
+INSERT INTO TIMESTAMP_TBL VALUES ('today');
+INSERT INTO TIMESTAMP_TBL VALUES ('yesterday');
+INSERT INTO TIMESTAMP_TBL VALUES ('tomorrow');
 -- time zone should be ignored by this data type
--- INSERT INTO TIMESTAMP_TBL VALUES ('tomorrow EST');
--- INSERT INTO TIMESTAMP_TBL VALUES ('tomorrow zulu');
-
--- SELECT count(*) AS One FROM TIMESTAMP_TBL WHERE d1 = timestamp 'today';
--- SELECT count(*) AS Three FROM TIMESTAMP_TBL WHERE d1 = timestamp 'tomorrow';
--- SELECT count(*) AS One FROM TIMESTAMP_TBL WHERE d1 = timestamp 'yesterday';
+INSERT INTO TIMESTAMP_TBL VALUES ('tomorrow EST');
+-- [SPARK-29024] Ignore case while resolving time zones
+INSERT INTO TIMESTAMP_TBL VALUES ('tomorrow Zulu');
+
+SELECT count(*) AS One FROM TIMESTAMP_TBL WHERE d1 = timestamp 'today';
+SELECT count(*) AS Three FROM TIMESTAMP_TBL WHERE d1 = timestamp 'tomorrow';
+SELECT count(*) AS One FROM TIMESTAMP_TBL WHERE d1 = timestamp 'yesterday';
+-- [SPARK-29025] Support seconds precision by the timestamp type
 -- SELECT count(*) AS One FROM TIMESTAMP_TBL WHERE d1 = timestamp(2) 'now';
 
 -- COMMIT;
@@ -48,12 +49,12 @@ CREATE TABLE TIMESTAMP_TBL (d1 timestamp) USING parquet;
 -- SELECT count(*) AS two FROM TIMESTAMP_TBL WHERE d1 = timestamp(2) 'now';
 -- COMMIT;
 
--- TRUNCATE TIMESTAMP_TBL;
+TRUNCATE TABLE TIMESTAMP_TBL;
 
 -- Special values
 -- INSERT INTO TIMESTAMP_TBL VALUES ('-infinity');
 -- INSERT INTO TIMESTAMP_TBL VALUES ('infinity');
--- INSERT INTO TIMESTAMP_TBL VALUES ('epoch');
+INSERT INTO TIMESTAMP_TBL VALUES ('epoch');
 -- [SPARK-27923] Spark SQL insert there obsolete special values to NULL
 -- Obsolete special values
 -- INSERT INTO TIMESTAMP_TBL VALUES ('invalid');