# Buggy code
async def describe_database_restore(
    self,
    tx_snapshot_id: str,
    dump_server_ver_str: Optional[str],
    schema_ddl: bytes,
    schema_ids: List[Tuple[str, str, bytes]],
    blocks: List[Tuple[bytes, bytes]],  # type_id, typespec
) -> RestoreDescriptor:
    schema_object_ids = {
        (s_name.name_from_string(name), qltype if qltype else None): uuidgen.from_bytes(
            objid
        )
        for name, qltype, objid in schema_ids
    }

    if dump_server_ver_str is not None:
        dump_server_ver = verutils.parse_version(dump_server_ver_str)
    else:
        dump_server_ver = None

    schema = await self._introspect_schema_in_snapshot(tx_snapshot_id)
    ctx = await self._ctx_new_con_state(
        dbver=b"",
        io_format=enums.IoFormat.BINARY,
        expect_one=False,
        modaliases=DEFAULT_MODULE_ALIASES_MAP,
        session_config=EMPTY_MAP,
        stmt_mode=enums.CompileStatementMode.ALL,
        json_parameters=False,
        schema=schema,
        schema_object_ids=schema_object_ids,
        compat_ver=dump_server_ver,
    )
    ctx.state.start_tx()

    ddl_source = edgeql.Source.from_string(schema_ddl.decode("utf-8"))
    units = self._compile(ctx=ctx, source=ddl_source)
    schema = ctx.state.current_tx().get_schema()

    restore_blocks = []
    tables = []
    for schema_object_id, typedesc in blocks:
        schema_object_id = uuidgen.from_bytes(schema_object_id)
        obj = schema.get_by_id(schema_object_id)
        desc = sertypes.TypeSerializer.parse(typedesc)

        if isinstance(obj, s_props.Property):
            assert isinstance(desc, sertypes.NamedTupleDesc)
            desc_ptrs = list(desc.fields.keys())
            if set(desc_ptrs) != {"source", "target", "ptr_item_id"}:
                raise RuntimeError("Property table dump data has extra fields")
            cols = {
                "source": "source",
                "target": "target",
                "ptr_item_id": "ptr_item_id",
            }

        elif isinstance(obj, s_links.Link):
            assert isinstance(desc, sertypes.NamedTupleDesc)
            desc_ptrs = list(desc.fields.keys())
            cols = {
                "source": "source",
                "target": "target",
                "ptr_item_id": "ptr_item_id",
            }

            for ptr in obj.get_pointers(schema).objects(schema):
                if ptr.is_endpoint_pointer(schema):
                    continue
                stor_info = pg_types.get_pointer_storage_info(
                    ptr,
                    schema=schema,
                    source=obj,
                    link_bias=True,
                )

                ptr_name = ptr.get_shortname(schema).name
                cols[ptr_name] = stor_info.column_name

            if set(desc_ptrs) != set(cols):
                raise RuntimeError("Link table dump data has extra fields")

        elif isinstance(obj, s_objtypes.ObjectType):
            assert isinstance(desc, sertypes.ShapeDesc)
            desc_ptrs = list(desc.fields.keys())

            cols = {}
            for ptr in obj.get_pointers(schema).objects(schema):
                if ptr.is_endpoint_pointer(schema):
                    continue

                stor_info = pg_types.get_pointer_storage_info(
                    ptr,
                    schema=schema,
                    source=obj,
                )

                if stor_info.table_type == "ObjectType":
                    ptr_name = ptr.get_shortname(schema).name
                    cols[ptr_name] = stor_info.column_name

            if set(desc_ptrs) != set(cols):
                raise RuntimeError("Object table dump data has extra fields")

        else:
            raise AssertionError(
                f"unexpected object type in restore type descriptor: {obj!r}"
            )

        table_name = pg_common.get_backend_name(schema, obj, catenate=True)

        col_list = (pg_common.quote_ident(cols[pn]) for pn in desc_ptrs)

        stmt = (
            f"COPY {table_name} ({', '.join(col_list)})FROM STDIN WITH BINARY"
        ).encode()

        restore_blocks.append(
            RestoreBlockDescriptor(
                schema_object_id=schema_object_id,
                sql_copy_stmt=stmt,
            )
        )

        tables.append(table_name)

    return RestoreDescriptor(
        units=units,
        blocks=restore_blocks,
        tables=tables,
    )


# Traceback (BackendError)
edgedb error: WARNING: unsolicited message ErrorResponse(ErrorResponse { severity: Error, code: 16777216, message: "unhandled errors in a TaskGroup; 1 sub errors: (BackendError)\n + BackendError: relation \"edgedbpub.b33c7457-3ee5-11eb-ada4-4716c5d2f104\" does not exist\n |   File \"edb/server/pgcon/pgcon.pyx\", line 867, in dump\n |     await self._dump(block, output_queue, fragment_suggested_size)\n |   File \"edb/server/pgcon/pgcon.pyx\", line 855, in _dump\n |     raise pgerror.BackendError(fields=er)\n\n", attributes: {1: b"This is most likely a bug in EdgeDB. Please consider opening an issue ticket at https://github.com/edgedb/edgedb/issues/new?template=bug_report.md", 257: b"Traceback (most recent call last):\n  File \"edb/server/mng_port/edgecon.pyx\", line 1635, in edb.server.mng_port.edgecon.EdgeConnection.main\n    await self.dump()\n  File \"edb/server/mng_port/edgecon.pyx\", line 2090, in dump\n    async with taskgroup.TaskGroup() as g:\n  File \"/work/edb/common/taskgroup.py\", line 169, in __aexit__\n    raise me from None\nedb.common.taskgroup.TaskGroupError: unhandled errors in a TaskGroup; 1 sub errors: (BackendError)\n + BackendError: relation \"edgedbpub.b33c7457-3ee5-11eb-ada4-4716c5d2f104\" does not exist\n |   File \"edb/server/pgcon/pgcon.pyx\", line 867, in dump\n |     await self._dump(block, output_queue, fragment_suggested_size)\n |   File \"edb/server/pgcon/pgcon.pyx\", line 855, in _dump\n |     raise pgerror.BackendError(fields=er)\n\n\n"} })

# Fixed code
async def describe_database_restore(
    self,
    tx_snapshot_id: str,
    dump_server_ver_str: Optional[str],
    schema_ddl: bytes,
    schema_ids: List[Tuple[str, str, bytes]],
    blocks: List[Tuple[bytes, bytes]],  # type_id, typespec
) -> RestoreDescriptor:
    schema_object_ids = {
        (s_name.name_from_string(name), qltype if qltype else None): uuidgen.from_bytes(
            objid
        )
        for name, qltype, objid in schema_ids
    }

    if dump_server_ver_str is not None:
        dump_server_ver = verutils.parse_version(dump_server_ver_str)
    else:
        dump_server_ver = None

    schema = await self._introspect_schema_in_snapshot(tx_snapshot_id)
    ctx = await self._ctx_new_con_state(
        dbver=b"",
        io_format=enums.IoFormat.BINARY,
        expect_one=False,
        modaliases=DEFAULT_MODULE_ALIASES_MAP,
        session_config=EMPTY_MAP,
        stmt_mode=enums.CompileStatementMode.ALL,
        json_parameters=False,
        schema=schema,
        schema_object_ids=schema_object_ids,
        compat_ver=dump_server_ver,
    )
    ctx.state.start_tx()

    ddl_source = edgeql.Source.from_string(schema_ddl.decode("utf-8"))
    units = self._compile(ctx=ctx, source=ddl_source)
    schema = ctx.state.current_tx().get_schema()

    restore_blocks = []
    tables = []
    for schema_object_id, typedesc in blocks:
        schema_object_id = uuidgen.from_bytes(schema_object_id)
        obj = schema.get_by_id(schema_object_id)
        desc = sertypes.TypeSerializer.parse(typedesc)

        if isinstance(obj, s_props.Property):
            assert isinstance(desc, sertypes.NamedTupleDesc)
            desc_ptrs = list(desc.fields.keys())
            if set(desc_ptrs) != {"source", "target", "ptr_item_id"}:
                raise RuntimeError("Property table dump data has extra fields")
            cols = {
                "source": "source",
                "target": "target",
                "ptr_item_id": "ptr_item_id",
            }

        elif isinstance(obj, s_links.Link):
            assert isinstance(desc, sertypes.NamedTupleDesc)
            desc_ptrs = list(desc.fields.keys())
            cols = {
                "source": "source",
                "target": "target",
                "ptr_item_id": "ptr_item_id",
            }

            for ptr in obj.get_pointers(schema).objects(schema):
                if not ptr.is_dumpable(schema):
                    continue
                stor_info = pg_types.get_pointer_storage_info(
                    ptr,
                    schema=schema,
                    source=obj,
                    link_bias=True,
                )

                ptr_name = ptr.get_shortname(schema).name
                cols[ptr_name] = stor_info.column_name

            if set(desc_ptrs) != set(cols):
                raise RuntimeError("Link table dump data has extra fields")

        elif isinstance(obj, s_objtypes.ObjectType):
            assert isinstance(desc, sertypes.ShapeDesc)
            desc_ptrs = list(desc.fields.keys())

            cols = {}
            for ptr in obj.get_pointers(schema).objects(schema):
                if not ptr.is_dumpable(schema):
                    continue

                stor_info = pg_types.get_pointer_storage_info(
                    ptr,
                    schema=schema,
                    source=obj,
                )

                if stor_info.table_type == "ObjectType":
                    ptr_name = ptr.get_shortname(schema).name
                    cols[ptr_name] = stor_info.column_name

            if set(desc_ptrs) != set(cols):
                raise RuntimeError("Object table dump data has extra fields")

        else:
            raise AssertionError(
                f"unexpected object type in restore type descriptor: {obj!r}"
            )

        table_name = pg_common.get_backend_name(schema, obj, catenate=True)

        col_list = (pg_common.quote_ident(cols[pn]) for pn in desc_ptrs)

        stmt = (
            f"COPY {table_name} ({', '.join(col_list)})FROM STDIN WITH BINARY"
        ).encode()

        restore_blocks.append(
            RestoreBlockDescriptor(
                schema_object_id=schema_object_id,
                sql_copy_stmt=stmt,
            )
        )

        tables.append(table_name)

    return RestoreDescriptor(
        units=units,
        blocks=restore_blocks,
        tables=tables,
    )