[SPARK-17246][SQL] Add BigDecimal literal

## What changes were proposed in this pull request?
This PR adds parser support for `BigDecimal` literals. If you append the suffix `BD` to a valid number then this will be interpreted as a `BigDecimal`, for example `12.0E10BD` will interpreted into a BigDecimal with scale -9 and precision 3. This is useful in situations where you need exact values.

## How was this patch tested?
Added tests to `ExpressionParserSuite`, `ExpressionSQLBuilderSuite` and `SQLQueryTestSuite`.

Author: Herman van Hovell <[email protected]>

Closes #14819 from hvanhovell/SPARK-17246.

(cherry picked from commit a11d10f)
Signed-off-by: Reynold Xin <[email protected]>

Author: hvanhovell

sql/catalyst/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBase.g4

@@ -626,6 +626,7 @@ number
     | MINUS? SMALLINT_LITERAL         #smallIntLiteral
     | MINUS? TINYINT_LITERAL          #tinyIntLiteral
     | MINUS? DOUBLE_LITERAL           #doubleLiteral
+    | MINUS? BIGDECIMAL_LITERAL       #bigDecimalLiteral
     ;
 
 nonReserved
@@ -920,6 +921,11 @@ DOUBLE_LITERAL
     (INTEGER_VALUE | DECIMAL_VALUE | SCIENTIFIC_DECIMAL_VALUE) 'D'
     ;
 
+BIGDECIMAL_LITERAL
+    :
+    (INTEGER_VALUE | DECIMAL_VALUE | SCIENTIFIC_DECIMAL_VALUE) 'BD'
+    ;
+
 IDENTIFIER
     : (LETTER | DIGIT | '_')+
     ;

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

@@ -266,7 +266,7 @@ case class Literal (value: Any, dataType: DataType) extends LeafExpression with
         case Double.NegativeInfinity => s"CAST('-Infinity' AS ${DoubleType.sql})"
         case _ => v + "D"
       }
-    case (v: Decimal, t: DecimalType) => s"CAST($v AS ${t.sql})"
+    case (v: Decimal, t: DecimalType) => v + "BD"
     case (v: Int, DateType) => s"DATE '${DateTimeUtils.toJavaDate(v)}'"
     case (v: Long, TimestampType) => s"TIMESTAMP('${DateTimeUtils.toJavaTimestamp(v)}')"
     case _ => value.toString

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala

@@ -26,7 +26,8 @@ import org.antlr.v4.runtime.{ParserRuleContext, Token}
 import org.antlr.v4.runtime.tree.{ParseTree, RuleNode, TerminalNode}
 
 import org.apache.spark.internal.Logging
-import org.apache.spark.sql.catalyst.{FunctionIdentifier, InternalRow, TableIdentifier}
+import org.apache.spark.sql.AnalysisException
+import org.apache.spark.sql.catalyst.{FunctionIdentifier, TableIdentifier}
 import org.apache.spark.sql.catalyst.analysis._
 import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.catalyst.parser.SqlBaseParser._
@@ -1318,6 +1319,19 @@ class AstBuilder extends SqlBaseBaseVisitor[AnyRef] with Logging {
     numericLiteral(ctx, Double.MinValue, Double.MaxValue, DoubleType.simpleString)(_.toDouble)
   }
 
+  /**
+   * Create a BigDecimal Literal expression.
+   */
+  override def visitBigDecimalLiteral(ctx: BigDecimalLiteralContext): Literal = {
+    val raw = ctx.getText.substring(0, ctx.getText.length - 2)
+    try {
+      Literal(BigDecimal(raw).underlying())
+    } catch {
+      case e: AnalysisException =>
+        throw new ParseException(e.message, ctx)
+    }
+  }
+
   /**
    * Create a String literal expression.
    */

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/ExpressionParserSuite.scala

@@ -392,6 +392,13 @@ class ExpressionParserSuite extends PlanTest {
     intercept("1.8E308D", s"does not fit in range")
     // TODO we need to figure out if we should throw an exception here!
     assertEqual("1E309", Literal(Double.PositiveInfinity))
+
+    // BigDecimal Literal
+    assertEqual("90912830918230182310293801923652346786BD",
+      Literal(BigDecimal("90912830918230182310293801923652346786").underlying()))
+    assertEqual("123.0E-28BD", Literal(BigDecimal("123.0E-28").underlying()))
+    assertEqual("123.08BD", Literal(BigDecimal("123.08").underlying()))
+    intercept("1.20E-38BD", "DecimalType can only support precision up to 38")
   }
 
   test("strings") {

sql/core/src/test/resources/sql-tests/inputs/literals.sql

@@ -90,3 +90,9 @@ select interval 10 nanoseconds;
 
 -- unsupported data type
 select GEO '(10,-6)';
+
+-- big decimal parsing
+select 90912830918230182310293801923652346786BD, 123.0E-28BD, 123.08BD;
+
+-- out of range big decimal
+select 1.20E-38BD;

sql/core/src/test/resources/sql-tests/results/literals.sql.out

@@ -1,5 +1,5 @@
 -- Automatically generated by SQLQueryTestSuite
--- Number of queries: 38
+-- Number of queries: 40
 
 
 -- !query 0
@@ -354,3 +354,25 @@ Literals of type 'GEO' are currently not supported.(line 1, pos 7)
 == SQL ==
 select GEO '(10,-6)'
 -------^^^
+
+
+-- !query 38
+select 90912830918230182310293801923652346786BD, 123.0E-28BD, 123.08BD
+-- !query 38 schema
+struct<90912830918230182310293801923652346786:decimal(38,0),1.230E-26:decimal(29,29),123.08:decimal(5,2)>
+-- !query 38 output
+90912830918230182310293801923652346786	0.0000000000000000000000000123	123.08
+
+
+-- !query 39
+select 1.20E-38BD
+-- !query 39 schema
+struct<>
+-- !query 39 output
+org.apache.spark.sql.catalyst.parser.ParseException
+
+DecimalType can only support precision up to 38(line 1, pos 7)
+
+== SQL ==
+select 1.20E-38BD
+-------^^^

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

@@ -39,6 +39,7 @@ class ExpressionSQLBuilderSuite extends SQLBuilderTest {
     checkSQL(Literal(Double.PositiveInfinity), "CAST('Infinity' AS DOUBLE)")
     checkSQL(Literal(Double.NegativeInfinity), "CAST('-Infinity' AS DOUBLE)")
     checkSQL(Literal(Double.NaN), "CAST('NaN' AS DOUBLE)")
+    checkSQL(Literal(BigDecimal("10.0000000").underlying), "10.0000000BD")
     checkSQL(
       Literal(Timestamp.valueOf("2016-01-01 00:00:00")), "TIMESTAMP('2016-01-01 00:00:00.0')")
     // TODO tests for decimals