From 2146f13408cdb85c738364fe8f7965209e08c6be Mon Sep 17 00:00:00 2001
From: Tom Lane
Date: Mon, 16 Jun 2014 15:55:05 -0400
Subject: 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
---
 src/test/regress/expected/rules.out | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'src/test')

diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 87870cf1af6..ca56b47618b 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2117,7 +2117,7 @@ shoe_ready| SELECT rsh.shoename,
     int4smaller(rsh.sh_avail, rsl.sl_avail) AS total_avail
    FROM shoe rsh,
     shoelace rsl
-  WHERE (((rsl.sl_color = rsh.slcolor) AND (rsl.sl_len_cm >= rsh.slminlen_cm)) AND (rsl.sl_len_cm <= rsh.slmaxlen_cm));
+  WHERE ((rsl.sl_color = rsh.slcolor) AND (rsl.sl_len_cm >= rsh.slminlen_cm) AND (rsl.sl_len_cm <= rsh.slmaxlen_cm));
 shoelace| SELECT s.sl_name,
     s.sl_avail,
     s.sl_color,
-- 
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