From 11d427c924d303e20af90c0179a105f6ff4d89e2 Mon Sep 17 00:00:00 2001
From: petermaxlee <petermaxlee@gmail.com>
Date: Thu, 28 Jul 2016 13:13:17 +0800
Subject: [SPARK-16730][SQL] Implement function aliases for type casts

## What changes were proposed in this pull request?
Spark 1.x supports using the Hive type name as function names for doing casts, e.g.
```sql
SELECT int(1.0);
SELECT string(2.0);
```

The above query would work in Spark 1.x because Spark 1.x fail back to Hive for unimplemented functions, and break in Spark 2.0 because the fall back was removed.

This patch implements function aliases using an analyzer rule for the following cast functions:
- boolean
- tinyint
- smallint
- int
- bigint
- float
- double
- decimal
- date
- timestamp
- binary
- string

## How was this patch tested?
Added end-to-end tests in SQLCompatibilityFunctionSuite.

Author: petermaxlee <petermaxlee@gmail.com>

Closes #14364 from petermaxlee/SPARK-16730-2.
---
 .../spark/sql/SQLCompatibilityFunctionSuite.scala  | 26 ++++++++++++++++++++++
 1 file changed, 26 insertions(+)

(limited to 'sql/core/src')

diff --git a/sql/core/src/test/scala/org/apache/spark/sql/SQLCompatibilityFunctionSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/SQLCompatibilityFunctionSuite.scala
index 1e3239550f..27b60e0d9d 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/SQLCompatibilityFunctionSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/SQLCompatibilityFunctionSuite.scala
@@ -17,10 +17,14 @@
 
 package org.apache.spark.sql
 
+import java.math.BigDecimal
+import java.sql.Timestamp
+
 import org.apache.spark.sql.test.SharedSQLContext
 
 /**
  * A test suite for functions added for compatibility with other databases such as Oracle, MSSQL.
+ *
  * These functions are typically implemented using the trait
  * [[org.apache.spark.sql.catalyst.expressions.RuntimeReplaceable]].
  */
@@ -69,4 +73,26 @@ class SQLCompatibilityFunctionSuite extends QueryTest with SharedSQLContext {
       sql("SELECT nvl2(null, 1, 2.1d), nvl2('n', 1, 2.1d)"),
       Row(2.1, 1.0))
   }
+
+  test("SPARK-16730 cast alias functions for Hive compatibility") {
+    checkAnswer(
+      sql("SELECT boolean(1), tinyint(1), smallint(1), int(1), bigint(1)"),
+      Row(true, 1.toByte, 1.toShort, 1, 1L))
+
+    checkAnswer(
+      sql("SELECT float(1), double(1), decimal(1)"),
+      Row(1.toFloat, 1.0, new BigDecimal(1)))
+
+    checkAnswer(
+      sql("SELECT date(\"2014-04-04\"), timestamp(date(\"2014-04-04\"))"),
+      Row(new java.util.Date(114, 3, 4), new Timestamp(114, 3, 4, 0, 0, 0, 0)))
+
+    checkAnswer(
+      sql("SELECT string(1)"),
+      Row("1"))
+
+    // Error handling: only one argument
+    val errorMsg = intercept[AnalysisException](sql("SELECT string(1, 2)")).getMessage
+    assert(errorMsg.contains("Function string accepts only one argument"))
+  }
 }
-- 
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