Re: Row pattern recognition

Hi hackers,

This is the v48 fold previewed in my 2026-05-30 post: the incremental
series carried on top of v47 has been folded back, Jian He's round-3
review [1] is applied (my point-by-point reply [2]), and an in-house
static-analysis pass plus the cosmetic clean-up are now included.

Resolved since the last post:

D3. AST "absorption" rename -- Tatsuo's call. Renamed to "merging"
(nocfbot-0031).

0025 ereport style (Tatsuo, 2026-06-02) [3]: the single-row frame
rejection used the old (errcode(...)) wrapping; updated in place to the
new errcode/errmsg style. (The remaining RPR ereports are tidied up
tree-wide in nocfbot-0045.)

Deferred (unchanged):

D2. RPRContext consolidation (Jian's round-2 #1) -- folded into the
future R010 infrastructure, where a single context can back both the
R020 window implementation and R010. We agreed to defer it at the v47
stage (Tatsuo, 2026-05-31); it is not part of v48.

Attached: the v47 feature series (v47-0001..0009) rebased onto current
master, plus the full incremental series (nocfbot-0001..0068) carried
on top of it.

Base:

89eafad297a 2026-06-06 Fix tuple deforming with virtual generated
columns

Already posted (nocfbot-0001..0026): 0001..0016 went out in earlier
rounds -- 0001..0011 [4], 0012..0015 [5], and 0016 (sent at the time as
0015) [6]; the 2026-05-30 post [7] renumbered them to run contiguously and
added 0017..0026. All are rebase only and unchanged, except nocfbot-0025,
whose single-row-frame ereports were updated to the new errcode/errmsg
style (per Tatsuo; see above). Titles for reference:

nocfbot-0001 Add DEFINE non-volatile baseline to rpr_integration B9
nocfbot-0002 Unify RPR DEFINE walkers and reject volatile callees
nocfbot-0003 Cover RPR empty-match path with EXPLAIN tests; fix stale
XXX comments
nocfbot-0004 Reclassify DEFINE qualifier check and reword diagnostic to
"expression"
nocfbot-0005 Sync stale comments on DEFINE/PATTERN handling
nocfbot-0006 Add trailing commas to RPR enum definitions
nocfbot-0007 Remove optional outer parentheses from ereport() calls in
RPR files
nocfbot-0008 Add high-water mark tracking to NFA visited bitmap reset
nocfbot-0009 Document DEFINE subquery rejection as intentional
over-rejection
nocfbot-0010 Remove duplicate #include in nodeWindowAgg.c
nocfbot-0011 Normalize SQL/RPR standard references
nocfbot-0012 Add rpr_integration B7 cases for RPR in recursive query
nocfbot-0013 Reject row pattern recognition in recursive queries
nocfbot-0014 Enhance README.rpr per Tatsuo Ishii's review
nocfbot-0015 Round out README.rpr WindowAggState field coverage
nocfbot-0016 Add raw_expression_tree_walker coverage for RPR raw nodes
nocfbot-0017 Enhance README.rpr per Jian He's review
nocfbot-0018 Clarify execRPR.c comments and tighten an Assert
nocfbot-0019 Change nfa_add_state_unique signature from bool to void
nocfbot-0020 Add reluctant bounded mid-band test to rpr_nfa
nocfbot-0021 Define RPR absorption terminology in README.rpr
nocfbot-0022 Document the get_reduced_frame_status cascade invariant
nocfbot-0023 Explain the completed-head-context branch in
update_reduced_frame
nocfbot-0024 Tighten the RPR frame-boundary check from >= to ==
nocfbot-0025 Reject single-row window frame in row pattern recognition
nocfbot-0026 Remove the redundant zero check on the RPR frame ending
offset

New since the 2026-05-30 post [7] -- nocfbot-0027..0068, in series order.
These apply Jian He's round-3 review [1], an in-house static-analysis
pass, and the v48 cosmetic fold (smallest-first, A..F at the tail).
Patches that change user-visible behavior are tagged [behavior change],
except nocfbot-0042, whose narrow variable-limit change (251 -> 240) is
noted inline.

nocfbot-0027 Restore findTargetlistEntrySQL99 to static (per Tatsuo)
nocfbot-0028 Clarify RPR comments
nocfbot-0029 Rename RPR NFA constructors to make/clone
nocfbot-0030 Demote RPR nfaVisitedNWords to a local
nocfbot-0031 Rename the AST-level prefix/suffix rewrite from
"absorption" to "merging" (D3)
nocfbot-0032 Drop non-standard per-group banner labels from RPR
forward declarations
nocfbot-0033 Clarify that ExecRPRCleanupDeadContexts always frees the
failed context
nocfbot-0034 Correct stale RPR comments and document a defensive
window check

nocfbot-0035 Fix unsafe (A{n,})* quantifier flattening
[behavior change]
(A{2,})* reaches {0} UNION [2,INF); flattening to A* wrongly admits
a single A. Skip multiplication when the outer is skippable and the
child min >= 2.

nocfbot-0036 Avoid INF-valued quantifier bound in consecutive-merge
[behavior change]
The merge overflow guard used <=, letting a merged min reach the
RPR_QUANTITY_INF sentinel; tightened to <.

nocfbot-0037 Fix count slot leak in row pattern recognition absorption
[behavior change]
An absorbable leaf VAR exiting inline at max count left its shared
depth count slot dirty for the sibling group; cleared on exit, with
the count-clear policy made explicit via Asserts.

nocfbot-0038 Demote dead runtime checks in the RPR executor to
assertions

nocfbot-0039 Fix memory leak in row pattern recognition DEFINE
evaluation [behavior change]
Per-tuple DEFINE evaluation leaked into the wrong context.

nocfbot-0040 Honor reluctant quantifier for non-leading optional RPR
variables [behavior change]
Reluctant handling existed for leading VARs and groups but not for
a non-leading optional VAR routed through nfa_route_to_elem; e.g.
(B A?? C) matched A greedily. Same skip-first pattern applied.

nocfbot-0041 Reject column-less compound navigation [behavior change]
A compound nav with no column reference is now rejected at parse
time, instead of being silently accepted with a wrong result.

nocfbot-0042 Reserve the high varId nibble for RPR control elements
(the maximum pattern-variable count drops from 251 to 240)

nocfbot-0043 Generalize quantifier multiplication [behavior change]
Replaces the hand-rolled special cases for (child{p,q}){m,n} with a
general interval-contiguity test, folding cases such as
(A{2,3}){2,3} -> A{4,9} and (A+){3} -> A{3,} while leaving genuine
gaps unflattened.

nocfbot-0044 Tidy up row pattern recognition pattern compilation
nocfbot-0045 Drop redundant parentheses from row pattern recognition
ereports
nocfbot-0046 Tidy up forward declarations and helper placement
nocfbot-0047 Update the varId documentation
nocfbot-0048 Reformat the design-decisions chapter in README.rpr
nocfbot-0049 Point to the absorption-analysis docs from the RPR flag
definitions

nocfbot-0050 Fix signed-integer overflow in frame-end clamp
[behavior change]
The frame-end clamp computed frameOffset + 1 (int64) before the
overflow check, so a FOLLOWING offset near PG_INT64_MAX overflowed;
now added in two checked steps that clamp to PG_INT64_MAX.

nocfbot-0051 Rework row pattern EXPLAIN deparser to fix grouped
alternation branches [EXPLAIN output]
The bytecode deparser collapsed alternations whose branches were
quantified groups (e.g. (C | (A B)+ | D)). Rewritten as recursive
descent over depth/jump-anchored windows; display-only, execution
was already correct.

nocfbot-0052 Handle row pattern navigation nodes in exprTypmod and
isSimpleNode
nocfbot-0053 Restore the error cursor for too many row pattern
variables
nocfbot-0054 Test deparse of an inline row pattern window
nocfbot-0055 Fix a mislabeled INITIAL test

nocfbot-0056 Reject invalid column references in row pattern DEFINE
clauses [behavior change]
Outer-query correlated references and 3-part qualified names in
DEFINE were reaching an internal "Upper-level Var found where not
expected" (XX000); both now raise a clean, classified error at
transformColumnRef.

nocfbot-0057 Fix shortest match for reluctant nullable quantifiers
[behavior change]
An outer reluctant quantifier over a nullable reluctant body, e.g.
(A??)+?, consumed rows instead of taking the empty match. The
count<min branch in nfa_advance_end now mirrors its sibling and
routes the fast-forward exit first for reluctant elements.

nocfbot-0058 Compare varno when preserving DEFINE-referenced columns
[behavior change]
The allpaths DEFINE-column retention loop compared varattno only;
it now matches varno/varlevelsup too, dropping over-retention.

nocfbot-0059 Allow a row pattern quantifier with no space before the
alternation operator [behavior change]
The lexer glues "*|" etc. into one token, so (A*|B) failed. The
grammar now recognizes the glued forms via a transient trailing_alt
flag and splitRPRTrailingAlt() re-splits so "A*|B" == "A* | B".

nocfbot-0060 Fix outdated function and file references in RPR docs
nocfbot-0061 Assert that row pattern nesting depth never aliases the
RPR_DEPTH_NONE sentinel

nocfbot-0062 Invalidate the row pattern nav slot cache when a window
partition changes [behavior change]
release_partition() now resets nav_slot_pos so a stale cached slot
position cannot survive a partition boundary.

nocfbot-0063 Tidy up formatting in row pattern recognition code (A)
nocfbot-0064 Modernize idioms in row pattern recognition code (B)
nocfbot-0065 Use width-explicit integer limit macros (C)
(INT_MAX -> PG_INT32_MAX, the unbounded sentinel)
nocfbot-0066 Tidy up row pattern recognition regression test comments (D)
nocfbot-0067 Add row pattern recognition negative and coverage tests (E)
nocfbot-0068 Use foreach_node and friends in RPR code (F)
(foreach + lfirst() -> foreach_node;
foreach_current_index, dropping redundant breaks)

Issue-to-patch map (each raised issue -> decision -> landing), by source.
(Earlier incremental cleanup 0001..0016: see [4][5][6].)

Jian He, round 1 (2026-05-26):
Short-circuit optimization invited to drive -> separate series
Absorption README narrative accept -> nocfbot-0017
DFS expansion accept -> nocfbot-0017
initialAdvance README mismatch accept -> nocfbot-0017
"absorption" -> "merging" rename accept (Tatsuo) -> nocfbot-0031
Defensive Assert in advance_var accept -> nocfbot-0018
Finalize unnecessary? keep -> nocfbot-0018
Greedy comment label accept -> nocfbot-0018
state->next reset decline -> nocfbot-0018
visited marking purpose accept -> nocfbot-0018
compareDepth comment accept -> nocfbot-0018
ALT depth invariant Assert decline -> nocfbot-0018
Unused bool return accept -> nocfbot-0019
count >= 3 test coverage accept -> nocfbot-0020

Jian He, round 2 (2026-05-28):
RPRContext consolidation defer (Tatsuo) -> D2
README terminology + typo accept -> nocfbot-0021
get_reduced_frame_status order keep -> nocfbot-0022
states == NULL branch coverage already reached -> nocfbot-0023
currentPos >= -> == accept -> nocfbot-0024
single-row frame (6.10.2, D1) reject (Tatsuo) -> nocfbot-0025
ExecRPRProcessRow refactor Datum fix only -> nocfbot-0026

Jian He, round 3 (2026-05-30) [1] (reply [2]):
"Tests line N" comments rephrase -> nocfbot-0028
"at the END" wording accept -> nocfbot-0028
uppercase END cleanup accept -> nocfbot-0028
nfa_advance_var count comment reword -> nocfbot-0028
make / clone rename accept -> nocfbot-0029
nfaVisitedNWords field accept (-> local) -> nocfbot-0030
nfaStateSize field keep -> (no change)
drop the elem parameter keep -> (no change)

Jian He, off-list (2026-05-15..06-04):
Per-group banner labels drop -> nocfbot-0032
Dead-context cleanup comment clarify -> nocfbot-0033
rpr.c pg_unreachable refactor accept -> nocfbot-0044
ABSORBABLE doc pointer accept -> nocfbot-0049
has_column_ref necessity defend -> (no change)
CFI dedup decline -> (no change)
fractional FOLLOWING tests decline -> (no change)
initial/SEEK rename defer -> separate series

Tatsuo Ishii + Jian round 4 (2026-05-31..06-02):
Tatsuo README review accept -> nocfbot-0014
findTargetlistEntrySQL99 static accept -> nocfbot-0027
varId high nibble ("3") accept -> nocfbot-0042
ereport redundant parens accept -> nocfbot-0045
forward-decl / helper placement accept -> nocfbot-0046
varId documentation sync accept -> nocfbot-0047
XII chapter prose reformat reformat -> nocfbot-0048
README 0005 -> 0006 reorder at submit (Ishii) -> committer
double-free question cannot occur -> (no change)
redundant continue keep -> (no change)
non-ASCII section sign already ASCII -> (no change)
empty pattern PATTERN () R020 reject right -> (no change)

in-house static analysis:
stale comments + window check fix -> nocfbot-0034
unsafe (A{n,})* flattening fix -> nocfbot-0035
INF-valued merge bound fix -> nocfbot-0036
count slot leak fix -> nocfbot-0037
dead runtime checks -> asserts fix -> nocfbot-0038
DEFINE per-tuple memory leak fix -> nocfbot-0039
reluctant non-leading optional fix -> nocfbot-0040
column-less compound navigation fix -> nocfbot-0041
incomplete quantifier fold (EP-1) generalize -> nocfbot-0043
frame-end signed overflow fix -> nocfbot-0050
EXPLAIN deparser grouped-alt fix -> nocfbot-0051
exprTypmod / isSimpleNode nav fix -> nocfbot-0052
errpos for too-many-vars fix -> nocfbot-0053
inline-OVER deparse coverage fix -> nocfbot-0054
INITIAL test mislabel fix -> nocfbot-0055
DEFINE outer / 3-part column ref fix -> nocfbot-0056
reluctant-nullable shortest match fix -> nocfbot-0057
allpaths varno comparison fix -> nocfbot-0058
glued quantifier + alternation fix -> nocfbot-0059
nfa_advance / README references doc -> nocfbot-0060
invariant asserts / notes assert -> nocfbot-0061
nav_slot / LAST(x,0) edge cases defense -> nocfbot-0062

v48 final fold (off-list sweep + Jian round 5 v47 patch):
pure formatting fold -> nocfbot-0063
idioms (palloc_array, Max, ...) fold -> nocfbot-0064
INT_MAX -> PG_INT32_MAX sentinel fold -> nocfbot-0065
regress comment + doc hygiene fold -> nocfbot-0066
new negative / coverage tests fold -> nocfbot-0067
foreach_node + lfirst sweep fold -> nocfbot-0068

Please let me know if any of the slicing or the grouping looks off, or
if you would prefer the correctness fixes split out ahead of the
cosmetic fold.

Thanks again to Jian for the careful reading.

Best regards,
Henson

[1] Jian's review, round 3 (2026-05-30):

https://postgr.es/m/CACJufxEsaU8GQ4yeXTWhAO8VjbrZTh5CpvUqz=4a3T0Cwz44pA@mail.gmail.com

[2] My point-by-point reply to the round-3 review (2026-05-30):

https://postgr.es/m/CAAAe_zBi1dOtWb2vnwSvGwuU0-bqAOm_7dOM4u-CmukA8xaV5Q@mail.gmail.com

[3] Tatsuo's note on the 0025 ereport wrapping (2026-06-02):

https://postgr.es/m/20260602.120305.1365406908882385077.ishii@postgresql.org

[4] Earlier incremental post -- nocfbot-0001..0011 (2026-05-09):

https://postgr.es/m/CAAAe_zCL9UtiYthrSaXCmhFMK6Q3YQ6BQGgae7C9en2k=S9doA@mail.gmail.com

[5] Earlier incremental post -- nocfbot-0012..0015 (2026-05-12):

https://postgr.es/m/CAAAe_zBg7y5frYxReua1dczXkMK-7fk6bkVo5ZQXDYxpxe0cwA@mail.gmail.com

[6] nocfbot-0016, sent at the time as 0015 (2026-05-26):

https://postgr.es/m/CAAAe_zD7vCLCb+vxpO3P-NsDUZ=JcN8EGCV0dz0BNgBKsbOGcQ@mail.gmail.com

[7] The 2026-05-30 post -- renumbered 0001..0016 and added 0017..0026:

https://postgr.es/m/CAAAe_zAuHwqUfqJOD4PDUkWsxTfTytNaandq11Kddw2bfCcpvQ@mail.gmail.com