@@ -616,10 +616,10 @@ public function getBulkTableSchema(Connection $connection, array $tables): array
         // duplicate per-table queries that fetchColumns() and fetchConstraints()
         // previously issued separately.
         $nnRows = $connection->select(
-            "SELECT rel.relname AS table_name, con.conname, con.convalidated, att.attname AS column_name,
+            "SELECT rel.relname AS table_name, con.conname, con.convalidated, att.attname AS column_name, con.conislocal,
                     EXISTS (SELECT 1 FROM pg_constraint o
                              WHERE o.connamespace = con.connamespace AND o.conname = con.conname
-                               AND o.oid <> con.oid) AS shared_name
+                               AND o.oid <> con.oid AND o.conislocal) AS shared_name
              FROM pg_constraint con
              JOIN pg_class rel ON con.conrelid = rel.oid
              JOIN pg_namespace nsp ON rel.relnamespace = nsp.oid
@@ -630,6 +630,13 @@ public function getBulkTableSchema(Connection $connection, array $tables): array
         $namedNotNull  = [];
         $nnColsByTable = [];
         foreach ($nnRows as $r) {
+            // A partition's or child's NOT NULL inherited from its parent has
+            // the parent's name, and comes with the parent: it is the column's
+            // NOT NULL, as on a server before PostgreSQL 18. Nor do those
+            // copies make the parent's own name a shared one.
+            if (!$r['conislocal']) {
+                continue;
+            }
             $default = $r['table_name'] . '_' . $r['column_name'] . '_not_null';
             // A default name another constraint of the schema also has is named
             // outright: left to PostgreSQL, it picks the next free one instead
 
@@ -36,6 +36,13 @@ class CrossVersionPostgresTest extends PostgresRoundTripTestCase
         // before 15, colliculocale in 15 and 16, colllocale from 17).
         'collation' => "CREATE COLLATION vt_ci (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
                         ALTER TABLE vt ADD COLUMN folded text COLLATE vt_ci;",
+        // From PostgreSQL 18 a NOT NULL is a constraint, and a partition's is
+        // inherited under its parent's name: read as a constraint of its own,
+        // each partition, and the parent, differed from an older server.
+        'partitions' => "CREATE TABLE ev (id int, at date NOT NULL, a int NOT NULL) PARTITION BY RANGE (at);
+                         CREATE TABLE ev_2026 PARTITION OF ev FOR VALUES FROM ('2026-01-01') TO ('2027-01-01');
+                         CREATE TABLE ev_2027 PARTITION OF ev FOR VALUES FROM ('2027-01-01') TO ('2028-01-01');
+                         CREATE INDEX ev_i ON ev (id) WHERE a = 1;",
         // A view recreated for nothing had its comments set again, which
         // read as comments changed although they were identical.
         'comments' => "CREATE VIEW vt_c AS SELECT vt.id, vt.name FROM vt WHERE vt.a = 1;