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help / color / mirror / Atom feedFrom: Ashutosh Bapat <[email protected]>
To: Peter Eisentraut <[email protected]>
Cc: SATYANARAYANA NARLAPURAM <[email protected]>
Cc: Junwang Zhao <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Subject: Re: [PATCH] Resolve unknown-type literals in GRAPH_TABLE COLUMNS
Date: Tue, 12 May 2026 11:50:55 +0530
Message-ID: <CAExHW5sG6f5m22viW99wgsOmAXXK9312obZJMfZjCUevM7K9rg@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <CAHg+QDcyKNWyzDoKMxiZNjv7C-wAxs8y0ZoNkOV137Y+nk3UXg@mail.gmail.com>
<CAEG8a3KTP1sX+RbPFNST4kHdeRZQR5-dd6kEihV56=K5irrhyQ@mail.gmail.com>
<CAHg+QDdzUMW4qQmywiPmVo2z3+HccFZL+mujdXbB+ghU21u7dA@mail.gmail.com>
<CAExHW5vmmAS6Vroh8W9+vmuM2ReocODRCWPqYozGSyhxCxxL+Q@mail.gmail.com>
<[email protected]>
On Mon, May 4, 2026 at 8:42 PM Peter Eisentraut <[email protected]> wrote:
>
> On 29.04.26 16:09, Ashutosh Bapat wrote:
> > On Mon, Apr 27, 2026 at 11:34 AM SATYANARAYANA NARLAPURAM
> > <[email protected]> wrote:
> >>
> >> Hi,
> >>
> >> On Sun, Apr 26, 2026 at 8:10 AM Junwang Zhao <[email protected]> wrote:
> >>>
> >>> Hi SATYANARAYANA,
> >>>
> >>> On Sun, Apr 26, 2026 at 3:53 AM SATYANARAYANA NARLAPURAM
> >>> <[email protected]> wrote:
> >>>>
> >>>> Hi hackers,
> >>>>
> >>>> transformRangeGraphTable() calls transformExpr() and
> >>>> assign_list_collations() for COLUMNS expressions but missed calling
> >>>> resolveTargetListUnknowns(). As a result, literals such as 'val1'
> >>>> in a COLUMNS clause retained type "unknown", causing failures with
> >>>> ORDER BY, UNION, and output conversions.
> >>>>
> >>>> Fix by calling resolveTargetListUnknowns() on the columns target
> >>>> list right after assign_list_collations(), similar to SELECT target lists in
> >>>> transformSelectStmt().
> >>>>
> >>>> Attached a patch to fix this, which also includes test cases to reproduce.
> >>>
> >>> I can reproduce this and the patch fixes it.
> >>>
> >>> One question: why is resolveTargetListUnknowns called after
> >>> assign_list_collations?
> >>>
> >>> I'm asking because in transformSelectStmt, resolveTargetListUnknowns
> >>> is invoked before assign_query_collations. It might not matter, but keeping
> >>> the order consistent would be good for readers.
> >>
> >>
> >> Updated the patch. It should be before.
> >
> > Do we really need a test for ORDER BY on a literal column? I replaced
> > all the test queries with a single one which covers all the scenarios
> > covered by those queries.
> >
> > The patch needed to consider pstate->p_resolve_unknowns. Unknown
> > literals are not resolved as text always. See the test query.
>
> I couldn't find a commit to apply this patch cleanly (the subject says
> patch 5/5, so maybe you had some unpublished local changes?).
I am maintaining all the SQL/PGQ fixes in the same branch and creating
patches from that branch. Hence 5/5. But still it shouldn't have
applied cleanly. Both git cherry-pick and git am <attached patch
file>, on a fresh branch succeeded. Please let me know if you still
face the issue.
> After
> applying the test case manually, it looks like the test output is
> already correct without the code change. So if this patch is still
> required, we need a better test case.
>
Yes, the test query doesn't reproduce the bug. Actually all but only
two queries from the Satya's patch show the bug. I have included a
test query which fails, with expected error message, without code
changes now. Also I don't think we need a separate section for this
test query. Included the query in one of the earliest sections in the
file.
--
Best Wishes,
Ashutosh Bapat
Attachments:
[text/x-patch] v20260512-0001-Resolve-unknown-type-literals-in-GRAPH_TAB.patch (3.8K, 2-v20260512-0001-Resolve-unknown-type-literals-in-GRAPH_TAB.patch)
download | inline diff:
From 69fcbf2b907ff83aaa17593c5596e495cc0720e7 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <[email protected]>
Date: Wed, 29 Apr 2026 19:07:13 +0530
Subject: [PATCH v20260512 4/4] Resolve unknown-type literals in GRAPH_TABLE
COLUMNS
The unknown-type literals in the COLUMNS clause of a GRAPH_TABLE are now
resolved to the appropriate types, causing various failures. Call
resolveTargetListUnknowns() on the columns targetlist to resolve unknonw type
literals. Do this before assigning collations so that the resolved types are
used for collations assignment.
Reported by: Satya Narlapuram <[email protected]>
Author: Satya Narlapuram <[email protected]>
Author: Ashutosh Bapat <[email protected]>
Reviewed by: Junwang Zhao <[email protected]>
Discussion: https://www.postgresql.org/message-id/CAHg+QDcyKNWyzDoKMxiZNjv7C-wAxs8y0ZoNkOV137Y+nk3UXg@mail.gmail.com
---
src/backend/parser/parse_clause.c | 4 ++++
src/test/regress/expected/graph_table.out | 9 +++++++++
src/test/regress/sql/graph_table.sql | 2 ++
3 files changed, 15 insertions(+)
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
index 4270c2382c4..3d0585b8efb 100644
--- a/src/backend/parser/parse_clause.c
+++ b/src/backend/parser/parse_clause.c
@@ -1003,6 +1003,10 @@ transformRangeGraphTable(ParseState *pstate, RangeGraphTable *rgt)
columns = lappend(columns, te);
}
+ /* resolve any still-unresolved output columns as being type text */
+ if (pstate->p_resolve_unknowns)
+ resolveTargetListUnknowns(pstate, columns);
+
/*
* Assign collations to column expressions now since
* assign_query_collations() does not process rangetable entries.
diff --git a/src/test/regress/expected/graph_table.out b/src/test/regress/expected/graph_table.out
index cc6d80afd82..e8d49fd5cd4 100644
--- a/src/test/regress/expected/graph_table.out
+++ b/src/test/regress/expected/graph_table.out
@@ -160,6 +160,15 @@ SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers) COLUMNS (c.name));
customer3
(3 rows)
+-- Unknown type resolution
+SELECT *, pg_typeof(unknown_col) AS unknown_col_type, pg_typeof(null_col) AS null_col_type FROM GRAPH_TABLE (myshop MATCH (c IS customers) COLUMNS (c.name, 'unknown-literal' AS unknown_col, NULL AS null_col));
+ name | unknown_col | null_col | unknown_col_type | null_col_type
+-----------+-----------------+----------+------------------+---------------
+ customer1 | unknown-literal | | text | text
+ customer2 | unknown-literal | | text | text
+ customer3 | unknown-literal | | text | text
+(3 rows)
+
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers WHERE c.address = 'US')-[IS customer_orders]->(o IS orders) COLUMNS (c.name));
name
-----------
diff --git a/src/test/regress/sql/graph_table.sql b/src/test/regress/sql/graph_table.sql
index 0e381ec72bc..e761f09e057 100644
--- a/src/test/regress/sql/graph_table.sql
+++ b/src/test/regress/sql/graph_table.sql
@@ -134,6 +134,8 @@ INSERT INTO wishlist_items (wishlist_items_id, wishlist_id, product_no) VALUES
-- single element path pattern
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers) COLUMNS (c.name));
+-- Unknown type resolution
+SELECT *, pg_typeof(unknown_col) AS unknown_col_type, pg_typeof(null_col) AS null_col_type FROM GRAPH_TABLE (myshop MATCH (c IS customers) COLUMNS (c.name, 'unknown-literal' AS unknown_col, NULL AS null_col));
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers WHERE c.address = 'US')-[IS customer_orders]->(o IS orders) COLUMNS (c.name));
-- graph element specification without label or variable
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers WHERE c.address = 'US')-[]->(o IS orders) COLUMNS (c.name AS customer_name));
--
2.34.1
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Subject: Re: [PATCH] Resolve unknown-type literals in GRAPH_TABLE COLUMNS
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