[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 <hvanhovell@databricks.com>

Closes #14819 from hvanhovell/SPARK-17246.

1 files changed, 7 insertions, 0 deletions

diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/ExpressionParserSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/ExpressionParserSuite.scala
index 401d9cd9d2..dbc5db39ae 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/ExpressionParserSuite.scala
+++ b/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") {