nocfbot-0003-Empty-match-EXPLAIN-coverage.txt
text/plain
Filename: nocfbot-0003-Empty-match-EXPLAIN-coverage.txt
Type: text/plain
Part: 2
Message:
Re: Row pattern recognition
From 56ebb1ad70a152cb22d4adb60069b4625659421e Mon Sep 17 00:00:00 2001
From: Henson Choi <assam258@gmail.com>
Date: Thu, 7 May 2026 14:29:14 +0900
Subject: [PATCH 03/11] Cover RPR empty-match path with EXPLAIN tests; fix
stale XXX comments
The test_728_* cases in rpr_nfa.sql claimed (via XXX) that the visited
bitmap blocks empty iterations. In fact the NFA finds the empty
matches; window aggregates just return 0 / NULL over the length-0
frame, indistinguishable from "no match" without MATCH_NUMBER().
Replace the XXX comments with the actual behavior, and add paired
EXPLAIN ANALYZE tests in rpr_explain.sql that lock in
"NFA: 3 matched (len 0/0/0.0)" as observable regression coverage.
---
src/test/regress/expected/rpr_explain.out | 200 ++++++++++++++++++++++
src/test/regress/expected/rpr_nfa.out | 29 ++--
src/test/regress/sql/rpr_explain.sql | 116 +++++++++++++
src/test/regress/sql/rpr_nfa.sql | 29 ++--
4 files changed, 340 insertions(+), 34 deletions(-)
diff --git a/src/test/regress/expected/rpr_explain.out b/src/test/regress/expected/rpr_explain.out
index 0a049d1beba..c4516d3c756 100644
--- a/src/test/regress/expected/rpr_explain.out
+++ b/src/test/regress/expected/rpr_explain.out
@@ -2102,6 +2102,206 @@ WINDOW w AS (
-> Function Scan on generate_series s (actual rows=0.00 loops=1)
(5 rows)
+-- Empty matches (length 0): mirror the test_728_* cases in rpr_nfa.sql.
+-- Window aggregates over a length-0 frame return 0 / NULL, so the SELECT
+-- result alone cannot distinguish "no match" from "empty match"; the
+-- "NFA: N matched (len 0/0/0.0)" line in EXPLAIN is the only observable
+-- proof that the empty matches were found.
+-- (A?){0,3}: min=0, A never matches -> 3 length-0 matches
+CREATE VIEW rpr_ev_edge_empty_match_min0 AS
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){0,3})
+ DEFINE A AS FALSE
+);
+SELECT line FROM unnest(string_to_array(pg_get_viewdef('rpr_ev_edge_empty_match_min0'), E'\n')) AS line WHERE line ~ 'PATTERN';
+ line
+------------------------
+ PATTERN ((a?){0,3})
+(1 row)
+
+SELECT rpr_explain_filter('
+EXPLAIN (ANALYZE, BUFFERS OFF, COSTS OFF, TIMING OFF, SUMMARY OFF)
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){0,3})
+ DEFINE A AS FALSE
+);');
+ rpr_explain_filter
+---------------------------------------------------------------------
+ WindowAgg (actual rows=3.00 loops=1)
+ Window: w AS (ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)
+ Pattern: (a?){0,3}
+ Nav Mark Lookback: 0
+ Storage: Memory Maximum Storage: NkB
+ NFA States: 6 peak, 20 total, 4 merged
+ NFA Contexts: 2 peak, 4 total, 0 pruned
+ NFA: 3 matched (len 0/0/0.0), 0 mismatched
+ -> Function Scan on generate_series s (actual rows=3.00 loops=1)
+(9 rows)
+
+-- (A?){1,3}: min=1, one empty iteration satisfies min -> 3 length-0 matches
+CREATE VIEW rpr_ev_edge_empty_match_min1 AS
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){1,3})
+ DEFINE A AS FALSE
+);
+SELECT line FROM unnest(string_to_array(pg_get_viewdef('rpr_ev_edge_empty_match_min1'), E'\n')) AS line WHERE line ~ 'PATTERN';
+ line
+------------------------
+ PATTERN ((a?){1,3})
+(1 row)
+
+SELECT rpr_explain_filter('
+EXPLAIN (ANALYZE, BUFFERS OFF, COSTS OFF, TIMING OFF, SUMMARY OFF)
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){1,3})
+ DEFINE A AS FALSE
+);');
+ rpr_explain_filter
+---------------------------------------------------------------------
+ WindowAgg (actual rows=3.00 loops=1)
+ Window: w AS (ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)
+ Pattern: (a?){1,3}
+ Nav Mark Lookback: 0
+ Storage: Memory Maximum Storage: NkB
+ NFA States: 5 peak, 16 total, 4 merged
+ NFA Contexts: 2 peak, 4 total, 0 pruned
+ NFA: 3 matched (len 0/0/0.0), 0 mismatched
+ -> Function Scan on generate_series s (actual rows=3.00 loops=1)
+(9 rows)
+
+-- (A?){2,3}: min=2 (SQL:2016 STR06 = STRE STRE) -> 3 length-0 matches
+CREATE VIEW rpr_ev_edge_empty_match_min2 AS
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){2,3})
+ DEFINE A AS FALSE
+);
+SELECT line FROM unnest(string_to_array(pg_get_viewdef('rpr_ev_edge_empty_match_min2'), E'\n')) AS line WHERE line ~ 'PATTERN';
+ line
+------------------------
+ PATTERN ((a?){2,3})
+(1 row)
+
+SELECT rpr_explain_filter('
+EXPLAIN (ANALYZE, BUFFERS OFF, COSTS OFF, TIMING OFF, SUMMARY OFF)
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){2,3})
+ DEFINE A AS FALSE
+);');
+ rpr_explain_filter
+---------------------------------------------------------------------
+ WindowAgg (actual rows=3.00 loops=1)
+ Window: w AS (ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)
+ Pattern: (a?){2,3}
+ Nav Mark Lookback: 0
+ Storage: Memory Maximum Storage: NkB
+ NFA States: 5 peak, 16 total, 4 merged
+ NFA Contexts: 2 peak, 4 total, 0 pruned
+ NFA: 3 matched (len 0/0/0.0), 0 mismatched
+ -> Function Scan on generate_series s (actual rows=3.00 loops=1)
+(9 rows)
+
+-- (A?){2,3} mixed: rows 1-2 match A (real), rows 3-4 fall back to empty
+CREATE VIEW rpr_ev_edge_empty_match_mixed AS
+SELECT count(*) OVER w
+FROM generate_series(1, 4) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){2,3})
+ DEFINE A AS v <= 2
+);
+SELECT line FROM unnest(string_to_array(pg_get_viewdef('rpr_ev_edge_empty_match_mixed'), E'\n')) AS line WHERE line ~ 'PATTERN';
+ line
+------------------------
+ PATTERN ((a?){2,3})
+(1 row)
+
+SELECT rpr_explain_filter('
+EXPLAIN (ANALYZE, BUFFERS OFF, COSTS OFF, TIMING OFF, SUMMARY OFF)
+SELECT count(*) OVER w
+FROM generate_series(1, 4) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){2,3})
+ DEFINE A AS v <= 2
+);');
+ rpr_explain_filter
+---------------------------------------------------------------------
+ WindowAgg (actual rows=4.00 loops=1)
+ Window: w AS (ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)
+ Pattern: (a?){2,3}
+ Nav Mark Lookback: 0
+ Storage: Memory Maximum Storage: NkB
+ NFA States: 8 peak, 26 total, 5 merged
+ NFA Contexts: 4 peak, 5 total, 1 pruned
+ NFA: 3 matched (len 0/2/1.0), 0 mismatched
+ -> Function Scan on generate_series s (actual rows=4.00 loops=1)
+(9 rows)
+
+-- (A? B?){2,3}: pure empty multi-element body -> 3 length-0 matches
+CREATE VIEW rpr_ev_edge_empty_match_multi AS
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A? B?){2,3})
+ DEFINE A AS FALSE, B AS FALSE
+);
+SELECT line FROM unnest(string_to_array(pg_get_viewdef('rpr_ev_edge_empty_match_multi'), E'\n')) AS line WHERE line ~ 'PATTERN';
+ line
+---------------------------
+ PATTERN ((a? b?){2,3})
+(1 row)
+
+SELECT rpr_explain_filter('
+EXPLAIN (ANALYZE, BUFFERS OFF, COSTS OFF, TIMING OFF, SUMMARY OFF)
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A? B?){2,3})
+ DEFINE A AS FALSE, B AS FALSE
+);');
+ rpr_explain_filter
+---------------------------------------------------------------------
+ WindowAgg (actual rows=3.00 loops=1)
+ Window: w AS (ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING)
+ Pattern: (a? b?){2,3}
+ Nav Mark Lookback: 0
+ Storage: Memory Maximum Storage: NkB
+ NFA States: 6 peak, 20 total, 0 merged
+ NFA Contexts: 2 peak, 4 total, 0 pruned
+ NFA: 3 matched (len 0/0/0.0), 0 mismatched
+ -> Function Scan on generate_series s (actual rows=3.00 loops=1)
+(9 rows)
+
-- Single row
CREATE VIEW rpr_ev_edge_single_row AS
SELECT count(*) OVER w
diff --git a/src/test/regress/expected/rpr_nfa.out b/src/test/regress/expected/rpr_nfa.out
index a19b26c3b94..4cff7cfbbd7 100644
--- a/src/test/regress/expected/rpr_nfa.out
+++ b/src/test/regress/expected/rpr_nfa.out
@@ -4395,9 +4395,9 @@ WINDOW w AS (
(3 rows)
-- (A?){0,3}: min=0, nullable inner.
--- A never matches. A? matches empty, min=0 satisfied immediately.
--- Per standard: empty match expected for every row.
--- XXX: visited bitmap blocks empty iteration -> no match (same as {2,3})
+-- A never matches but A? matches empty, satisfying min=0 immediately.
+-- NFA reports 3 length-0 matches (one per row); first_value / last_value
+-- are NULL because the window frame for an empty match has no rows.
WITH test_728_min0 AS (
SELECT * FROM (VALUES
(1, ARRAY['B']),
@@ -4425,9 +4425,8 @@ WINDOW w AS (
(3 rows)
-- (A?){1,3}: min=1, nullable inner.
--- A never matches. Need 1 empty iteration to satisfy min=1.
--- Per standard: empty match expected for every row.
--- XXX: visited bitmap blocks empty iteration -> no match (same as {2,3})
+-- A never matches; one empty iteration satisfies min=1.
+-- NFA reports 3 length-0 matches; first/last_value NULL over empty frame.
WITH test_728_min1 AS (
SELECT * FROM (VALUES
(1, ARRAY['B']),
@@ -4454,11 +4453,9 @@ WINDOW w AS (
3 | {B} | |
(3 rows)
--- (A?){2,3}: min=2, nullable inner.
--- A never matches. Need 2 empty iterations to satisfy min=2.
--- Per standard: STR06=(STRE STRE) is valid for min=2.
--- Expected: empty match for every row
--- XXX: visited bitmap blocks second empty iteration -> match failure
+-- (A?){2,3}: min=2, nullable inner. Per SQL:2016 STR06 = (STRE STRE)
+-- is valid: two empty iterations satisfy min=2.
+-- NFA reports 3 length-0 matches; first/last_value NULL over empty frame.
WITH test_728_min2 AS (
SELECT * FROM (VALUES
(1, ARRAY['B']),
@@ -4486,9 +4483,8 @@ WINDOW w AS (
(3 rows)
-- (A?){2,3} mixed: some rows match A, some don't
--- Rows 1-2: A matches, greedy takes 2 -> min satisfied
--- Row 3: A doesn't match, needs 2 empty iterations for min=2
--- XXX: Row 3 fails due to visited bitmap (same as pure empty {2,3})
+-- Rows 1-2: A matches, greedy takes 2 -> min satisfied (real match)
+-- Row 3: A doesn't match, two empty iterations satisfy min=2 (length-0 match)
-- Row 4: A matches 1 real iter + 1 ff empty exit -> match 4-4
WITH test_728_min2_mixed AS (
SELECT * FROM (VALUES
@@ -4559,9 +4555,8 @@ WINDOW w AS (
6 | {B} | 6 | 6
(6 rows)
--- (A? B?){2,3}: pure empty body (nothing matches)
--- XXX: All NULL: same issue as test_728_min2 (empty match at context
--- start yields UNMATCHED via startPos-1 initial advance)
+-- (A? B?){2,3}: pure empty body (nothing matches A or B).
+-- NFA reports 3 length-0 matches; first/last_value NULL over empty frame.
WITH test_728_multi_empty AS (
SELECT * FROM (VALUES
(1, ARRAY['C']),
diff --git a/src/test/regress/sql/rpr_explain.sql b/src/test/regress/sql/rpr_explain.sql
index e123be60aea..d339a80a673 100644
--- a/src/test/regress/sql/rpr_explain.sql
+++ b/src/test/regress/sql/rpr_explain.sql
@@ -1178,6 +1178,122 @@ WINDOW w AS (
DEFINE A AS v = 1, B AS v = 2
);');
+-- Empty matches (length 0): mirror the test_728_* cases in rpr_nfa.sql.
+-- Window aggregates over a length-0 frame return 0 / NULL, so the SELECT
+-- result alone cannot distinguish "no match" from "empty match"; the
+-- "NFA: N matched (len 0/0/0.0)" line in EXPLAIN is the only observable
+-- proof that the empty matches were found.
+
+-- (A?){0,3}: min=0, A never matches -> 3 length-0 matches
+CREATE VIEW rpr_ev_edge_empty_match_min0 AS
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){0,3})
+ DEFINE A AS FALSE
+);
+SELECT line FROM unnest(string_to_array(pg_get_viewdef('rpr_ev_edge_empty_match_min0'), E'\n')) AS line WHERE line ~ 'PATTERN';
+SELECT rpr_explain_filter('
+EXPLAIN (ANALYZE, BUFFERS OFF, COSTS OFF, TIMING OFF, SUMMARY OFF)
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){0,3})
+ DEFINE A AS FALSE
+);');
+
+-- (A?){1,3}: min=1, one empty iteration satisfies min -> 3 length-0 matches
+CREATE VIEW rpr_ev_edge_empty_match_min1 AS
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){1,3})
+ DEFINE A AS FALSE
+);
+SELECT line FROM unnest(string_to_array(pg_get_viewdef('rpr_ev_edge_empty_match_min1'), E'\n')) AS line WHERE line ~ 'PATTERN';
+SELECT rpr_explain_filter('
+EXPLAIN (ANALYZE, BUFFERS OFF, COSTS OFF, TIMING OFF, SUMMARY OFF)
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){1,3})
+ DEFINE A AS FALSE
+);');
+
+-- (A?){2,3}: min=2 (SQL:2016 STR06 = STRE STRE) -> 3 length-0 matches
+CREATE VIEW rpr_ev_edge_empty_match_min2 AS
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){2,3})
+ DEFINE A AS FALSE
+);
+SELECT line FROM unnest(string_to_array(pg_get_viewdef('rpr_ev_edge_empty_match_min2'), E'\n')) AS line WHERE line ~ 'PATTERN';
+SELECT rpr_explain_filter('
+EXPLAIN (ANALYZE, BUFFERS OFF, COSTS OFF, TIMING OFF, SUMMARY OFF)
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){2,3})
+ DEFINE A AS FALSE
+);');
+
+-- (A?){2,3} mixed: rows 1-2 match A (real), rows 3-4 fall back to empty
+CREATE VIEW rpr_ev_edge_empty_match_mixed AS
+SELECT count(*) OVER w
+FROM generate_series(1, 4) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){2,3})
+ DEFINE A AS v <= 2
+);
+SELECT line FROM unnest(string_to_array(pg_get_viewdef('rpr_ev_edge_empty_match_mixed'), E'\n')) AS line WHERE line ~ 'PATTERN';
+SELECT rpr_explain_filter('
+EXPLAIN (ANALYZE, BUFFERS OFF, COSTS OFF, TIMING OFF, SUMMARY OFF)
+SELECT count(*) OVER w
+FROM generate_series(1, 4) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A?){2,3})
+ DEFINE A AS v <= 2
+);');
+
+-- (A? B?){2,3}: pure empty multi-element body -> 3 length-0 matches
+CREATE VIEW rpr_ev_edge_empty_match_multi AS
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A? B?){2,3})
+ DEFINE A AS FALSE, B AS FALSE
+);
+SELECT line FROM unnest(string_to_array(pg_get_viewdef('rpr_ev_edge_empty_match_multi'), E'\n')) AS line WHERE line ~ 'PATTERN';
+SELECT rpr_explain_filter('
+EXPLAIN (ANALYZE, BUFFERS OFF, COSTS OFF, TIMING OFF, SUMMARY OFF)
+SELECT count(*) OVER w
+FROM generate_series(1, 3) AS s(v)
+WINDOW w AS (
+ ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
+ AFTER MATCH SKIP TO NEXT ROW
+ PATTERN ((A? B?){2,3})
+ DEFINE A AS FALSE, B AS FALSE
+);');
+
-- Single row
CREATE VIEW rpr_ev_edge_single_row AS
SELECT count(*) OVER w
diff --git a/src/test/regress/sql/rpr_nfa.sql b/src/test/regress/sql/rpr_nfa.sql
index 1d27e0dc09e..29ec4a9dacb 100644
--- a/src/test/regress/sql/rpr_nfa.sql
+++ b/src/test/regress/sql/rpr_nfa.sql
@@ -3234,9 +3234,9 @@ WINDOW w AS (
);
-- (A?){0,3}: min=0, nullable inner.
--- A never matches. A? matches empty, min=0 satisfied immediately.
--- Per standard: empty match expected for every row.
--- XXX: visited bitmap blocks empty iteration -> no match (same as {2,3})
+-- A never matches but A? matches empty, satisfying min=0 immediately.
+-- NFA reports 3 length-0 matches (one per row); first_value / last_value
+-- are NULL because the window frame for an empty match has no rows.
WITH test_728_min0 AS (
SELECT * FROM (VALUES
(1, ARRAY['B']),
@@ -3258,9 +3258,8 @@ WINDOW w AS (
);
-- (A?){1,3}: min=1, nullable inner.
--- A never matches. Need 1 empty iteration to satisfy min=1.
--- Per standard: empty match expected for every row.
--- XXX: visited bitmap blocks empty iteration -> no match (same as {2,3})
+-- A never matches; one empty iteration satisfies min=1.
+-- NFA reports 3 length-0 matches; first/last_value NULL over empty frame.
WITH test_728_min1 AS (
SELECT * FROM (VALUES
(1, ARRAY['B']),
@@ -3281,11 +3280,9 @@ WINDOW w AS (
A AS 'A' = ANY(flags)
);
--- (A?){2,3}: min=2, nullable inner.
--- A never matches. Need 2 empty iterations to satisfy min=2.
--- Per standard: STR06=(STRE STRE) is valid for min=2.
--- Expected: empty match for every row
--- XXX: visited bitmap blocks second empty iteration -> match failure
+-- (A?){2,3}: min=2, nullable inner. Per SQL:2016 STR06 = (STRE STRE)
+-- is valid: two empty iterations satisfy min=2.
+-- NFA reports 3 length-0 matches; first/last_value NULL over empty frame.
WITH test_728_min2 AS (
SELECT * FROM (VALUES
(1, ARRAY['B']),
@@ -3307,9 +3304,8 @@ WINDOW w AS (
);
-- (A?){2,3} mixed: some rows match A, some don't
--- Rows 1-2: A matches, greedy takes 2 -> min satisfied
--- Row 3: A doesn't match, needs 2 empty iterations for min=2
--- XXX: Row 3 fails due to visited bitmap (same as pure empty {2,3})
+-- Rows 1-2: A matches, greedy takes 2 -> min satisfied (real match)
+-- Row 3: A doesn't match, two empty iterations satisfy min=2 (length-0 match)
-- Row 4: A matches 1 real iter + 1 ff empty exit -> match 4-4
WITH test_728_min2_mixed AS (
SELECT * FROM (VALUES
@@ -3364,9 +3360,8 @@ WINDOW w AS (
B AS 'B' = ANY(flags)
);
--- (A? B?){2,3}: pure empty body (nothing matches)
--- XXX: All NULL: same issue as test_728_min2 (empty match at context
--- start yields UNMATCHED via startPos-1 initial advance)
+-- (A? B?){2,3}: pure empty body (nothing matches A or B).
+-- NFA reports 3 length-0 matches; first/last_value NULL over empty frame.
WITH test_728_multi_empty AS (
SELECT * FROM (VALUES
(1, ARRAY['C']),
--
2.50.1 (Apple Git-155)