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fix: BED-9780 fixed optional match bugs #139

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Merged
AlyaEru merged 5 commits into from
Oct 7, 2026
Merged

fix: BED-9780 fixed optional match bugs #139

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86f7b73
fix: multi-part optional matches were malfunctioning due to simplisti…
AlyaEru Oct 5, 2026
ec45cff
fix: multiple optional match was missing results
AlyaEru Oct 5, 2026
3217cc2
test: fixed tests and added a couple more
AlyaEru Oct 6, 2026
fc029e1
fix: fixed handling of leading optional match and tested
AlyaEru Oct 6, 2026
e589030
test: added integration tests to confirm fixes
AlyaEru Oct 7, 2026
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2 changes: 2 additions & 0 deletions cypher/models/pgsql/operators.go
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Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,8 @@ const (
OperatorRegexMatch Operator = "~"
OperatorAssignment Operator = "="
OperatorAdditionAssignment Operator = "+="
OperatorIsDistinctFrom Operator = "is distinct from"
OperatorIsNotDistinctFrom Operator = "is not distinct from"

OperatorCypherRegexMatch Operator = "=~"
OperatorCypherStartsWith Operator = "starts with"
Expand Down
14 changes: 13 additions & 1 deletion cypher/models/pgsql/test/translation_cases/multipart.sql
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Expand Up @@ -108,4 +108,16 @@ with s0 as (with s1 as (with recursive s2_seed(root_id) as not materialized (sel
with s0 as (with s1 as (select e0.id as e0, (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0, (n1.id, n1.kind_ids, n1.properties)::nodecomposite as n1 from edge e0 join node n0 on n0.kind_ids operator (pg_catalog.@>) array [2]::int2[] and n0.id = e0.start_id join node n1 on n1.kind_ids operator (pg_catalog.@>) array [1]::int2[] and n1.id = e0.end_id where e0.kind_id = any (array [3]::int2[])), s2 as (select s1.e0 as e0, s1.n0 as n0, s1.n1 as n1 from s1 join edge e1 on (s1.n1).id = e1.start_id join node n2 on n2.kind_ids operator (pg_catalog.@>) array [2]::int2[] and n2.id = e1.end_id where e1.kind_id = any (array [4]::int2[]) and e1.id != s1.e0) select count(s2.n0)::int8 as i0 from s2), s3 as (select e2.id as e2, s0.i0 as i0, (n3.id, n3.kind_ids, n3.properties)::nodecomposite as n3, (n4.id, n4.kind_ids, n4.properties)::nodecomposite as n4 from s0, edge e2 join node n3 on n3.id = e2.start_id join node n4 on n4.id = e2.end_id where e2.kind_id = any (array [3]::int2[]) and (s0.i0 > 5)), s4 as (select s3.e2 as e2, e3.id as e3, s3.i0 as i0, s3.n3 as n3, s3.n4 as n4, (n5.id, n5.kind_ids, n5.properties)::nodecomposite as n5 from s3 join edge e3 on (s3.n4).id = e3.start_id join node n5 on n5.id = e3.end_id where e3.kind_id = any (array [4]::int2[]) and e3.id != s3.e2) select case when (s4.n3).id is null or s4.e2 is null or (s4.n4).id is null or s4.e3 is null or (s4.n5).id is null then null else ordered_edges_to_path(s4.n3, (select coalesce(array_agg((_edge.id, _edge.start_id, _edge.end_id, _edge.kind_id, _edge.properties)::edgecomposite order by _path.ordinality), array []::edgecomposite[]) from unnest(array [s4.e2]::int8[]) with ordinality as _path(id, ordinality) join edge _edge on _edge.id = _path.id) || (select coalesce(array_agg((_edge.id, _edge.start_id, _edge.end_id, _edge.kind_id, _edge.properties)::edgecomposite order by _path.ordinality), array []::edgecomposite[]) from unnest(array [s4.e3]::int8[]) with ordinality as _path(id, ordinality) join edge _edge on _edge.id = _path.id), array [s4.n3, s4.n4, s4.n5]::nodecomposite[])::pathcomposite end as p from s4;

-- case: match (g:NodeKind1) optional match (g)<-[r:EdgeKind1]-(m:NodeKind2) with g, count(r) as memberCount where memberCount = 0 return g
with s0 as (with s1 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where n0.kind_ids operator (pg_catalog.@>) array [1]::int2[]), s2 as (select (e0.id, e0.start_id, e0.end_id, e0.kind_id, e0.properties)::edgecomposite as e0, s1.n0 as n0, (n1.id, n1.kind_ids, n1.properties)::nodecomposite as n1 from s1 join edge e0 on (s1.n0).id = e0.end_id join node n1 on n1.kind_ids operator (pg_catalog.@>) array [2]::int2[] and n1.id = e0.start_id where e0.kind_id = any (array [3]::int2[])), s3 as (select s1.n0 as n0, s2.e0 as e0, s2.n1 as n1 from s1 left outer join s2 on (s1.n0 = s2.n0)) select s3.n0 as n0, count(s3.e0)::int8 as i0 from s3 group by n0) select s0.n0 as g from s0 where (s0.i0 = 0);
with s0 as (with s1 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where n0.kind_ids operator (pg_catalog.@>) array [1]::int2[]), s2 as (select (e0.id, e0.start_id, e0.end_id, e0.kind_id, e0.properties)::edgecomposite as e0, s1.n0 as n0, (n1.id, n1.kind_ids, n1.properties)::nodecomposite as n1 from s1 join edge e0 on (s1.n0).id = e0.end_id join node n1 on n1.kind_ids operator (pg_catalog.@>) array [2]::int2[] and n1.id = e0.start_id where e0.kind_id = any (array [3]::int2[])), s3 as (select s1.n0 as n0, s2.e0 as e0, s2.n1 as n1 from s1 left outer join s2 on (s1.n0 is not distinct from s2.n0)) select s3.n0 as n0, count(s3.e0)::int8 as i0 from s3 group by n0) select s0.n0 as g from s0 where (s0.i0 = 0);

-- case: match (g:NodeKind1) optional match (g)<-[r:EdgeKind1]-(m:NodeKind2) with g, count(r) as memberCount where memberCount = 0 return g
with s0 as (with s1 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where n0.kind_ids operator (pg_catalog.@>) array [1]::int2[]), s2 as (select (e0.id, e0.start_id, e0.end_id, e0.kind_id, e0.properties)::edgecomposite as e0, s1.n0 as n0, (n1.id, n1.kind_ids, n1.properties)::nodecomposite as n1 from s1 join edge e0 on (s1.n0).id = e0.end_id join node n1 on n1.kind_ids operator (pg_catalog.@>) array [2]::int2[] and n1.id = e0.start_id where e0.kind_id = any (array [3]::int2[])), s3 as (select s1.n0 as n0, s2.e0 as e0, s2.n1 as n1 from s1 left outer join s2 on (s1.n0 is not distinct from s2.n0)) select s3.n0 as n0, count(s3.e0)::int8 as i0 from s3 group by n0) select s0.n0 as g from s0 where (s0.i0 = 0);

-- case: match (g:NodeKind1) optional match (m:NodeKind2)-[:EdgeKind1]->(g)-[:EdgeKind1]->(m2:NodeKind2) return g
with s0 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where n0.kind_ids operator (pg_catalog.@>) array [1]::int2[]), s1 as (select (e0.id, e0.start_id, e0.end_id, e0.kind_id, e0.properties)::edgecomposite as e0, s0.n0 as n0, (n1.id, n1.kind_ids, n1.properties)::nodecomposite as n1 from s0 join edge e0 on (s0.n0).id = e0.end_id join node n1 on n1.kind_ids operator (pg_catalog.@>) array [2]::int2[] and n1.id = e0.start_id where e0.kind_id = any (array [3]::int2[])), s2 as (select s1.e0 as e0, (e1.id, e1.start_id, e1.end_id, e1.kind_id, e1.properties)::edgecomposite as e1, s1.n0 as n0, s1.n1 as n1, (n2.id, n2.kind_ids, n2.properties)::nodecomposite as n2 from s1 join edge e1 on (s1.n0).id = e1.start_id join node n2 on n2.kind_ids operator (pg_catalog.@>) array [2]::int2[] and n2.id = e1.end_id where e1.kind_id = any (array [3]::int2[]) and e1.id != (s1.e0).id), s3 as (select s0.n0 as n0, s2.e0 as e0, s2.e1 as e1, s2.n1 as n1, s2.n2 as n2 from s0 left outer join s2 on (s0.n0 is not distinct from s2.n0)) select s3.n0 as g from s3;

-- case: match (g:NodeKind1) optional match (m:NodeKind2)-[:EdgeKind1]->(g) optional match (g)-[:EdgeKind1]->(m2:NodeKind2) return g
with s0 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where n0.kind_ids operator (pg_catalog.@>) array [1]::int2[]), s1 as (select (e0.id, e0.start_id, e0.end_id, e0.kind_id, e0.properties)::edgecomposite as e0, s0.n0 as n0, (n1.id, n1.kind_ids, n1.properties)::nodecomposite as n1 from s0 join edge e0 on (s0.n0).id = e0.end_id join node n1 on n1.kind_ids operator (pg_catalog.@>) array [2]::int2[] and n1.id = e0.start_id where e0.kind_id = any (array [3]::int2[])), s2 as (select s0.n0 as n0, s1.e0 as e0, s1.n1 as n1 from s0 left outer join s1 on (s0.n0 is not distinct from s1.n0)), s3 as (select s2.e0 as e0, (e1.id, e1.start_id, e1.end_id, e1.kind_id, e1.properties)::edgecomposite as e1, s2.n0 as n0, s2.n1 as n1, (n2.id, n2.kind_ids, n2.properties)::nodecomposite as n2 from s2 join edge e1 on (s2.n0).id = e1.start_id join node n2 on n2.kind_ids operator (pg_catalog.@>) array [2]::int2[] and n2.id = e1.end_id where e1.kind_id = any (array [3]::int2[])), s4 as (select s2.e0 as e0, s2.n0 as n0, s2.n1 as n1, s3.e1 as e1, s3.n2 as n2 from s2 left outer join s3 on (s2.n1 is not distinct from s3.n1) and (s2.n0 is not distinct from s3.n0) and (s2.e0 is not distinct from s3.e0)) select s4.n0 as g from s4;

-- case: optional match (g:NodeKind1) optional match (m:NodeKind2)-[:EdgeKind1]->(g)-[:EdgeKind1]->(m2:NodeKind2) return g
with s0 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where n0.kind_ids operator (pg_catalog.@>) array [1]::int2[]), s1 as (select (e0.id, e0.start_id, e0.end_id, e0.kind_id, e0.properties)::edgecomposite as e0, s0.n0 as n0, (n1.id, n1.kind_ids, n1.properties)::nodecomposite as n1 from s0 join edge e0 on (s0.n0).id = e0.end_id join node n1 on n1.kind_ids operator (pg_catalog.@>) array [2]::int2[] and n1.id = e0.start_id where e0.kind_id = any (array [3]::int2[])), s2 as (select s1.e0 as e0, (e1.id, e1.start_id, e1.end_id, e1.kind_id, e1.properties)::edgecomposite as e1, s1.n0 as n0, s1.n1 as n1, (n2.id, n2.kind_ids, n2.properties)::nodecomposite as n2 from s1 join edge e1 on (s1.n0).id = e1.start_id join node n2 on n2.kind_ids operator (pg_catalog.@>) array [2]::int2[] and n2.id = e1.end_id where e1.kind_id = any (array [3]::int2[]) and e1.id != (s1.e0).id), s3 as (select s0.n0 as n0, s2.e0 as e0, s2.e1 as e1, s2.n1 as n1, s2.n2 as n2 from s0 left outer join s2 on (s0.n0 is not distinct from s2.n0)) select s3.n0 as g from s3;
4 changes: 2 additions & 2 deletions cypher/models/pgsql/test/translation_cases/nodes.sql
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Expand Up @@ -467,13 +467,13 @@ with s0 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from
with s0 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where (((n0.properties -> E'prop') != (@__strlit0::text)::jsonb and (n0.properties -> E'prop') != (@__strlit1::text)::jsonb or (n0.properties -> E'prop') = (@__strlit1::text)::jsonb and null))) select s0.n0 as s from s0;

-- case: match (n:NodeKind1) optional match (m:NodeKind2) where m.distinguishedname = n.unknown + m.unknown return n, m
with s0 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where n0.kind_ids operator (pg_catalog.@>) array [1]::int2[]), s1 as (select s0.n0 as n0, (n1.id, n1.kind_ids, n1.properties)::nodecomposite as n1 from s0, node n1 where ((n1.properties ->> E'distinguishedname') = ((s0.n0).properties ->> E'unknown') || (n1.properties ->> E'unknown')) and n1.kind_ids operator (pg_catalog.@>) array [2]::int2[]), s2 as (select s0.n0 as n0, s1.n1 as n1 from s0 left outer join s1 on (s0.n0 = s1.n0)) select s2.n0 as n, s2.n1 as m from s2;
with s0 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where n0.kind_ids operator (pg_catalog.@>) array [1]::int2[]), s1 as (select s0.n0 as n0, (n1.id, n1.kind_ids, n1.properties)::nodecomposite as n1 from s0, node n1 where ((n1.properties ->> E'distinguishedname') = ((s0.n0).properties ->> E'unknown') || (n1.properties ->> E'unknown')) and n1.kind_ids operator (pg_catalog.@>) array [2]::int2[]), s2 as (select s0.n0 as n0, s1.n1 as n1 from s0 left outer join s1 on (s0.n0 is not distinct from s1.n0)) select s2.n0 as n, s2.n1 as m from s2;

-- case: optional match (n:NodeKind1) return n
with s0 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where n0.kind_ids operator (pg_catalog.@>) array [1]::int2[]) select s0.n0 as n from s0;

-- case: match (n:NodeKind1) optional match (m:NodeKind2) where m.distinguishedname = n.unknown + m.unknown optional match (o:NodeKind2) where o.distinguishedname <> n.otherunknown return n, m, o
with s0 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where n0.kind_ids operator (pg_catalog.@>) array [1]::int2[]), s1 as (select s0.n0 as n0, (n1.id, n1.kind_ids, n1.properties)::nodecomposite as n1 from s0, node n1 where ((n1.properties ->> E'distinguishedname') = ((s0.n0).properties ->> E'unknown') || (n1.properties ->> E'unknown')) and n1.kind_ids operator (pg_catalog.@>) array [2]::int2[]), s2 as (select s0.n0 as n0, s1.n1 as n1 from s0 left outer join s1 on (s0.n0 = s1.n0)), s3 as (select s2.n0 as n0, s2.n1 as n1, (n2.id, n2.kind_ids, n2.properties)::nodecomposite as n2 from s2, node n2 where ((n2.properties -> E'distinguishedname') <> ((s2.n0).properties -> E'otherunknown')) and n2.kind_ids operator (pg_catalog.@>) array [2]::int2[]), s4 as (select s2.n0 as n0, s2.n1 as n1, s3.n2 as n2 from s2 left outer join s3 on (s2.n1 = s3.n1) and (s2.n0 = s3.n0)) select s4.n0 as n, s4.n1 as m, s4.n2 as o from s4;
with s0 as (select (n0.id, n0.kind_ids, n0.properties)::nodecomposite as n0 from node n0 where n0.kind_ids operator (pg_catalog.@>) array [1]::int2[]), s1 as (select s0.n0 as n0, (n1.id, n1.kind_ids, n1.properties)::nodecomposite as n1 from s0, node n1 where ((n1.properties ->> E'distinguishedname') = ((s0.n0).properties ->> E'unknown') || (n1.properties ->> E'unknown')) and n1.kind_ids operator (pg_catalog.@>) array [2]::int2[]), s2 as (select s0.n0 as n0, s1.n1 as n1 from s0 left outer join s1 on (s0.n0 is not distinct from s1.n0)), s3 as (select s2.n0 as n0, s2.n1 as n1, (n2.id, n2.kind_ids, n2.properties)::nodecomposite as n2 from s2, node n2 where ((n2.properties -> E'distinguishedname') <> ((s2.n0).properties -> E'otherunknown')) and n2.kind_ids operator (pg_catalog.@>) array [2]::int2[]), s4 as (select s2.n0 as n0, s2.n1 as n1, s3.n2 as n2 from s2 left outer join s3 on (s2.n1 is not distinct from s3.n1) and (s2.n0 is not distinct from s3.n0)) select s4.n0 as n, s4.n1 as m, s4.n2 as o from s4;

-- case: match (n) where n.name = "alpha' || (SELECT inet_server_addr()::text::int) || '" return n
-- pgsql_params:{"__strlit0":"string","__strlit1":"alpha' || (SELECT inet_server_addr()::text::int) || '"}
Expand Down
19 changes: 12 additions & 7 deletions cypher/models/pgsql/translate/match.go
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,10 @@ import (
func (s *Translator) translateMatch(match *cypher.Match) error {
currentQueryPart := s.query.CurrentPart()

// Note the current frame before adding frames from the match
// so we can use this point for optional match outer joins
joinFrame := s.scope.CurrentFrame()

for _, part := range currentQueryPart.ConsumeCurrentPattern().Parts {
if !part.IsTraversal {
if err := s.translateNonTraversalPatternPart(part); err != nil {
Expand Down Expand Up @@ -41,22 +45,22 @@ func (s *Translator) translateMatch(match *cypher.Match) error {

// If there is no valid previous frame, skip translating an `OPTIONAL MATCH`/treat as plain `MATCH`
if match.Optional {
if _, hasValidPrevious := s.previousValidFrame(s.scope.CurrentFrame()); hasValidPrevious {
return s.translateOptionalMatch()
if joinFrame != nil {

@coderabbitai coderabbitai Bot Oct 6, 2026 •
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🎯 Functional Correctness | 🟠 Major | 🏗️ Heavy lift

🔎 Supported by static analysis

🏁 Script executed:

sed -n '1,130p' cypher/models/pgsql/translate/match.go
git diff 25b51512cb8854424674c4d908667588194c34a2 fc029e1bcae7e583cea3c7048883de8d4cf849ec -- cypher/models/pgsql/translate/match.go cypher/models/pgsql/test/translation_cases/multipart.sql
sed -n '190,230p' cypher/models/pgsql/translate/tracking.go

Repository: SpecterOps/DAWGS

Length of output: 17364

🏁 Script executed:

printf '%s\n' '--- previousValidFrame definitions/usages ---'
rg -n -F -- 'previousValidFrame' cypher/models/pgsql/translate
printf '%s\n' '--- frame initialization and translateMatch callers ---'
rg -n -F -- 'PushFrame()' cypher/models/pgsql/translate
rg -n -F -- 'translateMatch(' cypher/models/pgsql/translate
printf '%s\n' '--- fixture exact lines ---'
nl -ba cypher/models/pgsql/test/translation_cases/multipart.sql | sed -n '112,132p'
printf '%s\n' '--- relevant declarations in merge-base ---'
git show 25b51512cb8854424674c4d908667588194c34a2:cypher/models/pgsql/translate/match.go | nl -ba | sed -n '1,75p'
printf '%s\n' '--- previousValidFrame implementation ---'
rg -n -C 8 -F -- 'func (s *Translator) previousValidFrame' cypher/models/pgsql/translate

Repository: SpecterOps/DAWGS

Length of output: 11521

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printf '%s\n' '--- previousValidFrame and query translation ---'
nl -ba cypher/models/pgsql/translate/query.go | sed -n '1,175p'
printf '%s\n' '--- scope and frame creation ---'
nl -ba cypher/models/pgsql/translate/tracking.go | sed -n '1,105p;225,285p'
printf '%s\n' '--- match expression dispatch and translator setup ---'
nl -ba cypher/models/pgsql/translate/translator.go | sed -n '590,675p'
rg -n -C 5 -F -- 'NewScope(' cypher/models/pgsql/translate
rg -n -C 5 -F -- 'scope.PushFrame' cypher/models/pgsql/translate/translator.go cypher/models/pgsql/translate/query.go

Repository: SpecterOps/DAWGS

Length of output: 29267

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printf '%s\n' '--- translation case harness references ---'
rg -n -F -- 'translation_cases' cypher/models/pgsql
rg -n -F -- 'multipart.sql' cypher/models/pgsql
printf '%s\n' '--- test files in pgsql translation area ---'
rg --files cypher/models/pgsql/test | sed -n '1,100p'
printf '%s\n' '--- translator scope initialization and visitor flow ---'
nl -ba cypher/models/pgsql/translate/translator.go | sed -n '95,125p;660,715p'
printf '%s\n' '--- multipart fixture cases newly added in merge-base diff ---'
git diff --unified=3 25b51512cb8854424674c4d908667588194c34a2 fc029e1bcae7e583cea3c7048883de8d4cf849ec -- cypher/models/pgsql/test/translation_cases/multipart.sql | tail -n 40

Repository: SpecterOps/DAWGS

Length of output: 14054

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printf '%s\n' '--- translation case loading/comparison ---'
nl -ba cypher/models/pgsql/test/testcase.go | sed -n '320,420p'
rg -n -C 5 -F -- 'TestTranslation' cypher/models/pgsql/test
printf '%s\n' '--- non-traversal pattern lowering ---'
rg -n -C 5 -F -- 'func (s *Translator) translateNonTraversalPatternPart' cypher/models/pgsql/translate

Repository: SpecterOps/DAWGS

Length of output: 5054

🏁 Script executed:

printf '%s\n' '--- translation test assertions ---'
nl -ba cypher/models/pgsql/test/validation_integration_test.go | sed -n '77,135p'
printf '%s\n' '--- case parsing/expected SQL fields ---'
nl -ba cypher/models/pgsql/test/testcase.go | sed -n '40,150p;416,500p'

Repository: SpecterOps/DAWGS

Length of output: 6779

🏁 Script executed:

rg -n -C 8 -F -- 'func (s *TranslationTestCase) AssertLive' cypher/models/pgsql/test/testcase.go
rg -n -C 5 -F -- 'PgSQL:' cypher/models/pgsql/test/testcase.go

Repository: SpecterOps/DAWGS

Length of output: 1240

🏁 Script executed:

nl -ba cypher/models/pgsql/test/testcase.go | sed -n '150,285p'

Repository: SpecterOps/DAWGS

Length of output: 6920

🏁 Script executed:

rg -n -C 6 -F -- '.Assert(' cypher/models/pgsql/test
rg -n -C 4 -F -- 'caseFile.Load()' cypher/models/pgsql/test
nl -ba cypher/models/pgsql/test/testcase.go | sed -n '280,325p'

Repository: SpecterOps/DAWGS

Length of output: 3922

🌐 Web query:

site:neo4j.com/docs/cypher-manual/current/clauses/optional-match/ OPTIONAL MATCH no matching rows null result initial clause

💡 Result:

**If `OPTIONAL MATCH` is the first clause**, it starts from an empty input row and attempts the pattern. If nothing matches, it returns one row with `null` for the pattern variables—not zero rows. The manual’s example of an `OPTIONAL MATCH` preserving a row uses a preceding `MATCH`, but describes the same null behavior. ([neo4j.com](https://neo4j.com/docs/cypher-manual/current/clauses/optional-match/?utm_source=openai))

By contrast, a clause that returns no rows ends the query pipeline, so later clauses have no input. ([neo4j.com](https://neo4j.com/docs/cypher-manual/current/clauses/optional-match/?utm_source=openai))

Citations:

- 1: https://neo4j.com/docs/cypher-manual/current/clauses/optional-match/?utm_source=openai
- 2: https://neo4j.com/docs/cypher-manual/current/clauses/optional-match/?utm_source=openai

Preserve the null row for a leading OPTIONAL MATCH.

The new golden case at cypher/models/pgsql/test/translation_cases/multipart.sql:122-123 expects a plain scan. If no NodeKind1 matches, the scan and downstream CTEs return no rows, but Cypher requires one row with g = null.

This behavior predates the change: the merge-base previousValidFrame check also skipped optional lowering for a leading pattern. Lower the initial optional pattern from a one-row seed, or use an equivalent null-preserving plan, and update the expected SQL.

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Review comment at @cypher/models/pgsql/translate/match.go at line 48:
Update the leading OPTIONAL MATCH handling around the `joinFrame` check so it
starts from a one-row seed or equivalent null-preserving plan, producing one row
with `g = null` when no `NodeKind1` matches. Update the corresponding expected
SQL golden case to reflect the generated plan.

After applying the fix, consider running `coderabbit review --agent` for local
review. Visit https://docs.coderabbit.ai/cli?utm_source=ghpr

@AlyaEru AlyaEru Oct 6, 2026

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Filed BED-9974 for this fix

@coderabbitai coderabbitai Bot Oct 6, 2026

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@AlyaEru Thanks for filing BED-9974 for the leading OPTIONAL MATCH fix.

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return s.translateOptionalMatch(joinFrame)
}
}

return nil
}

func (s *Translator) translateOptionalMatch() error {
func (s *Translator) translateOptionalMatch(joinFrame *Frame) error {
// Building this aggregation step requires pushing another frame onto the scope
aggrFrame, err := s.scope.PushFrame()
if err != nil {
return err
}

query, err := s.buildOptionalMatchAggregationStep(aggrFrame)
query, err := s.buildOptionalMatchAggregationStep(aggrFrame, joinFrame)
if err != nil {
return err
}
Expand All @@ -83,13 +87,12 @@ func (s *Translator) translateOptionalMatch() error {

// buildOptionalMatchAggregationStep constructs a "merge" frame to insert after an `OPTIONAL MATCH`,
// which requires a subsequent "aggregation" step to collate the optional match to the initial result set.
func (s *Translator) buildOptionalMatchAggregationStep(aggregationFrame *Frame) (pgsql.Query, error) {
func (s *Translator) buildOptionalMatchAggregationStep(aggregationFrame *Frame, originFrame *Frame) (pgsql.Query, error) {
// An "aggregation" frame like this will only be triggered after an OPTIONAL MATCH, which should only
// take place AFTER `n>=1` previous MATCH expressions. To properly base the aggregation, we need to
// join to the origin frame (prior to the OPTIONAL MATCH) based on the OPTIONAL MATCH's frame.
var (
optMatchFrame = aggregationFrame.Previous
originFrame = optMatchFrame.Previous
)

// originFrame could be nil if no previous frame is defined (for ex., leading OPTIONAL MATCH, which is
Expand All @@ -103,11 +106,13 @@ func (s *Translator) buildOptionalMatchAggregationStep(aggregationFrame *Frame)
// our join anchor between the two CTEs
var joinConstraints pgsql.Expression
for _, exported := range originFrame.Exported.Slice() {
// Note using this operator will match Null=Null. This is needed to handle OPTIONAL MATCH
// correctly. It assumes exports will always have appropriate non-null join keys.
joinConstraints = pgsql.OptionalAnd(
pgsql.NewParenthetical(
pgsql.NewBinaryExpression(
pgsql.CompoundIdentifier{originFrame.Binding.Identifier, exported},
pgsql.OperatorEquals,
pgsql.OperatorIsNotDistinctFrom,
pgsql.CompoundIdentifier{optMatchFrame.Binding.Identifier, exported},
),
),
Expand Down
20 changes: 18 additions & 2 deletions integration/testdata/templates/optional_shapes.json
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -40,13 +40,15 @@
{"id": "unlinked", "kinds": ["TemplateNodeKind1"], "properties": {"name": "unlinked", "group": "optional-filter"}},
{"id": "target", "kinds": ["TemplateNodeKind2"], "properties": {"name": "target"}},
{"id": "wrong", "kinds": ["TemplateNodeKind2"], "properties": {"name": "wrong"}},
{"id": "tail", "kinds": ["TemplateNodeKind1"], "properties": {"name": "tail"}}
{"id": "tail", "kinds": ["TemplateNodeKind1"], "properties": {"name": "tail"}},
{"id": "prefiltered", "kinds": ["TemplateNodeKind2"], "properties": {"name": "prefiltered"}}
],
"edges": [
{"start_id": "linked", "end_id": "target", "kind": "TemplateEdgeKind1", "properties": {"label": "accepted"}},
{"start_id": "filtered", "end_id": "wrong", "kind": "TemplateEdgeKind1", "properties": {"label": "rejected"}},
{"start_id": "target", "end_id": "tail", "kind": "TemplateEdgeKind2", "properties": {"label": "tail"}},
{"start_id": "wrong", "end_id": "tail", "kind": "TemplateEdgeKind2", "properties": {"label": "tail"}}
{"start_id": "wrong", "end_id": "tail", "kind": "TemplateEdgeKind2", "properties": {"label": "tail"}},
{"start_id": "prefiltered", "end_id": "filtered", "kind": "TemplateEdgeKind2", "properties": {"label": "prefiltered"}}
]
},
"variants": [
Expand Down Expand Up @@ -93,6 +95,20 @@
"query": "match (a:TemplateNodeKind1) where a.group = 'optional-filter' optional match (a)-[:TemplateEdgeKind1]->(b:TemplateNodeKind2) where b.name = 'target' return a.name, count(b) order by a.name"
},
"assert": {"ordered_row_values": [["filtered", 0], ["linked", 1], ["unlinked", 0]]}
},
{
"name": "chained pattern optional",
"vars": {
"query": "match (a:TemplateNodeKind1) where a.group = 'optional-filter' optional match (a)-[:TemplateEdgeKind1]->(b:TemplateNodeKind2)-[:TemplateEdgeKind2]->(:TemplateNodeKind1) where b.name = 'target' return a.name, count(b) order by a.name"
},
"assert": {"ordered_row_values": [["filtered", 0], ["linked", 1], ["unlinked", 0]]}
},
{
"name": "second chained optional can find values when first optional did not",
"vars": {
"query": "match (a:TemplateNodeKind1) where a.group = 'optional-filter' optional match (a)-[:TemplateEdgeKind1]->(b:TemplateNodeKind2) where b.name = 'target' optional match (c)-[:TemplateEdgeKind2]->(a) return c.name, a.name, b.name order by a.name"
},
"assert": {"ordered_row_values": [["prefiltered", "filtered", null], [null, "linked", "target"], [null, "unlinked", null]]}
}
]
}
Expand Down
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