-
On 2026-03-16 Mo 5:20 AM, Peter Eisentraut wrote:
SQL Property Graph Queries (SQL/PGQ)
Implementation of SQL property graph queries, according to SQL/PGQ
standard (ISO/IEC 9075-16:2023).
This adds:
- GRAPH_TABLE table function for graph pattern matching
- DDL commands CREATE/ALTER/DROP PROPERTY GRAPH
- several new system catalogs and information schema views
- psql \dG command
- pg_get_propgraphdef() function for pg_dump and psql
A property graph is a relation with a new relkind RELKIND_PROPGRAPH.
It acts like a view in many ways. It is rewritten to a standard
relational query in the rewriter. Access privileges act similar to a
security invoker view. (The security definer variant is not currently
implemented.)
Starting documentation can be found in doc/src/sgml/ddl.sgml and
doc/src/sgml/queries.sgml.
The output of make_propgraphdef_labels() is not stable in the face of an
upgrade which will not preserve the OID sort of the labels. The explains
the failure at
<https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=crake&dt=2026-03-16%2009%3A27%3A04&stg=xversion-upgrade-HEAD-HEAD>.
I think we need to sort the labels by name, along the lines of the
attached. Or else teach the binary upgrade code to use the same labels,
as we do for some other things. Not sure how possible that is, nor how
worth it.
We also need to fence the dependency check in pg_dump.c (also in the
attached patch)
cheers
andrew
--
Andrew Dunstan
EDB: https://www.enterprisedb.com
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 153a92fd3ea..00990b33859 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -330,6 +330,13 @@ typedef struct
typedef void (*rsv_callback) (Node *node, deparse_context *context,
void *callback_arg);
+/* Used by make_propgraphdef_labels to sort labels by name */
+typedef struct
+{
+ const char *labelname;
+ Oid ellabelid; /* pg_propgraph_element_label OID */
+} PropGraphLabelEntry;
+
/* ----------
* Global data
@@ -368,6 +375,7 @@ static char *pg_get_indexdef_worker(Oid indexrelid, int colno,
int prettyFlags, bool missing_ok);
static void make_propgraphdef_elements(StringInfo buf, Oid pgrelid, char pgekind);
static void make_propgraphdef_labels(StringInfo buf, Oid elid, const char *elalias, Oid elrelid);
+static int labelentry_name_cmp(const void *a, const void *b);
static void make_propgraphdef_properties(StringInfo buf, Oid ellabelid, Oid elrelid);
static char *pg_get_statisticsobj_worker(Oid statextid, bool columns_only,
bool missing_ok);
@@ -1776,14 +1784,28 @@ make_propgraphdef_elements(StringInfo buf, Oid pgrelid, char pgekind)
* Generates label and properties list. Pass in the element OID, the element
* alias, and the graph relation OID. Result is appended to buf.
*/
+/*
+ * Comparison function for qsort: sort label entries by label name.
+ */
+static int
+labelentry_name_cmp(const void *a, const void *b)
+{
+ const PropGraphLabelEntry *la = (const PropGraphLabelEntry *) a;
+ const PropGraphLabelEntry *lb = (const PropGraphLabelEntry *) b;
+
+ return strcmp(la->labelname, lb->labelname);
+}
+
static void
make_propgraphdef_labels(StringInfo buf, Oid elid, const char *elalias, Oid elrelid)
{
Relation pglrel;
ScanKeyData scankey[1];
SysScanDesc scan;
- int count;
HeapTuple tup;
+ PropGraphLabelEntry *labels;
+ int nlabels = 0;
+ int maxlabels = 8;
pglrel = table_open(PropgraphElementLabelRelationId, AccessShareLock);
@@ -1792,38 +1814,48 @@ make_propgraphdef_labels(StringInfo buf, Oid elid, const char *elalias, Oid elre
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(elid));
- count = 0;
- scan = systable_beginscan(pglrel, PropgraphElementLabelElementLabelIndexId, true, NULL, 1, scankey);
- while ((tup = systable_getnext(scan)))
- {
- count++;
- }
- systable_endscan(scan);
+ /*
+ * Collect all labels first so we can sort them by name, ensuring a
+ * deterministic output order regardless of catalog OID assignment.
+ */
+ labels = palloc(maxlabels * sizeof(PropGraphLabelEntry));
scan = systable_beginscan(pglrel, PropgraphElementLabelElementLabelIndexId, true, NULL, 1, scankey);
-
while ((tup = systable_getnext(scan)))
{
Form_pg_propgraph_element_label pgelform = (Form_pg_propgraph_element_label) GETSTRUCT(tup);
- const char *labelname;
- labelname = get_propgraph_label_name(pgelform->pgellabelid);
+ if (nlabels >= maxlabels)
+ {
+ maxlabels *= 2;
+ labels = repalloc(labels, maxlabels * sizeof(PropGraphLabelEntry));
+ }
- if (strcmp(labelname, elalias) == 0)
+ labels[nlabels].labelname = pstrdup(get_propgraph_label_name(pgelform->pgellabelid));
+ labels[nlabels].ellabelid = pgelform->oid;
+ nlabels++;
+ }
+ systable_endscan(scan);
+
+ table_close(pglrel, AccessShareLock);
+
+ qsort(labels, nlabels, sizeof(PropGraphLabelEntry), labelentry_name_cmp);
+
+ for (int i = 0; i < nlabels; i++)
+ {
+ if (strcmp(labels[i].labelname, elalias) == 0)
{
/* If the default label is the only label, don't print anything. */
- if (count != 1)
+ if (nlabels != 1)
appendStringInfo(buf, " DEFAULT LABEL");
}
else
- appendStringInfo(buf, " LABEL %s", quote_identifier(labelname));
+ appendStringInfo(buf, " LABEL %s", quote_identifier(labels[i].labelname));
- make_propgraphdef_properties(buf, pgelform->oid, elrelid);
+ make_propgraphdef_properties(buf, labels[i].ellabelid, elrelid);
}
- systable_endscan(scan);
-
- table_close(pglrel, AccessShareLock);
+ pfree(labels);
}
/*
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index b41a3ae3db4..23af95027e6 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -20473,11 +20473,12 @@ getDependencies(Archive *fout)
* Translate dependencies of pg_propgraph_element entries into
* dependencies of their parent pg_class entry.
*/
- appendPQExpBufferStr(query, "UNION ALL\n"
- "SELECT 'pg_class'::regclass AS classid, pgepgid AS objid, refclassid, refobjid, deptype "
- "FROM pg_depend d, pg_propgraph_element pge "
- "WHERE deptype NOT IN ('p', 'e', 'i') AND "
- "classid = 'pg_propgraph_element'::regclass AND objid = pge.oid\n");
+ if (fout->remoteVersion >= 190000)
+ appendPQExpBufferStr(query, "UNION ALL\n"
+ "SELECT 'pg_class'::regclass AS classid, pgepgid AS objid, refclassid, refobjid, deptype "
+ "FROM pg_depend d, pg_propgraph_element pge "
+ "WHERE deptype NOT IN ('p', 'e', 'i') AND "
+ "classid = 'pg_propgraph_element'::regclass AND objid = pge.oid\n");
/* Sort the output for efficiency below */
appendPQExpBufferStr(query, "ORDER BY 1,2");
