Add vertex and edge composite types with direct field access optimization

[MuhammadTahaNaveed]

• 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
• 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
• Add regression tests

[Copilot]

Pull request overview

This PR introduces significant performance optimizations by adding composite types (vertex and edge) alongside the existing agtype representation. The changes enable direct field access without rebuilding agtype objects for read-only queries.

Changes:

• Introduces composite types vertex(id, label, properties) and edge(id, label, start_id, end_id, properties) with implicit casts to agtype
• Optimizes accessor functions (id, properties, label, type, start_id, end_id) to use FieldSelect for direct field extraction from composite types
• Updates _agtype_build_vertex/edge to accept agtype labels instead of cstring, and modifies executors to convert labels accordingly
• Adds comprehensive regression tests for accessor optimizations and composite type returns

Reviewed changes

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/include/utils/agtype.h	Adds Oid accessors for VERTEXOID and EDGEOID composite types
src/include/parser/cypher_expr.h	Declares helper functions for entity detection and field extraction
src/include/parser/cypher_clause.h	Adds declarations for record field info helpers
src/include/catalog/ag_label.h	Adds get_label_name function declaration
src/backend/utils/adt/agtype.c	Implements vertex/edge composite type support, conversion functions, and updates build functions to accept agtype labels
src/backend/parser/cypher_expr.c	Implements accessor function optimization and entity coercion logic
src/backend/parser/cypher_clause.c	Updates entity creation to use RowExpr with composite types and adds entity coercion for write clauses
src/backend/executor/cypher_set.c	Updates to use string_to_agtype for label parameters
src/backend/executor/cypher_merge.c	Updates to use string_to_agtype for label parameters
src/backend/executor/cypher_create.c	Updates to use string_to_agtype for label parameters
src/backend/catalog/ag_label.c	Changes _label_name to return agtype and adds cached label lookup
sql/agtype_graphid.sql	Defines composite types, cast functions, and updates function signatures
sql/age_scalar.sql	Adds _get_vertex_by_graphid helper function
sql/age_main.sql	Removes old _label_name function definition
regress/sql/expr.sql	Adds comprehensive tests for accessor optimizations and composite types
regress/sql/cypher_with.sql	Adds tests for accessor optimizations in WITH clauses
regress/sql/agtype.sql	Updates tests to use agtype labels instead of cstring
regress/expected/*.out	Updated expected test outputs

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[Copilot]

The comment contains a typo: "stictly" should be "strictly".

Suggested change

	* our executors are stictly tied to agtype.
	* our executors are strictly tied to agtype.