Avoid recursion when processing simple lists of AND'ed or OR'ed clauses.

Since most of the system thinks AND and OR are N-argument expressions
anyway, let's have the grammar generate a representation of that form when
dealing with input like "x AND y AND z AND ...", rather than generating
a deeply-nested binary tree that just has to be flattened later by the
planner.  This avoids stack overflow in parse analysis when dealing with
queries having more than a few thousand such clauses; and in any case it
removes some rather unsightly inconsistencies, since some parts of parse
analysis were generating N-argument ANDs/ORs already.

It's still possible to get a stack overflow with weirdly parenthesized
input, such as "x AND (y AND (z AND ( ... )))", but such cases are not
mainstream usage.  The maximum depth of parenthesization is already
limited by Bison's stack in such cases, anyway, so that the limit is
probably fairly platform-independent.

Patch originally by Gurjeet Singh, heavily revised by me

2 files changed, 8 insertions, 9 deletions

diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index 5a98bfbc11e..f4999c5be03 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -3047,6 +3047,14 @@ raw_expression_tree_walker(Node *node,
 				/* operator name is deemed uninteresting */
 			}
 			break;
+		case T_BoolExpr:
+			{
+				BoolExpr   *expr = (BoolExpr *) node;
+
+				if (walker(expr->args, context))
+					return true;
+			}
+			break;
 		case T_ColumnRef:
 			/* we assume the fields contain nothing interesting */
 			break;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 11c74860070..deff33f6f71 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -2437,15 +2437,6 @@ _outAExpr(StringInfo str, const A_Expr *node)
 			appendStringInfoChar(str, ' ');
 			WRITE_NODE_FIELD(name);
 			break;
-		case AEXPR_AND:
-			appendStringInfoString(str, " AND");
-			break;
-		case AEXPR_OR:
-			appendStringInfoString(str, " OR");
-			break;
-		case AEXPR_NOT:
-			appendStringInfoString(str, " NOT");
-			break;
 		case AEXPR_OP_ANY:
 			appendStringInfoChar(str, ' ');
 			WRITE_NODE_FIELD(name);