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Disallow aggregates, window functions, and SRFs in GRAPH_TABLE COLUMNS

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The COLUMNS list of a GRAPH_TABLE query is parsed as an ordinary select
target list, which permits aggregate functions, window functions, and
set-returning functions.  GRAPH_TABLE has no machinery to evaluate them,
though: the rewriter copies the COLUMNS target list verbatim into a
freshly built subquery whose hasAggs/hasWindowFuncs/hasTargetSRFs flags
are never set, so the planner builds no Agg/WindowAgg node (and no SRF
expansion) and the Aggref/WindowFunc/SRF reaches the executor.  This
triggers an assertion failure ("ecxt_aggvalues != NULL"), or "Aggref
found in non-Agg plan node" on a non-assert build, for otherwise
parser-accepted SQL such as

    SELECT max(c) FROM GRAPH_TABLE
        (g MATCH (x IS v) COLUMNS (count(*) AS c));

Reject these constructs in transformRangeGraphTable() the same way
subqueries are already handled: save and clear pstate->p_hasAggs,
p_hasWindowFuncs, and p_hasTargetSRFs around the transformation of the
COLUMNS list, and raise a "not supported" error if any of them got set.

This is deliberately a blanket prohibition for now.  Once quantified
element patterns such as (a)->{1,5} are supported, aggregates over
property references of higher degree (e.g. count(a) or sum(a.val)) can
be allowed; at that point the check will need to inspect the aggregate
arguments rather than reject all aggregates outright.

Author: Ewan Young <kdbase.hack@gmail.com>
Reviewed-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CAON2xHOYAmYLkB2jGi6g77d6Fqv8YgOrfV-riQVf0K_7AdxD3w@mail.gmail.com
This commit is contained in:
Peter Eisentraut
2026-08-05 10:44:10 +02:00
parent 0e2fb2c8c3
commit 8ce749f8f6
3 changed files with 41 additions and 0 deletions
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30
src/backend/parser/parse_clause.c
View File

@@ -946,6 +946,9 @@ transformRangeGraphTable(ParseState *pstate, RangeGraphTable *rgt)
ListCell *lc;
int resno = 0;
bool saved_hasSublinks;
bool saved_hasAggs;
bool saved_hasWindowFuncs;
bool saved_hasTargetSRFs;
rel = parserOpenPropGraph(pstate, rgt->graph_name, AccessShareLock);
@@ -967,6 +970,13 @@ transformRangeGraphTable(ParseState *pstate, RangeGraphTable *rgt)
saved_hasSublinks = pstate->p_hasSubLinks;
pstate->p_hasSubLinks = false;
saved_hasAggs = pstate->p_hasAggs;
pstate->p_hasAggs = false;
saved_hasWindowFuncs = pstate->p_hasWindowFuncs;
pstate->p_hasWindowFuncs = false;
saved_hasTargetSRFs = pstate->p_hasTargetSRFs;
pstate->p_hasTargetSRFs = false;
gp = transformGraphPattern(pstate, rgt->graph_pattern);
/*
@@ -1031,6 +1041,26 @@ transformRangeGraphTable(ParseState *pstate, RangeGraphTable *rgt)
errmsg("subqueries within GRAPH_TABLE reference are not supported")));
pstate->p_hasSubLinks = saved_hasSublinks;
/*
* GRAPH_TABLE cannot yet evaluate aggregate, window, or set-returning
* functions in its COLUMNS list, so prohibit them for now.
*/
if (pstate->p_hasAggs)
ereport(ERROR,
errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("aggregate functions in GRAPH_TABLE COLUMNS are not supported"));
if (pstate->p_hasWindowFuncs)
ereport(ERROR,
errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("window functions in GRAPH_TABLE COLUMNS are not supported"));
if (pstate->p_hasTargetSRFs)
ereport(ERROR,
errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("set-returning functions in GRAPH_TABLE COLUMNS are not supported"));
pstate->p_hasAggs = saved_hasAggs;
pstate->p_hasWindowFuncs = saved_hasWindowFuncs;
pstate->p_hasTargetSRFs = saved_hasTargetSRFs;
return addRangeTableEntryForGraphTable(pstate, graphid, castNode(GraphPattern, gp), columns, colnames, rgt->alias, false, true);
}

7
src/test/regress/expected/graph_table.out
View File

@@ -471,6 +471,13 @@ SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers WHERE c.* IS NOT NULL)-[
ERROR: "*" not allowed here
LINE 1: ...M GRAPH_TABLE (myshop MATCH (c IS customers WHERE c.* IS NOT...
^
-- aggregate, window, and set-returning functions are not supported in COLUMNS
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers) COLUMNS (count(*) AS num));
ERROR: aggregate functions in GRAPH_TABLE COLUMNS are not supported
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers) COLUMNS (row_number() OVER () AS rn));
ERROR: window functions in GRAPH_TABLE COLUMNS are not supported
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers) COLUMNS (generate_series(1, 2) AS gs));
ERROR: set-returning functions in GRAPH_TABLE COLUMNS are not supported
-- consecutive element patterns with same kind
SELECT * FROM GRAPH_TABLE (g1 MATCH ()() COLUMNS (1 as one));
ERROR: adjacent vertex patterns are not supported

4
src/test/regress/sql/graph_table.sql
View File

@@ -306,6 +306,10 @@ SELECT * FROM GRAPH_TABLE (g1 MATCH (src IS el1 | vl1)-[conn]->(dest) COLUMNS (c
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers WHERE c.address = 'US')-[IS customer_orders]->(o IS orders) COLUMNS (c.*));
-- star anywhere else is not allowed as a property reference
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers WHERE c.* IS NOT NULL)-[IS customer_orders]->(o IS orders) COLUMNS (c.name));
-- aggregate, window, and set-returning functions are not supported in COLUMNS
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers) COLUMNS (count(*) AS num));
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers) COLUMNS (row_number() OVER () AS rn));
SELECT * FROM GRAPH_TABLE (myshop MATCH (c IS customers) COLUMNS (generate_series(1, 2) AS gs));
-- consecutive element patterns with same kind
SELECT * FROM GRAPH_TABLE (g1 MATCH ()() COLUMNS (1 as one));
SELECT * FROM GRAPH_TABLE (g1 MATCH -> COLUMNS (1 AS one));