From 0cad3b22cc96985588487b48c6d40e8c4a9e16e7 Mon Sep 17 00:00:00 2001
From: Brian Cloutier <github@briancloutier.com>
Date: Tue, 12 Jul 2016 11:31:27 +0300
Subject: [PATCH] Simplify code and fix include guards in citus_clauses

---
 .../executor/multi_router_executor.c          |  4 +--
 .../planner/multi_router_planner.c            | 30 +++----------------
 src/backend/distributed/utils/citus_clauses.c | 18 ++---------
 src/include/distributed/citus_clauses.h       |  6 ++--
 4 files changed, 11 insertions(+), 47 deletions(-)

diff --git a/src/backend/distributed/executor/multi_router_executor.c b/src/backend/distributed/executor/multi_router_executor.c
index 21785f26a..961345a12 100644
--- a/src/backend/distributed/executor/multi_router_executor.c
+++ b/src/backend/distributed/executor/multi_router_executor.c
@@ -336,8 +336,8 @@ ExecuteTaskAndStoreResults(QueryDesc *queryDesc, Task *task,
 		DeparseShardQuery(query, task, queryStringInfo);
 		queryString = queryStringInfo->data;
 
-		elog(DEBUG4, "old query: %s", task->queryString);
-		elog(DEBUG4, "new query: %s", queryString);
+		elog(DEBUG4, "query before master evaluation: %s", task->queryString);
+		elog(DEBUG4, "query after master evaluation:  %s", queryString);
 	}
 
 	/*
diff --git a/src/backend/distributed/planner/multi_router_planner.c b/src/backend/distributed/planner/multi_router_planner.c
index be66e6067..381acd737 100644
--- a/src/backend/distributed/planner/multi_router_planner.c
+++ b/src/backend/distributed/planner/multi_router_planner.c
@@ -57,7 +57,7 @@
 #include "optimizer/planmain.h"
 
 
-typedef struct
+typedef struct WalkerState
 {
 	bool containsVar;
 	bool varArgument;
@@ -470,11 +470,9 @@ static bool
 MasterIrreducibleExpressionWalker(Node *expression, WalkerState *state)
 {
 	char volatileFlag = 0;
-	WalkerState childState;
+	WalkerState childState = {false, false, false};
 	bool containsDisallowedFunction = false;
 
-	childState.containsVar = childState.varArgument = childState.badCoalesce = false;
-
 	if (expression == NULL)
 	{
 		return false;
@@ -501,33 +499,13 @@ MasterIrreducibleExpressionWalker(Node *expression, WalkerState *state)
 
 	if (IsA(expression, CaseExpr))
 	{
-		CaseExpr *expr = (CaseExpr *) expression;
-		ListCell *temp;
-
-		/*
-		 * contain_mutable_functions doesn't know what to do with CaseWhen so we
-		 * have to break it out ourselves
-		 */
-		foreach(temp, expr->args)
-		{
-			CaseWhen *when = (CaseWhen *) lfirst(temp);
-			Assert(IsA(when, CaseWhen));
-
-			if (contain_mutable_functions((Node *) when->expr) ||
-				contain_mutable_functions((Node *) when->result))
-			{
-				state->badCoalesce = true;
-				return true;
-			}
-		}
-
-		if (contain_mutable_functions((Node *) expr->defresult))
+		if (contain_mutable_functions(expression))
 		{
 			state->badCoalesce = true;
 			return true;
 		}
 
-		return MasterIrreducibleExpressionWalker((Node *) (expr->arg), state);
+		return false;
 	}
 
 	if (IsA(expression, Var))
diff --git a/src/backend/distributed/utils/citus_clauses.c b/src/backend/distributed/utils/citus_clauses.c
index 9a93c9160..18a5c7079 100644
--- a/src/backend/distributed/utils/citus_clauses.c
+++ b/src/backend/distributed/utils/citus_clauses.c
@@ -101,8 +101,8 @@ ExecuteMasterEvaluableFunctions(Query *query)
 
 
 /*
- * Walks the expression, evaluating any STABLE or IMMUTABLE functions so long as they
- * don't reference Vars.
+ * Walks the expression evaluating any node which invokes a function as long as a Var
+ * doesn't show up in the parameter list.
  */
 static Node *
 PartiallyEvaluateExpression(Node *expression)
@@ -195,23 +195,11 @@ EvaluateNodeIfReferencesFunction(Node *expression)
 		/* structural equivalence */
 		OpExpr *expr = (OpExpr *) expression;
 
-		/* typemod is always -1? */
-
 		return (Node *) citus_evaluate_expr((Expr *) expr,
 											expr->opresulttype, -1,
 											expr->opcollid);
 	}
 
-	if (IsA(expression, DistinctExpr))
-	{
-		DistinctExpr *expr = (DistinctExpr *) expression;
-
-		return (Node *) citus_evaluate_expr((Expr *) expr,
-											expr->opresulttype,
-											exprTypmod((Node *) expr),
-											expr->opcollid);
-	}
-
 	if (IsA(expression, CoerceViaIO))
 	{
 		CoerceViaIO *expr = (CoerceViaIO *) expression;
@@ -233,7 +221,6 @@ EvaluateNodeIfReferencesFunction(Node *expression)
 
 	if (IsA(expression, ScalarArrayOpExpr))
 	{
-		/* TODO: Test this! */
 		ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) expression;
 
 		return (Node *) citus_evaluate_expr((Expr *) expr, BOOLOID, -1, InvalidOid);
@@ -241,7 +228,6 @@ EvaluateNodeIfReferencesFunction(Node *expression)
 
 	if (IsA(expression, RowCompareExpr))
 	{
-		/* TODO: Test this! */
 		RowCompareExpr *expr = (RowCompareExpr *) expression;
 
 		return (Node *) citus_evaluate_expr((Expr *) expr, BOOLOID, -1, InvalidOid);
diff --git a/src/include/distributed/citus_clauses.h b/src/include/distributed/citus_clauses.h
index acdc3e05a..29905850a 100644
--- a/src/include/distributed/citus_clauses.h
+++ b/src/include/distributed/citus_clauses.h
@@ -8,8 +8,8 @@
  *-------------------------------------------------------------------------
  */
 
-#ifndef CITUS_NODEFUNCS_H
-#define CITUS_NODEFUNCS_H
+#ifndef CITUS_CLAUSES_H
+#define CITUS_CLAUSES_H
 
 #include "nodes/nodes.h"
 #include "nodes/parsenodes.h"
@@ -17,4 +17,4 @@
 extern bool RequiresMasterEvaluation(Query *query);
 extern void ExecuteMasterEvaluableFunctions(Query *query);
 
-#endif /* CITUS_NODEFUNCS_H */
+#endif /* CITUS_CLAUSES_H */