MIME-Version: 1.0
From: SATYANARAYANA NARLAPURAM <satyanarlapuram@gmail.com>
Date: Sat, 18 Apr 2026 00:56:19 -0700
Message-ID: 
 <CAHg+QDcLVa2iBnggkHxY4itZbXtDMfsYHEjnCUYe9hNbnxDi-w@mail.gmail.com>
Subject: Bug: pg_get_viewdef() fails on GRAPH_TABLE views with lateral column
 references
To: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
	Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
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Hi hackers,

pg_get_viewdef() fails with ERROR: bogus varlevelsup: 0 offset 0 for any
view containing a GRAPH_TABLE whose COLUMNS clause references an outer
(lateral)
table. This also breaks pg_dump and \d+ for any database containing such a
view.

Repro:

CREATE TABLE vtab (id int PRIMARY KEY, name text);
CREATE TABLE etab (eid int PRIMARY KEY,
    src int REFERENCES vtab(id), dst int REFERENCES vtab(id));
CREATE PROPERTY GRAPH g1
    VERTEX TABLES (vtab)
    EDGE TABLES (etab KEY (eid)
        SOURCE KEY (src) REFERENCES vtab(id)
        DESTINATION KEY (dst) REFERENCES vtab(id));
CREATE TABLE outer_t (val int);

CREATE VIEW v AS
  SELECT * FROM outer_t,
    GRAPH_TABLE (g1 MATCH (a IS vtab)
      COLUMNS (a.name AS src_name, outer_t.val AS oval));

pg_dump -d foo -p 5433
pg_dump: error: query failed: ERROR:  bogus varlevelsup: 0 offset 0
pg_dump: detail: Query was: SELECT
pg_catalog.pg_get_viewdef('173849'::pg_catalog.oid) AS viewdef

Problem:
deparse_context context variable declared in the case RTE_GRAPH_TABLE
shadows the function's
deparse_context *context parameter. The zeroed struct has namespaces = NIL,
so when get_rule_expr()
reaches a Var node, get_variable() sees list_length(context->namespaces) ==
0 and raises the error. Property
references are fine because GraphPropertyRef deparsing never touches
namespaces.

Fix:
Remove the shadowing local variable and pass the outer context pointer to
get_rule_expr(). Attached a patch
with a fix, additionally added a test.

Thanks,
Satya

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<div dir=3D"ltr">Hi hackers,<div><br></div><div>pg_get_viewdef() fails with=
 ERROR: bogus varlevelsup: 0 offset 0 for any<br>view containing a GRAPH_TA=
BLE whose COLUMNS clause references an outer (lateral)<br>table. This also =
breaks pg_dump and \d+ for any database containing such a<br>view.</div><di=
v><br></div><div>Repro:<br><div><br></div><div>CREATE TABLE vtab (id int PR=
IMARY KEY, name text);<br>CREATE TABLE etab (eid int PRIMARY KEY,<br>=C2=A0=
 =C2=A0 src int REFERENCES vtab(id), dst int REFERENCES vtab(id));<br>CREAT=
E PROPERTY GRAPH g1<br>=C2=A0 =C2=A0 VERTEX TABLES (vtab)<br>=C2=A0 =C2=A0 =
EDGE TABLES (etab KEY (eid)<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 SOURCE KEY (src)=
 REFERENCES vtab(id)<br>=C2=A0 =C2=A0 =C2=A0 =C2=A0 DESTINATION KEY (dst) R=
EFERENCES vtab(id));<br>CREATE TABLE outer_t (val int);<br><br>CREATE VIEW =
v AS<br>=C2=A0 SELECT * FROM outer_t,<br>=C2=A0 =C2=A0 GRAPH_TABLE (g1 MATC=
H (a IS vtab)<br>=C2=A0 =C2=A0 =C2=A0 COLUMNS (<a href=3D"http://a.name">a.=
name</a> AS src_name, outer_t.val AS oval));<br><br>pg_dump -d foo -p 5433<=
br>pg_dump: error: query failed: ERROR: =C2=A0bogus varlevelsup: 0 offset 0=
<br>pg_dump: detail: Query was: SELECT pg_catalog.pg_get_viewdef(&#39;17384=
9&#39;::pg_catalog.oid) AS viewdef</div><div><br></div><div>Problem:</div><=
div>deparse_context context variable declared in the case=C2=A0RTE_GRAPH_TA=
BLE shadows the function&#39;s=C2=A0</div><div>deparse_context *context par=
ameter. The zeroed struct has namespaces =3D NIL, so when get_rule_expr()=
=C2=A0</div><div>reaches a Var node, get_variable() sees list_length(contex=
t-&gt;namespaces) =3D=3D 0 and raises the error. Property</div>references a=
re fine because GraphPropertyRef deparsing never touches namespaces.</div><=
div><br></div><div>Fix:</div><div>Remove the shadowing local variable and p=
ass the outer context pointer to get_rule_expr(). Attached a patch</div><di=
v>with a fix, additionally added a test.</div><div><br></div><div>Thanks,</=
div><div>Satya</div><div><div><br></div></div></div>

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