From b512f3c7ea258fea091c9351a898b248f4623bf9 Mon Sep 17 00:00:00 2001
From: Henson Choi <assam258@gmail.com>
Date: Fri, 24 Jul 2026 05:36:12 +0900
Subject: [PATCH] Raise the RPR nesting depth limit to the last representable
 depth

RPR_DEPTH_MAX was PG_UINT8_MAX - 1, one short of what RPRDepth can hold, so
a pattern nested 254 groups deep was rejected even though the depth fits.
Use PG_UINT8_MAX: the accepted maximum becomes 254 and the first rejected
depth 255, which is where the type runs out.  A pattern at the new maximum
compiles and matches, so the top value is exercised rather than reserved.

The boundary tests for it inlined two ~2000-character PATTERN literals.
Build them from repeat('(', N) and repeat('){3,7}?', N) under \set ECHO none
instead, matching the element-count boundary test already in the file.
---
 doc/src/sgml/ref/select.sgml           |  2 +-
 src/include/optimizer/rpr.h            |  4 +--
 src/test/regress/expected/rpr_base.out | 34 ++++++---------------
 src/test/regress/sql/rpr_base.sql      | 42 +++++++++++---------------
 4 files changed, 31 insertions(+), 51 deletions(-)

diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml
index cb50cc9112a..6ab970f77eb 100644
--- a/doc/src/sgml/ref/select.sgml
+++ b/doc/src/sgml/ref/select.sgml
@@ -1196,7 +1196,7 @@ DEFINE <replaceable class="parameter">definition_variable_name</replaceable> AS
     used in the <literal>PATTERN</literal> clause is 240.
     If this limit is exceeded, an error will be raised.
     Additionally, the maximum nesting depth of pattern groups
-    (parentheses) is 253 levels.
+    (parentheses) is 254 levels.
     However, pattern optimizations such as flattening nested sequences
     and simplifying nested quantifiers may reduce the effective depth,
     so this limit is rarely reached in practice.
diff --git a/src/include/optimizer/rpr.h b/src/include/optimizer/rpr.h
index 229f5784c7b..fd076c10277 100644
--- a/src/include/optimizer/rpr.h
+++ b/src/include/optimizer/rpr.h
@@ -38,8 +38,8 @@
 #define RPR_COUNT_INF		RPR_QUANTITY_INF
 #define RPR_ELEMIDX_MAX		PG_INT16_MAX	/* max pattern elements */
 #define RPR_ELEMIDX_INVALID	((RPRElemIdx) -1)	/* invalid index */
-#define RPR_DEPTH_MAX		(PG_UINT8_MAX - 1)	/* max pattern nesting depth:
-												 * 254 */
+#define RPR_DEPTH_MAX		PG_UINT8_MAX	/* max pattern nesting depth: 255,
+											 * the largest RPRDepth */
 
 /* Reserved control-element varIds (high nibble 0xF; 0xF0-0xFA spare) */
 #define RPR_VARID_BEGIN		((RPRVarId) 0xFB)	/* group begin */
diff --git a/src/test/regress/expected/rpr_base.out b/src/test/regress/expected/rpr_base.out
index 13ee5628c2e..7af2c0b7da6 100644
--- a/src/test/regress/expected/rpr_base.out
+++ b/src/test/regress/expected/rpr_base.out
@@ -8508,37 +8508,23 @@ ERROR:  too many row pattern variables
 LINE 17:              V241)
                       ^
 DETAIL:  The maximum number of row pattern variables is 240.
--- Test: Pattern nesting at maximum depth (depth 253)
--- Note: 253 nested GROUP{3,7}? quantifiers; reluctant quantifiers are not
--- subject to quantifier multiplication, so the nesting (and depth 253) is
--- preserved after optimization.
-SELECT id, val, COUNT(*) OVER w FROM rpr_errors
-WINDOW w AS (
-    ORDER BY id
-    ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
-    PATTERN ((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((A{3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?)
-    DEFINE A AS val > 0
-);
+-- Pattern nesting-depth boundary at RPR_DEPTH_MAX (255; effective maximum
+-- 254, since scanRPRPatternRecursive() rejects depth >= RPR_DEPTH_MAX).
+-- Reluctant quantifiers are not subject to quantifier multiplication, so the
+-- nesting survives optimization and still reaches the depth check.
+-- ECHO is silenced so the generated deeply nested patterns do not flood the
+-- expected output.
+--   254 nested GROUP{3,7}? -> depth 254 = maximum, accepted.
+--   255 nested GROUP{3,7}? -> depth 255 > maximum, rejected.
+\set ECHO none
  id | val | count 
 ----+-----+-------
   1 |  10 |     0
   2 |  20 |     0
 (2 rows)
 
--- Expected: Should succeed
--- Test: Pattern nesting depth exceeds maximum (depth 254)
--- Note: 254 nested GROUP{3,7}? quantifiers; reluctant quantifiers are not
--- subject to quantifier multiplication, so the nesting reaches depth 254 and
--- exceeds the limit.
-SELECT id, val, COUNT(*) OVER w FROM rpr_errors
-WINDOW w AS (
-    ORDER BY id
-    ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
-    PATTERN (((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((A{3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?)
-    DEFINE A AS val > 0
-);
 ERROR:  pattern nesting too deep
-DETAIL:  Pattern nesting depth 254 exceeds maximum 253.
+DETAIL:  Pattern nesting depth 255 exceeds maximum 254.
 DROP TABLE rpr_errors;
 -- ============================================================
 -- Basic Pattern Matching
diff --git a/src/test/regress/sql/rpr_base.sql b/src/test/regress/sql/rpr_base.sql
index f0204fbea39..d8f55cb3e0f 100644
--- a/src/test/regress/sql/rpr_base.sql
+++ b/src/test/regress/sql/rpr_base.sql
@@ -5217,30 +5217,24 @@ WINDOW w AS (
     V231 AS val > 0, V232 AS val > 0, V233 AS val > 0, V234 AS val > 0, V235 AS val > 0, V236 AS val > 0, V237 AS val > 0, V238 AS val > 0, V239 AS val > 0, V240 AS val > 0
 );
 
--- Test: Pattern nesting at maximum depth (depth 253)
--- Note: 253 nested GROUP{3,7}? quantifiers; reluctant quantifiers are not
--- subject to quantifier multiplication, so the nesting (and depth 253) is
--- preserved after optimization.
-SELECT id, val, COUNT(*) OVER w FROM rpr_errors
-WINDOW w AS (
-    ORDER BY id
-    ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
-    PATTERN ((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((A{3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?)
-    DEFINE A AS val > 0
-);
--- Expected: Should succeed
-
--- Test: Pattern nesting depth exceeds maximum (depth 254)
--- Note: 254 nested GROUP{3,7}? quantifiers; reluctant quantifiers are not
--- subject to quantifier multiplication, so the nesting reaches depth 254 and
--- exceeds the limit.
-SELECT id, val, COUNT(*) OVER w FROM rpr_errors
-WINDOW w AS (
-    ORDER BY id
-    ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
-    PATTERN (((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((A{3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?){3,7}?)
-    DEFINE A AS val > 0
-);
+-- Pattern nesting-depth boundary at RPR_DEPTH_MAX (255; effective maximum
+-- 254, since scanRPRPatternRecursive() rejects depth >= RPR_DEPTH_MAX).
+-- Reluctant quantifiers are not subject to quantifier multiplication, so the
+-- nesting survives optimization and still reaches the depth check.
+-- ECHO is silenced so the generated deeply nested patterns do not flood the
+-- expected output.
+--   254 nested GROUP{3,7}? -> depth 254 = maximum, accepted.
+--   255 nested GROUP{3,7}? -> depth 255 > maximum, rejected.
+\set ECHO none
+SELECT format($$SELECT id, val, COUNT(*) OVER w FROM rpr_errors
+  WINDOW w AS (ORDER BY id ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+  PATTERN (%sA{3,7}?%s) DEFINE A AS val > 0)$$,
+  repeat('(', 254), repeat('){3,7}?', 254)) \gexec
+SELECT format($$SELECT id, val, COUNT(*) OVER w FROM rpr_errors
+  WINDOW w AS (ORDER BY id ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+  PATTERN (%sA{3,7}?%s) DEFINE A AS val > 0)$$,
+  repeat('(', 255), repeat('){3,7}?', 255)) \gexec
+\set ECHO all
 
 DROP TABLE rpr_errors;