backend/schema/catalog/property_graph.proto

//
// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

syntax = "proto2";

package google.spanner.emulator.backend.catalog;

// TODO: remove this proto and use the ZetaSQL one once when it's released.
// Top-level protobuf to describe a property graph.
message PropertyGraphProto {
  // Name of the catalog containing the property graph.
  optional string catalog = 1;
  // Name of the schema containing the property graph.
  optional string schema = 2;
  // Name of the property graph.
  optional string name = 3;

  repeated GraphElementTableProto node_tables = 4;
  repeated GraphElementTableProto edge_tables = 5;
  repeated GraphElementLabelProto labels = 6;
  repeated GraphPropertyDeclarationProto property_declarations = 7;
}

// To describe a node or edge within a property graph.
message GraphElementTableProto {
  enum Kind {
    KIND_UNSPECIFIED = 0;
    NODE = 1;
    EDGE = 2;
  }
  // Name of the graph element table.
  optional string name = 1;
  optional Kind kind = 2;

  // Name of the catalog containing the base table.
  optional string base_catalog_name = 3;
  // Name of the schema containing the base table.
  optional string base_schema_name = 4;
  // Name of the table that this element table is based on.
  optional string base_table_name = 5;

  // Names of the columns that are part of the element key. At least one.
  repeated string key_columns = 6;
  // Cross-references to the `name` field in `GraphElementLabelProto`.
  repeated string label_names = 7;
  repeated GraphPropertyDefinitionProto property_definitions = 8;

  // The SQL expression that defines the dynamic label.
  optional string dynamic_label_expr = 11;
  // The SQL expression that defines the dynamic property.
  optional string dynamic_property_expr = 12;

  // source_node_table and destination_node_table are only set when `kind` is
  // EDGE.
  optional GraphNodeTableReferenceProto source_node_table = 9;
  optional GraphNodeTableReferenceProto destination_node_table = 10;
}

// To describe a source or destination node of an edge.
message GraphNodeTableReferenceProto {
  // Cross-references to the `name` field in `GraphElementTableProto`.
  optional string node_table_name = 1;
  // Names of the columns that are part of the source or destination key. At
  // least one.
  repeated string edge_table_columns = 2;
  repeated string node_table_columns = 3;
}

// To describe a label.
message GraphElementLabelProto {
  // Name of the label.
  optional string name = 1;
  // Cross-references to the `name` field in `GraphPropertyDeclarationProto`.
  repeated string property_declaration_names = 2;
}

// To describe a property declaration.
message GraphPropertyDeclarationProto {
  // Name of the property.
  optional string name = 1;
  // Type of the property.
  optional string type = 2;
}

// To describe a property definition.
message GraphPropertyDefinitionProto {
  // Cross-references to the `name` field in `GraphPropertyDeclarationProto`.
  optional string property_declaration_name = 1;
  // The SQL expression that defines the property.
  optional string value_expression_sql = 2;
}