commit 655bd35f8ebb66eefc8e39599a313313a474af51
Author: Tim Armstrong <tarmstrong@cloudera.com>
Date:   Wed Nov 23 10:06:58 2016 -0800

    WIP

diff --git a/fe/src/main/java/org/apache/impala/analysis/ToSqlUtils.java b/fe/src/main/java/org/apache/impala/analysis/ToSqlUtils.java
index f01a78c..3c0b850 100644
--- a/fe/src/main/java/org/apache/impala/analysis/ToSqlUtils.java
+++ b/fe/src/main/java/org/apache/impala/analysis/ToSqlUtils.java
@@ -91,12 +91,7 @@ public class ToSqlUtils {
     // are needed if this identifier will be preceded by a ".".
     boolean startsWithNumber = false;
     if (!hiveNeedsQuotes && !isImpalaKeyword) {
-      try {
-        Integer.parseInt(ident.substring(0, 1));
-        startsWithNumber = true;
-      } catch (NumberFormatException e) {
-        // Ignore exception, identifier does not start with number.
-      }
+      startsWithNumber = Character.isDigit(ident.charAt(0));
     }
     if (hiveNeedsQuotes || isImpalaKeyword || startsWithNumber) return "`" + ident + "`";
     return ident;
diff --git a/tests/query_test/test_exprs.py b/tests/query_test/test_exprs.py
index 6c82df4..d054704 100644
--- a/tests/query_test/test_exprs.py
+++ b/tests/query_test/test_exprs.py
@@ -18,6 +18,7 @@
 # Validates limit on scan nodes
 
 import pytest
+from random import randint
 
 from tests.common.impala_test_suite import ImpalaTestSuite
 from tests.common.test_dimensions import create_exec_option_dimension
@@ -119,6 +120,33 @@ class TestExprLimits(ImpalaTestSuite):
     cast_query = "select " + self.__gen_deep_func_expr("cast(", "1", " as int)")
     self.__exec_query(cast_query)
 
+  def test_huge_case(self):
+    """ Test that huge case statement can be codegen'd successfully. """
+    # Make sure case isn't top-level expression - top-level CASE is not codegen'd
+    # because of IMPALA-4356.
+    case = self.__gen_huge_case("int_col", 50, 2, "  ")
+    query = "select {0} = 42 as huge_case from functional_parquet.alltypes".format(case)
+    self.__exec_query(query)
+
+  def __gen_huge_case(self, col_name, fanout, depth, indent):
+    toks = ["case\n"]
+    for i in xrange(fanout):
+      add = randint(1, 1000000)
+      divisor = randint(1, 10000000)
+      mod = randint(0, divisor)
+      # Generate a mathematical expr that can't be easily optimised out.
+      when_expr = "{0} + {1} % {2} = {3}".format(col_name, add, divisor, mod)
+      if depth == 0:
+        then_expr = "{0}".format(i)
+      else:
+        then_expr = "({0})".format(
+            self.__gen_huge_case(col_name, fanout, depth - 1, indent + "  "))
+      toks.append(indent)
+      toks.append("when {0} then {1}\n".format(when_expr, then_expr))
+    toks.append(indent)
+    toks.append("end")
+    return ''.join(toks)
+
   def __gen_deep_infix_expr(self, prefix, repeat_suffix):
     expr = prefix
     for i in xrange(self.EXPR_DEPTH_LIMIT - 1):
@@ -140,3 +168,4 @@ class TestExprLimits(ImpalaTestSuite):
       assert impala_ret.success, "Failed to execute query %s" % (sql_str)
     except: # consider any exception a failure
       assert False, "Failed to execute query %s" % (sql_str)
+