[SPARK-17258][SQL] Parse scientific decimal literals as decimals

## What changes were proposed in this pull request?
Currently Spark SQL parses regular decimal literals (e.g. `10.00`) as decimals and scientific decimal literals (e.g. `10.0e10`) as doubles. The difference between the two confuses most users. This PR unifies the parsing behavior and also parses scientific decimal literals as decimals.

This implications in tests are limited to a single Hive compatibility test.

## How was this patch tested?
Updated tests in `ExpressionParserSuite` and `SQLQueryTestSuite`.

Author: Herman van Hovell <hvanhovell@databricks.com>

Closes #14828 from hvanhovell/SPARK-17258.

3 files changed, 22 insertions, 12 deletions

diff --git a/sql/core/src/test/resources/sql-tests/inputs/literals.sql b/sql/core/src/test/resources/sql-tests/inputs/literals.sql
index 40dceb19cf..37b4b7606d 100644
--- a/sql/core/src/test/resources/sql-tests/inputs/literals.sql
+++ b/sql/core/src/test/resources/sql-tests/inputs/literals.sql
@@ -50,14 +50,14 @@ select 1D, 1.2D, 1e10, 1.5e5, .10D, 0.10D, .1e5, .9e+2, 0.9e+2, 900e-1, 9.e+1;
 select -1D, -1.2D, -1e10, -1.5e5, -.10D, -0.10D, -.1e5;
 -- negative double
 select .e3;
--- inf and -inf
+-- very large decimals (overflowing double).
 select 1E309, -1E309;
 
 -- decimal parsing
 select 0.3, -0.8, .5, -.18, 0.1111, .1111;
 
--- super large scientific notation numbers should still be valid doubles
-select 123456789012345678901234567890123456789e10, 123456789012345678901234567890123456789.1e10;
+-- super large scientific notation double literals should still be valid doubles
+select 123456789012345678901234567890123456789e10d, 123456789012345678901234567890123456789.1e10d;
 
 -- string
 select "Hello Peter!", 'hello lee!';
@@ -103,3 +103,5 @@ select x'2379ACFe';
 -- invalid hexadecimal binary literal
 select X'XuZ';
 
+-- Hive literal_double test.
+SELECT 3.14, -3.14, 3.14e8, 3.14e-8, -3.14e8, -3.14e-8, 3.14e+8, 3.14E8, 3.14E-8;
diff --git a/sql/core/src/test/resources/sql-tests/results/arithmetic.sql.out b/sql/core/src/test/resources/sql-tests/results/arithmetic.sql.out
index 6abe048af4..ce42c016a7 100644
--- a/sql/core/src/test/resources/sql-tests/results/arithmetic.sql.out
+++ b/sql/core/src/test/resources/sql-tests/results/arithmetic.sql.out
@@ -29,7 +29,7 @@ struct<-5.2:decimal(2,1)>
 -- !query 3
 select +6.8e0
 -- !query 3 schema
-struct<6.8:double>
+struct<6.8:decimal(2,1)>
 -- !query 3 output
 6.8
 
diff --git a/sql/core/src/test/resources/sql-tests/results/literals.sql.out b/sql/core/src/test/resources/sql-tests/results/literals.sql.out
index e2d8daef98..95d4413148 100644
--- a/sql/core/src/test/resources/sql-tests/results/literals.sql.out
+++ b/sql/core/src/test/resources/sql-tests/results/literals.sql.out
@@ -1,5 +1,5 @@
 -- Automatically generated by SQLQueryTestSuite
--- Number of queries: 42
+-- Number of queries: 43
 
 
 -- !query 0
@@ -167,17 +167,17 @@ select 1234567890123456789012345678901234567890.0
 -- !query 17
 select 1D, 1.2D, 1e10, 1.5e5, .10D, 0.10D, .1e5, .9e+2, 0.9e+2, 900e-1, 9.e+1
 -- !query 17 schema
-struct<1.0:double,1.2:double,1.0E10:double,150000.0:double,0.1:double,0.1:double,10000.0:double,90.0:double,90.0:double,90.0:double,90.0:double>
+struct<1.0:double,1.2:double,1E+10:decimal(1,-10),1.5E+5:decimal(2,-4),0.1:double,0.1:double,1E+4:decimal(1,-4),9E+1:decimal(1,-1),9E+1:decimal(1,-1),90.0:decimal(3,1),9E+1:decimal(1,-1)>
 -- !query 17 output
-1.0	1.2	1.0E10	150000.0	0.1	0.1	10000.0	90.0	90.0	90.0	90.0
+1.0	1.2	10000000000	150000	0.1	0.1	10000	90	90	90	90
 
 
 -- !query 18
 select -1D, -1.2D, -1e10, -1.5e5, -.10D, -0.10D, -.1e5
 -- !query 18 schema
-struct<-1.0:double,-1.2:double,-1.0E10:double,-150000.0:double,-0.1:double,-0.1:double,-10000.0:double>
+struct<-1.0:double,-1.2:double,-1E+10:decimal(1,-10),-1.5E+5:decimal(2,-4),-0.1:double,-0.1:double,-1E+4:decimal(1,-4)>
 -- !query 18 output
--1.0	-1.2	-1.0E10	-150000.0	-0.1	-0.1	-10000.0
+-1.0	-1.2	-10000000000	-150000	-0.1	-0.1	-10000
 
 
 -- !query 19
@@ -197,9 +197,9 @@ select .e3
 -- !query 20
 select 1E309, -1E309
 -- !query 20 schema
-struct<Infinity:double,-Infinity:double>
+struct<1E+309:decimal(1,-309),-1E+309:decimal(1,-309)>
 -- !query 20 output
-Infinity	-Infinity
+1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000	-1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
 
 
 -- !query 21
@@ -211,7 +211,7 @@ struct<0.3:decimal(1,1),-0.8:decimal(1,1),0.5:decimal(1,1),-0.18:decimal(2,2),0.
 
 
 -- !query 22
-select 123456789012345678901234567890123456789e10, 123456789012345678901234567890123456789.1e10
+select 123456789012345678901234567890123456789e10d, 123456789012345678901234567890123456789.1e10d
 -- !query 22 schema
 struct<1.2345678901234568E48:double,1.2345678901234568E48:double>
 -- !query 22 output
@@ -408,3 +408,11 @@ contains illegal character for hexBinary: 0XuZ(line 1, pos 7)
 == SQL ==
 select X'XuZ'
 -------^^^
+
+
+-- !query 42
+SELECT 3.14, -3.14, 3.14e8, 3.14e-8, -3.14e8, -3.14e-8, 3.14e+8, 3.14E8, 3.14E-8
+-- !query 42 schema
+struct<3.14:decimal(3,2),-3.14:decimal(3,2),3.14E+8:decimal(3,-6),3.14E-8:decimal(10,10),-3.14E+8:decimal(3,-6),-3.14E-8:decimal(10,10),3.14E+8:decimal(3,-6),3.14E+8:decimal(3,-6),3.14E-8:decimal(10,10)>
+-- !query 42 output
+3.14	-3.14	314000000	0.0000000314	-314000000	-0.0000000314	314000000	314000000	0.0000000314