From 7ec1ccac5e660b1ffb026fd66dfaf02aecd96cec Mon Sep 17 00:00:00 2001
From: David Hall <david.hall@mariadb.com>
Date: Tue, 24 Jul 2018 10:16:26 -0500
Subject: [PATCH] MCOL-1472 Add switch to handle nested case

---
 dbcon/mysql/ha_calpont_execplan.cpp | 7 ++++++-
 dbcon/mysql/ha_calpont_impl_if.h    | 6 +++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/dbcon/mysql/ha_calpont_execplan.cpp b/dbcon/mysql/ha_calpont_execplan.cpp
index 6113e7ca4..42d26108c 100755
--- a/dbcon/mysql/ha_calpont_execplan.cpp
+++ b/dbcon/mysql/ha_calpont_execplan.cpp
@@ -1268,7 +1268,7 @@ bool buildPredicateItem(Item_func* ifp, gp_walk_info* gwip)
 			 ifp->functype() == Item_func::ISNOTNULL_FUNC)
 	{
 		ReturnedColumn* rhs = NULL;
-		if (!gwip->rcWorkStack.empty())
+		if (!gwip->rcWorkStack.empty() && !gwip->inCaseStmt)
 		{
 			rhs = gwip->rcWorkStack.top();
 			gwip->rcWorkStack.pop();
@@ -3267,7 +3267,12 @@ FunctionColumn* buildCaseFunction(Item_func* item, gp_walk_info& gwi, bool& nonS
 		if (funcName == "case_searched" &&
             (i < arg_offset))
 		{
+            // MCOL-1472 Nested CASE with an ISNULL predicate. We don't want the predicate 
+            // to pull off of rcWorkStack, so we set this inCaseStmt flag to tell it
+            // not to.
+            gwi.inCaseStmt = true;
 			sptp.reset(buildParseTree((Item_func*)(item->arguments()[i]), gwi, nonSupport));
+            gwi.inCaseStmt = false;
 			if (!gwi.ptWorkStack.empty() && *gwi.ptWorkStack.top()->data() == sptp->data())
 			{
 				gwi.ptWorkStack.pop();
diff --git a/dbcon/mysql/ha_calpont_impl_if.h b/dbcon/mysql/ha_calpont_impl_if.h
index 9a4fd8bd7..ab7b81034 100644
--- a/dbcon/mysql/ha_calpont_impl_if.h
+++ b/dbcon/mysql/ha_calpont_impl_if.h
@@ -147,6 +147,9 @@ struct gp_walk_info
 	int32_t recursionHWM;
 	std::stack<int32_t> rcBookMarkStack;
 
+    // Kludge for MCOL-1472
+    bool inCaseStmt;
+
 	gp_walk_info() : sessionid(0),
 				   fatalParseError(false),
 				   condPush(false),
@@ -162,7 +165,8 @@ struct gp_walk_info
 				   lastSub(0),
 				   derivedTbCnt(0),
 				   recursionLevel(-1),
-				   recursionHWM(0)
+				   recursionHWM(0),
+                   inCaseStmt(false)
 	{}
 
 	~gp_walk_info() {}