backend/query/information_schema_catalog.h

//
// 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.
//

#ifndef THIRD_PARTY_CLOUD_SPANNER_EMULATOR_BACKEND_QUERY_INFORMATION_SCHEMA_CATALOG_H_
#define THIRD_PARTY_CLOUD_SPANNER_EMULATOR_BACKEND_QUERY_INFORMATION_SCHEMA_CATALOG_H_

#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "google/spanner/admin/database/v1/common.pb.h"
#include "zetasql/public/simple_catalog.h"
#include "zetasql/public/value.h"
#include "absl/container/flat_hash_map.h"
#include "absl/strings/string_view.h"
#include "backend/query/spanner_sys_catalog.h"
#include "backend/schema/catalog/model.h"
#include "backend/schema/catalog/schema.h"
#include "third_party/spanner_pg/ddl/spangres_schema_printer.h"

namespace google {
namespace spanner {
namespace emulator {
namespace backend {

struct ColumnsMetaEntry;
struct IndexColumnsMetaEntry;

// InformationSchemaCatalog provides the INFORMATION_SCHEMA tables.
//
// ZetaSQL reference implementation accesses table data via the catalog objects
// themselves. Hence, this class provides both the catalog and the data
// backing the information schema tables.
//
// Cloud Spanner's information schema is documented at:
//   https://cloud.google.com/spanner/docs/information-schema
//
// The emulator only exposes the default (user) schema and INFORMATION_SCHEMA.
// In production, SPANNER_SYS schemas are also exposed which are not available
// in the emulator.
//
// This class is tested via tests/conformance/cases/information_schema.cc
class InformationSchemaCatalog : public zetasql::SimpleCatalog {
 public:
  static constexpr char kName[] = "INFORMATION_SCHEMA";
  static constexpr char kPGName[] = "PG_INFORMATION_SCHEMA";

  explicit InformationSchemaCatalog(
      const std::string& catalog_name, const Schema* default_schema,
      const SpannerSysCatalog* spanner_sys_catalog);

 private:
  const Schema* default_schema_;
  const SpannerSysCatalog* spanner_sys_catalog_;
  const ::google::spanner::admin::database::v1::DatabaseDialect dialect_;
  absl::flat_hash_map<std::string, std::unique_ptr<zetasql::SimpleTable>>
      tables_by_name_;
  std::unique_ptr<postgres_translator::spangres::SpangresSchemaPrinter>
      pg_schema_printer_;

  inline std::string GetNameForDialect(absl::string_view name);
  std::pair<zetasql::Value, zetasql::Value> GetPGDataTypeAndSpannerType(
      const zetasql::Type* type, std::optional<int64_t> length);

  zetasql::Value GetSpannerType(const Column* column);
  zetasql::Value GetSpannerType(const zetasql::Type* type,
                                  std::optional<int64_t> length);
  zetasql::Value PGDataType(const zetasql::Type* type);
  inline zetasql::Value DialectDefaultSchema();
  inline zetasql::Value DialectBoolValue(bool value);
  zetasql::Value DialectColumnOrdering(const KeyColumn* column);
  inline zetasql::Value DialectTableCatalog();
  inline std::pair<std::string, std::string>
  GetSchemaAndNameForInformationSchema(std::string table_name);

  void FillSchemataTable();
  void FillSpannerStatisticsTable();
  void FillDatabaseOptionsTable();
  void FillColumnOptionsTable();

  void FillTablesTable();
  void FillColumnsTable();
  void FillColumnColumnUsageTable();
  void FillIndexesTable();
  void FillIndexColumnsTable();
  void FillTableConstraintsTable();
  void FillCheckConstraintsTable();
  void FillConstraintTableUsageTable();
  void FillReferentialConstraintsTable();
  void FillKeyColumnUsageTable();
  void FillConstraintColumnUsageTable();
  void FillViewsTable();

  void FillChangeStreamsTable();
  void FillChangeStreamTablesTable();
  void FillChangeStreamOptionsTable();
  void FillChangeStreamColumnsTable();

  void FillSequencesTable();
  void FillSequenceOptionsTable();

  void FillModelsTable();
  void FillModelOptionsTable();
  void FillModelColumnsTable();
  void FillModelColumnOptionsTable();

  void FillModelColumnsTable(const Model& model,
                             const Model::ModelColumn& column,
                             absl::string_view column_kind,
                             int64_t ordinal_position,
                             std::vector<std::vector<zetasql::Value>>* rows);
  void FillModelColumnOptionsTable(
      const Model& model, const Model::ModelColumn& column,
      absl::string_view column_kind,
      std::vector<std::vector<zetasql::Value>>* rows);
  zetasql::Value ParseLocalityGroupOptions(ddl::SetOption option);
  void FillLocalityGroupOptionsTable();

  void FillPropertyGraphsTable();
};

}  // namespace backend
}  // namespace emulator
}  // namespace spanner
}  // namespace google

#endif  // THIRD_PARTY_CLOUD_SPANNER_EMULATOR_BACKEND_QUERY_INFORMATION_SCHEMA_CATALOG_H_