cteinline.patch

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index c1a83ca909..393c673164 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -2474,6 +2474,7 @@ _copyCommonTableExpr(const CommonTableExpr *from)
 	COPY_NODE_FIELD(ctequery);
 	COPY_LOCATION_FIELD(location);
 	COPY_SCALAR_FIELD(cterecursive);
+	COPY_SCALAR_FIELD(ctematerialized);
 	COPY_SCALAR_FIELD(cterefcount);
 	COPY_NODE_FIELD(ctecolnames);
 	COPY_NODE_FIELD(ctecoltypes);
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 7a700018e7..2112560871 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -2781,6 +2781,7 @@ _equalCommonTableExpr(const CommonTableExpr *a, const CommonTableExpr *b)
 	COMPARE_NODE_FIELD(ctequery);
 	COMPARE_LOCATION_FIELD(location);
 	COMPARE_SCALAR_FIELD(cterecursive);
+	COMPARE_SCALAR_FIELD(ctematerialized);
 	COMPARE_SCALAR_FIELD(cterefcount);
 	COMPARE_NODE_FIELD(ctecolnames);
 	COMPARE_NODE_FIELD(ctecoltypes);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 43d62062bc..2df4e6300a 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -3010,6 +3010,7 @@ _outCommonTableExpr(StringInfo str, const CommonTableExpr *node)
 	WRITE_NODE_FIELD(ctequery);
 	WRITE_LOCATION_FIELD(location);
 	WRITE_BOOL_FIELD(cterecursive);
+	WRITE_BOOL_FIELD(ctematerialized);
 	WRITE_INT_FIELD(cterefcount);
 	WRITE_NODE_FIELD(ctecolnames);
 	WRITE_NODE_FIELD(ctecoltypes);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index ccb6a1f4ac..4705ea19d7 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -404,6 +404,7 @@ _readCommonTableExpr(void)
 	READ_NODE_FIELD(ctequery);
 	READ_LOCATION_FIELD(location);
 	READ_BOOL_FIELD(cterecursive);
+	READ_BOOL_FIELD(ctematerialized);
 	READ_INT_FIELD(cterefcount);
 	READ_NODE_FIELD(ctecolnames);
 	READ_NODE_FIELD(ctecoltypes);
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 1103984779..63e5828ef9 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -1129,6 +1129,141 @@ hash_ok_operator(OpExpr *expr)
 }
 
 
+struct inline_cte_walker_ctx
+{
+	const char *ctename;
+	int levelsup;
+	int refcount;
+	Query *ctequery;
+	CommonTableExpr *cte;
+};
+
+static bool inline_cte_walker(Node *node, void *ctxp)
+{
+	struct inline_cte_walker_ctx *ctx = ctxp;
+
+	if (!node)
+		return false;
+
+	if (IsA(node, Query))
+	{
+		/*
+		 * This one is a bit tricky. It's our job to handle the recursion here,
+		 * but we do some of the lifting normally handled by query_tree_walker
+		 * in order to get the sequence of operations right.
+		 *
+		 * First, if the Query we're looking at is the one containing our CTE
+		 * definition, then we don't need to recurse into our own CTE or CTEs
+		 * that are earlier in the list than ours (since cteList has been
+		 * sorted for us into dependency order). We could check whether a
+		 * nested query is hiding ours, but that seems too much of an edge case
+		 * to be worth optimizing (the levelsup check will ensure we don't
+		 * replace any CTEs improperly). So we scan the cteList ourselves
+		 * rather than having query_tree_walker do it.
+		 *
+		 * Second, we want to walk the rangetable _before_ replacing any
+		 * RTE_CTE nodes, in order to avoid re-walking the subquery we just
+		 * inlined. (range_table_walker, if told to visit the RTE nodes at all,
+		 * visits them before their content.) So we have range_table_walker
+		 * ignore the RTE nodes themselves and only walk their contents.
+		 *
+		 * Third, we scan the rangetable for RTE_CTE nodes to replace.
+		 *
+		 * Fourth, we use query_tree_walker to find and walk the rest of the
+		 * query, telling it to ignore the rangetable and CTEs.
+		 *
+		 * Note that ctx->levelsup is -1 on entry the first time, since we need
+		 * the incremented value to be 0 when scanning the content of the query
+		 * containing the definition.
+		 */
+		Query *query = castNode(Query, node);
+		ListCell *lc;
+		bool do_replace = ctx->levelsup >= 0;
+
+		ctx->levelsup++;
+
+		foreach (lc, query->cteList)
+		{
+			CommonTableExpr *cte = lfirst_node(CommonTableExpr, lc);
+
+			if (!do_replace && strcmp(cte->ctename, ctx->ctename) == 0)
+				do_replace = true;
+			else if (do_replace)
+				inline_cte_walker(cte->ctequery, ctxp);
+		}
+
+		range_table_walker(query->rtable, inline_cte_walker, ctxp, 0);
+
+		foreach (lc, query->rtable)
+		{
+			RangeTblEntry *rte = lfirst_node(RangeTblEntry, lc);
+
+			if (rte->rtekind == RTE_CTE &&
+				strcmp(rte->ctename, ctx->ctename) == 0 &&
+				rte->ctelevelsup == ctx->levelsup)
+			{
+				Query *newquery = ctx->ctequery;
+
+				/*
+				 * We need to do some work here that view rewrite does not, and
+				 * in turn we do not do some work that view rewrite does.
+				 *
+				 * Firstly, views can't have outer references but CTEs can
+				 * (especially in the case of CTEs referencing other CTEs), so
+				 * we need to fix up all levelsup attributes inside the CTE
+				 * query.
+				 *
+				 * Secondly, views (and explicit subqueries) currently have
+				 * different behaviour w.r.t. SELECT FOR UPDATE than CTEs do. A
+				 * FOR UPDATE clause is treated as extending into views and
+				 * subqueries, but not into CTEs. We preserve this distinction
+				 * by not trying to push rowmarks into the new subquery.
+				 *
+				 * We avoid copyObject if possible because subquery processing
+				 * copies the query too.
+				 */
+				if (ctx->levelsup > 0)
+				{
+					newquery = copyObject(newquery);
+					IncrementVarSublevelsUp((Node *) newquery, ctx->levelsup, 1);
+				}
+
+				/*
+				 * Here's where we do the actual substitution.
+				 */
+				rte->rtekind = RTE_SUBQUERY;
+				rte->subquery = newquery;
+				rte->security_barrier = false;
+
+				ctx->refcount--;
+			}
+		}
+
+		query_tree_walker(query, inline_cte_walker, ctxp,
+						  QTW_IGNORE_RANGE_TABLE | QTW_IGNORE_CTE_SUBQUERIES);
+
+		ctx->levelsup--;
+
+		return false;
+	}
+
+	return expression_tree_walker(node, inline_cte_walker, ctxp);
+}
+
+static void inline_cte(PlannerInfo *root, CommonTableExpr *cte)
+{
+	struct inline_cte_walker_ctx ctx;
+	ctx.ctequery = castNode(Query, cte->ctequery);
+	ctx.ctename = cte->ctename;
+	ctx.refcount = cte->cterefcount;
+	ctx.levelsup = -1;
+	ctx.cte = cte;
+	inline_cte_walker((Node *) root->parse, &ctx);
+	/* we must replace all references */
+	Assert(ctx.refcount == 0);
+}
+
+
 /*
  * SS_process_ctes: process a query's WITH list
  *
@@ -1167,6 +1302,23 @@ SS_process_ctes(PlannerInfo *root)
 		}
 
 		/*
+		 * Consider inlining the CTE rather than planning it separately.
+		 *
+		 * XXX this likely needs some additional checks.
+		 */
+		if (cmdType == CMD_SELECT &&
+			!cte->ctematerialized &&
+			!cte->cterecursive &&
+			(castNode(Query, cte->ctequery)->rowMarks == NIL))
+		{
+			inline_cte(root, cte);
+
+			/* Make a dummy entry in cte_plan_ids */
+			root->cte_plan_ids = lappend_int(root->cte_plan_ids, -1);
+			continue;
+		}
+
+		/*
 		 * Copy the source Query node.  Probably not necessary, but let's keep
 		 * this similar to make_subplan.
 		 */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 732e5d6788..901a3a295f 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1372,6 +1372,7 @@ typedef struct CommonTableExpr
 	int			location;		/* token location, or -1 if unknown */
 	/* These fields are set during parse analysis: */
 	bool		cterecursive;	/* is this CTE actually recursive? */
+	bool		ctematerialized;	/* is this an optimization fence? */
 	int			cterefcount;	/* number of RTEs referencing this CTE
 								 * (excluding internal self-references) */
 	List	   *ctecolnames;	/* list of output column names */