From baf42e7b4a83ce88e89ed7d551f2286e2016de1b Mon Sep 17 00:00:00 2001
From: Andrew Hutchings <andrew@linuxjedi.co.uk>
Date: Thu, 10 May 2018 18:32:22 +0100
Subject: [PATCH] MCOL-1390 Fix SUBSTRING_INDEX for negative count

If negative count number is more than the number of characters in the
string then it should always return the string.

For example if a table contains SUBSTRING_INDEX('zzz', 'z', -5) should
return 'zzz'. Before this patch it would return NULL.
---
 utils/funcexp/func_substring_index.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/utils/funcexp/func_substring_index.cpp b/utils/funcexp/func_substring_index.cpp
index e3ec80b5f..a4b9fb9a6 100644
--- a/utils/funcexp/func_substring_index.cpp
+++ b/utils/funcexp/func_substring_index.cpp
@@ -71,6 +71,9 @@ std::string Func_substring_index::getStrVal(rowgroup::Row& row,
 	if ( count > (int64_t) end )
 		return str;
 
+    if (( count < 0 ) && ((count * -1) > end))
+        return str;
+
 	string value = str;
 
 	if ( count > 0 ) {