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* pgsql: Fix const-folding of JSON constructors inside a simple CASE
@ 2026-09-14 08:09 Richard Guo <rguo@postgresql.org>
0 siblings, 0 replies; 5+ messages in thread
From: Richard Guo @ 2026-09-14 08:09 UTC (permalink / raw)
To: pgsql-committers@lists.postgresql.org
Fix const-folding of JSON constructors inside a simple CASE
A JSON constructor with a RETURNING clause uses a CaseTestExpr as the
placeholder for its result in the coercion expression. When such a
constructor appears in a WHEN clause of a simple CASE whose test
expression is a constant, eval_const_expressions substituted that
constant for the placeholder, so the coercion produced the CASE's test
value instead of the constructor's result. For instance,
CASE 'x' WHEN JSON_OBJECT('a': 'b' RETURNING text) THEN 1 ELSE 0 END
evaluated to 1.
To fix, keep case_val out of scope while simplifying the coercion, as
is already done for the elemexpr of an ArrayCoerceExpr.
Back-patch to v16, where the SQL/JSON constructor functions were
introduced.
Author: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/CAMbWs48A=VCFbteTkuCoknO1_0-Cu0aMBT0M07dm7vj1QyixDg@mail.gmail.com
Backpatch-through: 16
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/e17df18a811e082a47d68263c154ae0385cd1494
Modified Files
--------------
src/backend/optimizer/util/clauses.c | 32 +++++++++++++++++++++++++++++++-
src/include/nodes/primnodes.h | 10 +++++-----
src/test/regress/expected/sqljson.out | 7 +++++++
src/test/regress/sql/sqljson.sql | 3 +++
4 files changed, 46 insertions(+), 6 deletions(-)
^ permalink raw reply [nested|flat] 5+ messages in thread
* pgsql: Fix const-folding of JSON constructors inside a simple CASE
@ 2026-09-14 08:09 Richard Guo <rguo@postgresql.org>
0 siblings, 0 replies; 5+ messages in thread
From: Richard Guo @ 2026-09-14 08:09 UTC (permalink / raw)
To: pgsql-committers@lists.postgresql.org
Fix const-folding of JSON constructors inside a simple CASE
A JSON constructor with a RETURNING clause uses a CaseTestExpr as the
placeholder for its result in the coercion expression. When such a
constructor appears in a WHEN clause of a simple CASE whose test
expression is a constant, eval_const_expressions substituted that
constant for the placeholder, so the coercion produced the CASE's test
value instead of the constructor's result. For instance,
CASE 'x' WHEN JSON_OBJECT('a': 'b' RETURNING text) THEN 1 ELSE 0 END
evaluated to 1.
To fix, keep case_val out of scope while simplifying the coercion, as
is already done for the elemexpr of an ArrayCoerceExpr.
Back-patch to v16, where the SQL/JSON constructor functions were
introduced.
Author: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/CAMbWs48A=VCFbteTkuCoknO1_0-Cu0aMBT0M07dm7vj1QyixDg@mail.gmail.com
Backpatch-through: 16
Branch
------
REL_19_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/acd8d3e0f906b4a65d1f155a6ec62bfd623d7a5b
Modified Files
--------------
src/backend/optimizer/util/clauses.c | 32 +++++++++++++++++++++++++++++++-
src/include/nodes/primnodes.h | 10 +++++-----
src/test/regress/expected/sqljson.out | 7 +++++++
src/test/regress/sql/sqljson.sql | 3 +++
4 files changed, 46 insertions(+), 6 deletions(-)
^ permalink raw reply [nested|flat] 5+ messages in thread
* pgsql: Fix const-folding of JSON constructors inside a simple CASE
@ 2026-09-14 08:09 Richard Guo <rguo@postgresql.org>
0 siblings, 0 replies; 5+ messages in thread
From: Richard Guo @ 2026-09-14 08:09 UTC (permalink / raw)
To: pgsql-committers@lists.postgresql.org
Fix const-folding of JSON constructors inside a simple CASE
A JSON constructor with a RETURNING clause uses a CaseTestExpr as the
placeholder for its result in the coercion expression. When such a
constructor appears in a WHEN clause of a simple CASE whose test
expression is a constant, eval_const_expressions substituted that
constant for the placeholder, so the coercion produced the CASE's test
value instead of the constructor's result. For instance,
CASE 'x' WHEN JSON_OBJECT('a': 'b' RETURNING text) THEN 1 ELSE 0 END
evaluated to 1.
To fix, keep case_val out of scope while simplifying the coercion, as
is already done for the elemexpr of an ArrayCoerceExpr.
Back-patch to v16, where the SQL/JSON constructor functions were
introduced.
Author: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/CAMbWs48A=VCFbteTkuCoknO1_0-Cu0aMBT0M07dm7vj1QyixDg@mail.gmail.com
Backpatch-through: 16
Branch
------
REL_18_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/29aef0f68ac89770d8623a48d33af96530deb011
Modified Files
--------------
src/backend/optimizer/util/clauses.c | 35 ++++++++++++++++++++++++++++++++++-
src/include/nodes/primnodes.h | 10 +++++-----
src/test/regress/expected/sqljson.out | 7 +++++++
src/test/regress/sql/sqljson.sql | 3 +++
4 files changed, 49 insertions(+), 6 deletions(-)
^ permalink raw reply [nested|flat] 5+ messages in thread
* pgsql: Fix const-folding of JSON constructors inside a simple CASE
@ 2026-09-14 08:09 Richard Guo <rguo@postgresql.org>
0 siblings, 0 replies; 5+ messages in thread
From: Richard Guo @ 2026-09-14 08:09 UTC (permalink / raw)
To: pgsql-committers@lists.postgresql.org
Fix const-folding of JSON constructors inside a simple CASE
A JSON constructor with a RETURNING clause uses a CaseTestExpr as the
placeholder for its result in the coercion expression. When such a
constructor appears in a WHEN clause of a simple CASE whose test
expression is a constant, eval_const_expressions substituted that
constant for the placeholder, so the coercion produced the CASE's test
value instead of the constructor's result. For instance,
CASE 'x' WHEN JSON_OBJECT('a': 'b' RETURNING text) THEN 1 ELSE 0 END
evaluated to 1.
To fix, keep case_val out of scope while simplifying the coercion, as
is already done for the elemexpr of an ArrayCoerceExpr.
Back-patch to v16, where the SQL/JSON constructor functions were
introduced.
Author: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/CAMbWs48A=VCFbteTkuCoknO1_0-Cu0aMBT0M07dm7vj1QyixDg@mail.gmail.com
Backpatch-through: 16
Branch
------
REL_17_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/23088673d311ae274069f7147cf280ee2540aeea
Modified Files
--------------
src/backend/optimizer/util/clauses.c | 35 ++++++++++++++++++++++++++++++++++-
src/include/nodes/primnodes.h | 10 +++++-----
src/test/regress/expected/sqljson.out | 7 +++++++
src/test/regress/sql/sqljson.sql | 3 +++
4 files changed, 49 insertions(+), 6 deletions(-)
^ permalink raw reply [nested|flat] 5+ messages in thread
* pgsql: Fix const-folding of JSON constructors inside a simple CASE
@ 2026-09-14 08:09 Richard Guo <rguo@postgresql.org>
0 siblings, 0 replies; 5+ messages in thread
From: Richard Guo @ 2026-09-14 08:09 UTC (permalink / raw)
To: pgsql-committers@lists.postgresql.org
Fix const-folding of JSON constructors inside a simple CASE
A JSON constructor with a RETURNING clause uses a CaseTestExpr as the
placeholder for its result in the coercion expression. When such a
constructor appears in a WHEN clause of a simple CASE whose test
expression is a constant, eval_const_expressions substituted that
constant for the placeholder, so the coercion produced the CASE's test
value instead of the constructor's result. For instance,
CASE 'x' WHEN JSON_OBJECT('a': 'b' RETURNING text) THEN 1 ELSE 0 END
evaluated to 1.
To fix, keep case_val out of scope while simplifying the coercion, as
is already done for the elemexpr of an ArrayCoerceExpr.
Back-patch to v16, where the SQL/JSON constructor functions were
introduced.
Author: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/CAMbWs48A=VCFbteTkuCoknO1_0-Cu0aMBT0M07dm7vj1QyixDg@mail.gmail.com
Backpatch-through: 16
Branch
------
REL_16_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/27ef9097b59bbdd059194bac30708eba518ab4d4
Modified Files
--------------
src/backend/optimizer/util/clauses.c | 35 ++++++++++++++++++++++++++++++++++-
src/include/nodes/primnodes.h | 10 +++++-----
src/test/regress/expected/sqljson.out | 7 +++++++
src/test/regress/sql/sqljson.sql | 2 ++
4 files changed, 48 insertions(+), 6 deletions(-)
^ permalink raw reply [nested|flat] 5+ messages in thread
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2026-09-14 08:09 pgsql: Fix const-folding of JSON constructors inside a simple CASE Richard Guo <rguo@postgresql.org>
2026-09-14 08:09 pgsql: Fix const-folding of JSON constructors inside a simple CASE Richard Guo <rguo@postgresql.org>
2026-09-14 08:09 pgsql: Fix const-folding of JSON constructors inside a simple CASE Richard Guo <rguo@postgresql.org>
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