[CALCITE-3282] In JDBC adadpter, when generating SQL for Hive, genera…

…te INTEGER type as INT (huangfeng)

This is necessary because Hive 1.x only supports INT, not INTEGER.

Fix-up (by Danny):
* Add issue link to the test case;
* Fix some doc typos.

close #1443

core/src/main/java/org/apache/calcite/sql/SqlDialect.java

@@ -749,6 +749,8 @@ public boolean supportsDataType(RelDataType type) {
     return true;
   }
 
+ /** Returns SqlNode for type in "cast(column as type)", which might be
+  * different between databases by type name, precision etc. */
   public SqlNode getCastSpec(RelDataType type) {
     if (type instanceof BasicSqlType) {
       int maxPrecision = -1;

core/src/main/java/org/apache/calcite/sql/dialect/HiveSqlDialect.java

@@ -17,15 +17,21 @@
 package org.apache.calcite.sql.dialect;
 
 import org.apache.calcite.config.NullCollation;
+import org.apache.calcite.rel.type.RelDataType;
 import org.apache.calcite.sql.SqlCall;
+import org.apache.calcite.sql.SqlDataTypeSpec;
 import org.apache.calcite.sql.SqlDialect;
+import org.apache.calcite.sql.SqlIdentifier;
 import org.apache.calcite.sql.SqlLiteral;
 import org.apache.calcite.sql.SqlNode;
 import org.apache.calcite.sql.SqlOperator;
 import org.apache.calcite.sql.SqlSyntax;
+import org.apache.calcite.sql.SqlUserDefinedTypeNameSpec;
 import org.apache.calcite.sql.SqlWriter;
 import org.apache.calcite.sql.fun.SqlStdOperatorTable;
 import org.apache.calcite.sql.fun.SqlTrimFunction;
+import org.apache.calcite.sql.parser.SqlParserPos;
+import org.apache.calcite.sql.type.BasicSqlType;
 
 /**
  * A <code>SqlDialect</code> implementation for the Apache Hive database.
@@ -120,6 +126,18 @@ private void unparseTrim(SqlWriter writer, SqlCall call, int leftPrec,
   @Override public boolean supportsCharSet() {
     return false;
   }
+
+  @Override public SqlNode getCastSpec(final RelDataType type) {
+    if (type instanceof BasicSqlType) {
+      switch (type.getSqlTypeName()) {
+      case INTEGER:
+        SqlUserDefinedTypeNameSpec typeNameSpec = new SqlUserDefinedTypeNameSpec(
+            new SqlIdentifier("INT", SqlParserPos.ZERO), SqlParserPos.ZERO);
+        return new SqlDataTypeSpec(typeNameSpec, SqlParserPos.ZERO);
+      }
+    }
+    return super.getCastSpec(type);
+  }
 }
 
 // End HiveSqlDialect.java

core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java

@@ -803,6 +803,18 @@ private static String toSql(RelNode root, SqlDialect dialect) {
     sql(query).withHive().ok(expected);
   }
 
+  /** Test case for
+   * <a href="https://issues.apache.org/jira/browse/CALCITE-3282">[CALCITE-3282]
+   * HiveSqlDialect unparse Interger type as Int in order
+   * to be compatible with Hive1.x</a>. */
+  @Test public void testHiveCastAsInt() {
+    String query = "select cast( cast(\"employee_id\" as varchar) as int) "
+        + "from \"foodmart\".\"reserve_employee\" ";
+    final String expected = "SELECT CAST(CAST(employee_id AS VARCHAR) AS INT)\n"
+        + "FROM foodmart.reserve_employee";
+    sql(query).withHive().ok(expected);
+  }
+
   /** Test case for
    * <a href="https://issues.apache.org/jira/browse/CALCITE-3220">[CALCITE-3220]
    * HiveSqlDialect should transform the SQL-standard TRIM function to TRIM,