Add vertex and edge composite types with direct field access optimization

- Introduce vertex and edge as pg composite types
  vertex: (id, label, properties)
  edge: (id, label, start_id, end_id, properties)
- Property access (a.name) now directly uses a.properties for
  agtype_access_operator instead of rebuilding via _agtype_build_vertex/edge
- Optimize accessor functions (id, properties, label, type, start_id, end_id)
  to use direct FieldSelect on composite types instead of agtype functions
- Add casts: vertex/edge to agtype, vertex/edge to json/jsonb
- Add eq and not eq ops for vertex/edge composite types.
- Fix label_name specific routine to use cache instead of ag_label scan
- Write/update clauses have executors strictly tied to agtype, due to which
  the variables after any write/update clause are carried forward as agtype.
- Allows users to completely skip agtype build functions and return vertex/edge
  for pure read queries.
- Change _label_name to return agtype since record comparisons are not
  allowed with cstring. Consequently, _agtype_build_vertex/edge now accept
  agtype as label.
- Fix MERGE clause type mismatch when accessing properties from previous
  MATCH clauses by wrapping columns with agtype_volatile_wrapper
  before namespace lookup.
- Update expression index in pgvector.sql, since now it uses raw properties column
  instead of _agtype_build_vertex/edge.
- Add regression tests

Assisted-by AI

Author: MuhammadTahaNaveed

age--1.6.0--y.y.y.sql

@@ -51,3 +51,223 @@ CREATE FUNCTION ag_catalog._ag_enforce_edge_uniqueness4(graphid, graphid, graphi
     STABLE
 PARALLEL SAFE
 as 'MODULE_PATHNAME';
+
+--
+-- Composite types for vertex and edge
+--
+CREATE TYPE ag_catalog.vertex AS (
+    id graphid,
+    label agtype,
+    properties agtype
+);
+
+CREATE TYPE ag_catalog.edge AS (
+    id graphid,
+    label agtype,
+    end_id graphid,
+    start_id graphid,
+    properties agtype
+);
+
+--
+-- vertex/edge to agtype cast functions
+--
+CREATE FUNCTION ag_catalog.vertex_to_agtype(vertex)
+    RETURNS agtype
+    LANGUAGE c
+    IMMUTABLE
+RETURNS NULL ON NULL INPUT
+PARALLEL SAFE
+AS 'MODULE_PATHNAME';
+
+CREATE FUNCTION ag_catalog.edge_to_agtype(edge)
+    RETURNS agtype
+    LANGUAGE c
+    IMMUTABLE
+RETURNS NULL ON NULL INPUT
+PARALLEL SAFE
+AS 'MODULE_PATHNAME';
+
+--
+-- Implicit casts from vertex/edge to agtype
+--
+CREATE CAST (vertex AS agtype)
+    WITH FUNCTION ag_catalog.vertex_to_agtype(vertex)
+AS IMPLICIT;
+
+CREATE CAST (edge AS agtype)
+    WITH FUNCTION ag_catalog.edge_to_agtype(edge)
+AS IMPLICIT;
+
+CREATE FUNCTION ag_catalog.vertex_to_json(vertex)
+    RETURNS json
+    LANGUAGE c
+    IMMUTABLE
+RETURNS NULL ON NULL INPUT
+PARALLEL SAFE
+AS 'MODULE_PATHNAME';
+
+CREATE FUNCTION ag_catalog.edge_to_json(edge)
+    RETURNS json
+    LANGUAGE c
+    IMMUTABLE
+RETURNS NULL ON NULL INPUT
+PARALLEL SAFE
+AS 'MODULE_PATHNAME';
+
+CREATE CAST (vertex AS json)
+    WITH FUNCTION ag_catalog.vertex_to_json(vertex);
+
+CREATE CAST (edge AS json)
+    WITH FUNCTION ag_catalog.edge_to_json(edge);
+
+CREATE FUNCTION ag_catalog.vertex_to_jsonb(vertex)
+    RETURNS jsonb
+    LANGUAGE c
+    IMMUTABLE
+RETURNS NULL ON NULL INPUT
+PARALLEL SAFE
+AS 'MODULE_PATHNAME';
+
+CREATE FUNCTION ag_catalog.edge_to_jsonb(edge)
+    RETURNS jsonb
+    LANGUAGE c
+    IMMUTABLE
+RETURNS NULL ON NULL INPUT
+PARALLEL SAFE
+AS 'MODULE_PATHNAME';
+
+CREATE CAST (vertex AS jsonb)
+    WITH FUNCTION ag_catalog.vertex_to_jsonb(vertex);
+
+CREATE CAST (edge AS jsonb)
+    WITH FUNCTION ag_catalog.edge_to_jsonb(edge);
+
+--
+-- Equality operators for vertex and edge (compare by id)
+--
+CREATE FUNCTION ag_catalog.vertex_eq(vertex, vertex)
+    RETURNS boolean
+    LANGUAGE sql
+    IMMUTABLE
+RETURNS NULL ON NULL INPUT
+PARALLEL SAFE
+AS $$ SELECT $1.id = $2.id $$;
+
+CREATE OPERATOR = (
+    FUNCTION = ag_catalog.vertex_eq,
+    LEFTARG = vertex,
+    RIGHTARG = vertex,
+    COMMUTATOR = =,
+    NEGATOR = <>,
+    RESTRICT = eqsel,
+    JOIN = eqjoinsel,
+    HASHES,
+    MERGES
+);
+
+CREATE FUNCTION ag_catalog.vertex_ne(vertex, vertex)
+    RETURNS boolean
+    LANGUAGE sql
+    IMMUTABLE
+RETURNS NULL ON NULL INPUT
+PARALLEL SAFE
+AS $$ SELECT $1.id <> $2.id $$;
+
+CREATE OPERATOR <> (
+    FUNCTION = ag_catalog.vertex_ne,
+    LEFTARG = vertex,
+    RIGHTARG = vertex,
+    COMMUTATOR = <>,
+    NEGATOR = =,
+    RESTRICT = neqsel,
+    JOIN = neqjoinsel
+);
+
+CREATE FUNCTION ag_catalog.edge_eq(edge, edge)
+    RETURNS boolean
+    LANGUAGE sql
+    IMMUTABLE
+RETURNS NULL ON NULL INPUT
+PARALLEL SAFE
+AS $$ SELECT $1.id = $2.id $$;
+
+CREATE OPERATOR = (
+    FUNCTION = ag_catalog.edge_eq,
+    LEFTARG = edge,
+    RIGHTARG = edge,
+    COMMUTATOR = =,
+    NEGATOR = <>,
+    RESTRICT = eqsel,
+    JOIN = eqjoinsel,
+    HASHES,
+    MERGES
+);
+
+CREATE FUNCTION ag_catalog.edge_ne(edge, edge)
+    RETURNS boolean
+    LANGUAGE sql
+    IMMUTABLE
+RETURNS NULL ON NULL INPUT
+PARALLEL SAFE
+AS $$ SELECT $1.id <> $2.id $$;
+
+CREATE OPERATOR <> (
+    FUNCTION = ag_catalog.edge_ne,
+    LEFTARG = edge,
+    RIGHTARG = edge,
+    COMMUTATOR = <>,
+    NEGATOR = =,
+    RESTRICT = neqsel,
+    JOIN = neqjoinsel
+);
+
+--
+-- Drop and recreate _label_name with new return type (cstring -> agtype)
+--
+DROP FUNCTION IF EXISTS ag_catalog._label_name(oid, graphid);
+
+CREATE FUNCTION ag_catalog._label_name(graph_oid oid, graphid)
+    RETURNS agtype
+    LANGUAGE c
+    IMMUTABLE
+PARALLEL SAFE
+AS 'MODULE_PATHNAME';
+
+--
+-- Drop and recreate _agtype_build_vertex with new signature (cstring -> agtype for label)
+--
+DROP FUNCTION IF EXISTS ag_catalog._agtype_build_vertex(graphid, cstring, agtype);
+
+CREATE FUNCTION ag_catalog._agtype_build_vertex(graphid, agtype, agtype)
+    RETURNS agtype
+    LANGUAGE c
+    IMMUTABLE
+CALLED ON NULL INPUT
+PARALLEL SAFE
+AS 'MODULE_PATHNAME';
+
+--
+-- Drop and recreate _agtype_build_edge with new signature (cstring -> agtype for label)
+--
+DROP FUNCTION IF EXISTS ag_catalog._agtype_build_edge(graphid, graphid, graphid, cstring, agtype);
+
+CREATE FUNCTION ag_catalog._agtype_build_edge(graphid, graphid, graphid,
+                                              agtype, agtype)
+    RETURNS agtype
+    LANGUAGE c
+    IMMUTABLE
+CALLED ON NULL INPUT
+PARALLEL SAFE
+AS 'MODULE_PATHNAME';
+
+--
+-- Helper function for optimized startNode/endNode
+--
+CREATE FUNCTION ag_catalog._get_vertex_by_graphid(text, graphid)
+    RETURNS agtype
+    LANGUAGE c
+    STABLE
+RETURNS NULL ON NULL INPUT
+PARALLEL SAFE
+AS 'MODULE_PATHNAME';