google-cloud 0.2.1

// Copyright 2019 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 = "proto3";

package google.spanner.v1;

import "google/api/annotations.proto";
import "google/protobuf/empty.proto";
import "google/protobuf/struct.proto";
import "google/protobuf/timestamp.proto";
import "google/rpc/status.proto";
import "google/spanner/v1/keys.proto";
import "google/spanner/v1/mutation.proto";
import "google/spanner/v1/result_set.proto";
import "google/spanner/v1/transaction.proto";
import "google/spanner/v1/type.proto";

option csharp_namespace = "Google.Cloud.Spanner.V1";
option go_package = "google.golang.org/genproto/googleapis/spanner/v1;spanner";
option java_multiple_files = true;
option java_outer_classname = "SpannerProto";
option java_package = "com.google.spanner.v1";
option php_namespace = "Google\\Cloud\\Spanner\\V1";

// Cloud Spanner API
//
// The Cloud Spanner API can be used to manage sessions and execute
// transactions on data stored in Cloud Spanner databases.
service Spanner {
  // Creates a new session. A session can be used to perform
  // transactions that read and/or modify data in a Cloud Spanner database.
  // Sessions are meant to be reused for many consecutive
  // transactions.
  //
  // Sessions can only execute one transaction at a time. To execute
  // multiple concurrent read-write/write-only transactions, create
  // multiple sessions. Note that standalone reads and queries use a
  // transaction internally, and count toward the one transaction
  // limit.
  //
  // Cloud Spanner limits the number of sessions that can exist at any given
  // time; thus, it is a good idea to delete idle and/or unneeded sessions.
  // Aside from explicit deletes, Cloud Spanner can delete sessions for which no
  // operations are sent for more than an hour. If a session is deleted,
  // requests to it return `NOT_FOUND`.
  //
  // Idle sessions can be kept alive by sending a trivial SQL query
  // periodically, e.g., `"SELECT 1"`.
  rpc CreateSession(CreateSessionRequest) returns (Session) {
    option (google.api.http) = {
      post: "/v1/{database=projects/*/instances/*/databases/*}/sessions"
      body: "*"
    };
  }

  // Creates multiple new sessions.
  //
  // This API can be used to initialize a session cache on the clients.
  // See https://goo.gl/TgSFN2 for best practices on session cache management.
  rpc BatchCreateSessions(BatchCreateSessionsRequest)
      returns (BatchCreateSessionsResponse) {
    option (google.api.http) = {
      post: "/v1/{database=projects/*/instances/*/databases/*}/sessions:batchCreate"
      body: "*"
    };
  }

  // Gets a session. Returns `NOT_FOUND` if the session does not exist.
  // This is mainly useful for determining whether a session is still
  // alive.
  rpc GetSession(GetSessionRequest) returns (Session) {
    option (google.api.http) = {
      get: "/v1/{name=projects/*/instances/*/databases/*/sessions/*}"
    };
  }

  // Lists all sessions in a given database.
  rpc ListSessions(ListSessionsRequest) returns (ListSessionsResponse) {
    option (google.api.http) = {
      get: "/v1/{database=projects/*/instances/*/databases/*}/sessions"
    };
  }

  // Ends a session, releasing server resources associated with it. This will
  // asynchronously trigger cancellation of any operations that are running with
  // this session.
  rpc DeleteSession(DeleteSessionRequest) returns (google.protobuf.Empty) {
    option (google.api.http) = {
      delete: "/v1/{name=projects/*/instances/*/databases/*/sessions/*}"
    };
  }

  // Executes an SQL statement, returning all results in a single reply. This
  // method cannot be used to return a result set larger than 10 MiB;
  // if the query yields more data than that, the query fails with
  // a `FAILED_PRECONDITION` error.
  //
  // Operations inside read-write transactions might return `ABORTED`. If
  // this occurs, the application should restart the transaction from
  // the beginning. See [Transaction][google.spanner.v1.Transaction] for more
  // details.
  //
  // Larger result sets can be fetched in streaming fashion by calling
  // [ExecuteStreamingSql][google.spanner.v1.Spanner.ExecuteStreamingSql]
  // instead.
  rpc ExecuteSql(ExecuteSqlRequest) returns (ResultSet) {
    option (google.api.http) = {
      post: "/v1/{session=projects/*/instances/*/databases/*/sessions/*}:executeSql"
      body: "*"
    };
  }

  // Like [ExecuteSql][google.spanner.v1.Spanner.ExecuteSql], except returns the
  // result set as a stream. Unlike
  // [ExecuteSql][google.spanner.v1.Spanner.ExecuteSql], there is no limit on
  // the size of the returned result set. However, no individual row in the
  // result set can exceed 100 MiB, and no column value can exceed 10 MiB.
  rpc ExecuteStreamingSql(ExecuteSqlRequest) returns (stream PartialResultSet) {
    option (google.api.http) = {
      post: "/v1/{session=projects/*/instances/*/databases/*/sessions/*}:executeStreamingSql"
      body: "*"
    };
  }

  // Executes a batch of SQL DML statements. This method allows many statements
  // to be run with lower latency than submitting them sequentially with
  // [ExecuteSql][google.spanner.v1.Spanner.ExecuteSql].
  //
  // Statements are executed in order, sequentially.
  // [ExecuteBatchDmlResponse][Spanner.ExecuteBatchDmlResponse] will contain a
  // [ResultSet][google.spanner.v1.ResultSet] for each DML statement that has
  // successfully executed. If a statement fails, its error status will be
  // returned as part of the
  // [ExecuteBatchDmlResponse][Spanner.ExecuteBatchDmlResponse]. Execution will
  // stop at the first failed statement; the remaining statements will not run.
  //
  // ExecuteBatchDml is expected to return an OK status with a response even if
  // there was an error while processing one of the DML statements. Clients must
  // inspect response.status to determine if there were any errors while
  // processing the request.
  //
  // See more details in
  // [ExecuteBatchDmlRequest][Spanner.ExecuteBatchDmlRequest] and
  // [ExecuteBatchDmlResponse][Spanner.ExecuteBatchDmlResponse].
  rpc ExecuteBatchDml(ExecuteBatchDmlRequest)
      returns (ExecuteBatchDmlResponse) {
    option (google.api.http) = {
      post: "/v1/{session=projects/*/instances/*/databases/*/sessions/*}:executeBatchDml"
      body: "*"
    };
  }

  // Reads rows from the database using key lookups and scans, as a
  // simple key/value style alternative to
  // [ExecuteSql][google.spanner.v1.Spanner.ExecuteSql].  This method cannot be
  // used to return a result set larger than 10 MiB; if the read matches more
  // data than that, the read fails with a `FAILED_PRECONDITION`
  // error.
  //
  // Reads inside read-write transactions might return `ABORTED`. If
  // this occurs, the application should restart the transaction from
  // the beginning. See [Transaction][google.spanner.v1.Transaction] for more
  // details.
  //
  // Larger result sets can be yielded in streaming fashion by calling
  // [StreamingRead][google.spanner.v1.Spanner.StreamingRead] instead.
  rpc Read(ReadRequest) returns (ResultSet) {
    option (google.api.http) = {
      post: "/v1/{session=projects/*/instances/*/databases/*/sessions/*}:read"
      body: "*"
    };
  }

  // Like [Read][google.spanner.v1.Spanner.Read], except returns the result set
  // as a stream. Unlike [Read][google.spanner.v1.Spanner.Read], there is no
  // limit on the size of the returned result set. However, no individual row in
  // the result set can exceed 100 MiB, and no column value can exceed
  // 10 MiB.
  rpc StreamingRead(ReadRequest) returns (stream PartialResultSet) {
    option (google.api.http) = {
      post: "/v1/{session=projects/*/instances/*/databases/*/sessions/*}:streamingRead"
      body: "*"
    };
  }

  // Begins a new transaction. This step can often be skipped:
  // [Read][google.spanner.v1.Spanner.Read],
  // [ExecuteSql][google.spanner.v1.Spanner.ExecuteSql] and
  // [Commit][google.spanner.v1.Spanner.Commit] can begin a new transaction as a
  // side-effect.
  rpc BeginTransaction(BeginTransactionRequest) returns (Transaction) {
    option (google.api.http) = {
      post: "/v1/{session=projects/*/instances/*/databases/*/sessions/*}:beginTransaction"
      body: "*"
    };
  }

  // Commits a transaction. The request includes the mutations to be
  // applied to rows in the database.
  //
  // `Commit` might return an `ABORTED` error. This can occur at any time;
  // commonly, the cause is conflicts with concurrent
  // transactions. However, it can also happen for a variety of other
  // reasons. If `Commit` returns `ABORTED`, the caller should re-attempt
  // the transaction from the beginning, re-using the same session.
  rpc Commit(CommitRequest) returns (CommitResponse) {
    option (google.api.http) = {
      post: "/v1/{session=projects/*/instances/*/databases/*/sessions/*}:commit"
      body: "*"
    };
  }

  // Rolls back a transaction, releasing any locks it holds. It is a good
  // idea to call this for any transaction that includes one or more
  // [Read][google.spanner.v1.Spanner.Read] or
  // [ExecuteSql][google.spanner.v1.Spanner.ExecuteSql] requests and ultimately
  // decides not to commit.
  //
  // `Rollback` returns `OK` if it successfully aborts the transaction, the
  // transaction was already aborted, or the transaction is not
  // found. `Rollback` never returns `ABORTED`.
  rpc Rollback(RollbackRequest) returns (google.protobuf.Empty) {
    option (google.api.http) = {
      post: "/v1/{session=projects/*/instances/*/databases/*/sessions/*}:rollback"
      body: "*"
    };
  }

  // Creates a set of partition tokens that can be used to execute a query
  // operation in parallel.  Each of the returned partition tokens can be used
  // by [ExecuteStreamingSql][google.spanner.v1.Spanner.ExecuteStreamingSql] to
  // specify a subset of the query result to read.  The same session and
  // read-only transaction must be used by the PartitionQueryRequest used to
  // create the partition tokens and the ExecuteSqlRequests that use the
  // partition tokens.
  //
  // Partition tokens become invalid when the session used to create them
  // is deleted, is idle for too long, begins a new transaction, or becomes too
  // old.  When any of these happen, it is not possible to resume the query, and
  // the whole operation must be restarted from the beginning.
  rpc PartitionQuery(PartitionQueryRequest) returns (PartitionResponse) {
    option (google.api.http) = {
      post: "/v1/{session=projects/*/instances/*/databases/*/sessions/*}:partitionQuery"
      body: "*"
    };
  }

  // Creates a set of partition tokens that can be used to execute a read
  // operation in parallel.  Each of the returned partition tokens can be used
  // by [StreamingRead][google.spanner.v1.Spanner.StreamingRead] to specify a
  // subset of the read result to read.  The same session and read-only
  // transaction must be used by the PartitionReadRequest used to create the
  // partition tokens and the ReadRequests that use the partition tokens.  There
  // are no ordering guarantees on rows returned among the returned partition
  // tokens, or even within each individual StreamingRead call issued with a
  // partition_token.
  //
  // Partition tokens become invalid when the session used to create them
  // is deleted, is idle for too long, begins a new transaction, or becomes too
  // old.  When any of these happen, it is not possible to resume the read, and
  // the whole operation must be restarted from the beginning.
  rpc PartitionRead(PartitionReadRequest) returns (PartitionResponse) {
    option (google.api.http) = {
      post: "/v1/{session=projects/*/instances/*/databases/*/sessions/*}:partitionRead"
      body: "*"
    };
  }
}

// The request for [CreateSession][google.spanner.v1.Spanner.CreateSession].
message CreateSessionRequest {
  // Required. The database in which the new session is created.
  string database = 1;

  // The session to create.
  Session session = 2;
}

// The request for
// [BatchCreateSessions][google.spanner.v1.Spanner.BatchCreateSessions].
message BatchCreateSessionsRequest {
  // Required. The database in which the new sessions are created.
  string database = 1;

  // Parameters to be applied to each created session.
  Session session_template = 2;

  // Required. The number of sessions to be created in this batch call.
  // The API may return fewer than the requested number of sessions. If a
  // specific number of sessions are desired, the client can make additional
  // calls to BatchCreateSessions (adjusting
  // [session_count][google.spanner.v1.BatchCreateSessionsRequest.session_count]
  // as necessary).
  int32 session_count = 3;
}

// The response for
// [BatchCreateSessions][google.spanner.v1.Spanner.BatchCreateSessions].
message BatchCreateSessionsResponse {
  // The freshly created sessions.
  repeated Session session = 1;
}

// A session in the Cloud Spanner API.
message Session {
  // The name of the session. This is always system-assigned; values provided
  // when creating a session are ignored.
  string name = 1;

  // The labels for the session.
  //
  //  * Label keys must be between 1 and 63 characters long and must conform to
  //    the following regular expression: `[a-z]([-a-z0-9]*[a-z0-9])?`.
  //  * Label values must be between 0 and 63 characters long and must conform
  //    to the regular expression `([a-z]([-a-z0-9]*[a-z0-9])?)?`.
  //  * No more than 64 labels can be associated with a given session.
  //
  // See https://goo.gl/xmQnxf for more information on and examples of labels.
  map<string, string> labels = 2;

  // Output only. The timestamp when the session is created.
  google.protobuf.Timestamp create_time = 3;

  // Output only. The approximate timestamp when the session is last used. It is
  // typically earlier than the actual last use time.
  google.protobuf.Timestamp approximate_last_use_time = 4;
}

// The request for [GetSession][google.spanner.v1.Spanner.GetSession].
message GetSessionRequest {
  // Required. The name of the session to retrieve.
  string name = 1;
}

// The request for [ListSessions][google.spanner.v1.Spanner.ListSessions].
message ListSessionsRequest {
  // Required. The database in which to list sessions.
  string database = 1;

  // Number of sessions to be returned in the response. If 0 or less, defaults
  // to the server's maximum allowed page size.
  int32 page_size = 2;

  // If non-empty, `page_token` should contain a
  // [next_page_token][google.spanner.v1.ListSessionsResponse.next_page_token]
  // from a previous
  // [ListSessionsResponse][google.spanner.v1.ListSessionsResponse].
  string page_token = 3;

  // An expression for filtering the results of the request. Filter rules are
  // case insensitive. The fields eligible for filtering are:
  //
  //   * `labels.key` where key is the name of a label
  //
  // Some examples of using filters are:
  //
  //   * `labels.env:*` --> The session has the label "env".
  //   * `labels.env:dev` --> The session has the label "env" and the value of
  //                        the label contains the string "dev".
  string filter = 4;
}

// The response for [ListSessions][google.spanner.v1.Spanner.ListSessions].
message ListSessionsResponse {
  // The list of requested sessions.
  repeated Session sessions = 1;

  // `next_page_token` can be sent in a subsequent
  // [ListSessions][google.spanner.v1.Spanner.ListSessions] call to fetch more
  // of the matching sessions.
  string next_page_token = 2;
}

// The request for [DeleteSession][google.spanner.v1.Spanner.DeleteSession].
message DeleteSessionRequest {
  // Required. The name of the session to delete.
  string name = 1;
}

// The request for [ExecuteSql][google.spanner.v1.Spanner.ExecuteSql] and
// [ExecuteStreamingSql][google.spanner.v1.Spanner.ExecuteStreamingSql].
message ExecuteSqlRequest {
  // Mode in which the statement must be processed.
  enum QueryMode {
    // The default mode. Only the statement results are returned.
    NORMAL = 0;

    // This mode returns only the query plan, without any results or
    // execution statistics information.
    PLAN = 1;

    // This mode returns both the query plan and the execution statistics along
    // with the results.
    PROFILE = 2;
  }

  // Required. The session in which the SQL query should be performed.
  string session = 1;

  // The transaction to use.
  //
  // For queries, if none is provided, the default is a temporary read-only
  // transaction with strong concurrency.
  //
  // Standard DML statements require a ReadWrite transaction. Single-use
  // transactions are not supported (to avoid replay).  The caller must
  // either supply an existing transaction ID or begin a new transaction.
  //
  // Partitioned DML requires an existing PartitionedDml transaction ID.
  TransactionSelector transaction = 2;

  // Required. The SQL string.
  string sql = 3;

  // The SQL string can contain parameter placeholders. A parameter
  // placeholder consists of `'@'` followed by the parameter
  // name. Parameter names consist of any combination of letters,
  // numbers, and underscores.
  //
  // Parameters can appear anywhere that a literal value is expected.  The same
  // parameter name can be used more than once, for example:
  //   `"WHERE id > @msg_id AND id < @msg_id + 100"`
  //
  // It is an error to execute an SQL statement with unbound parameters.
  //
  // Parameter values are specified using `params`, which is a JSON
  // object whose keys are parameter names, and whose values are the
  // corresponding parameter values.
  google.protobuf.Struct params = 4;

  // It is not always possible for Cloud Spanner to infer the right SQL type
  // from a JSON value.  For example, values of type `BYTES` and values
  // of type `STRING` both appear in
  // [params][google.spanner.v1.ExecuteSqlRequest.params] as JSON strings.
  //
  // In these cases, `param_types` can be used to specify the exact
  // SQL type for some or all of the SQL statement parameters. See the
  // definition of [Type][google.spanner.v1.Type] for more information
  // about SQL types.
  map<string, Type> param_types = 5;

  // If this request is resuming a previously interrupted SQL statement
  // execution, `resume_token` should be copied from the last
  // [PartialResultSet][google.spanner.v1.PartialResultSet] yielded before the
  // interruption. Doing this enables the new SQL statement execution to resume
  // where the last one left off. The rest of the request parameters must
  // exactly match the request that yielded this token.
  bytes resume_token = 6;

  // Used to control the amount of debugging information returned in
  // [ResultSetStats][google.spanner.v1.ResultSetStats]. If
  // [partition_token][google.spanner.v1.ExecuteSqlRequest.partition_token] is
  // set, [query_mode][google.spanner.v1.ExecuteSqlRequest.query_mode] can only
  // be set to
  // [QueryMode.NORMAL][google.spanner.v1.ExecuteSqlRequest.QueryMode.NORMAL].
  QueryMode query_mode = 7;

  // If present, results will be restricted to the specified partition
  // previously created using PartitionQuery().  There must be an exact
  // match for the values of fields common to this message and the
  // PartitionQueryRequest message used to create this partition_token.
  bytes partition_token = 8;

  // A per-transaction sequence number used to identify this request. This
  // makes each request idempotent such that if the request is received multiple
  // times, at most one will succeed.
  //
  // The sequence number must be monotonically increasing within the
  // transaction. If a request arrives for the first time with an out-of-order
  // sequence number, the transaction may be aborted. Replays of previously
  // handled requests will yield the same response as the first execution.
  //
  // Required for DML statements. Ignored for queries.
  int64 seqno = 9;
}

// The request for [ExecuteBatchDml][google.spanner.v1.Spanner.ExecuteBatchDml]
message ExecuteBatchDmlRequest {
  // A single DML statement.
  message Statement {
    // Required. The DML string.
    string sql = 1;

    // The DML string can contain parameter placeholders. A parameter
    // placeholder consists of `'@'` followed by the parameter
    // name. Parameter names consist of any combination of letters,
    // numbers, and underscores.
    //
    // Parameters can appear anywhere that a literal value is expected.  The
    // same parameter name can be used more than once, for example:
    //   `"WHERE id > @msg_id AND id < @msg_id + 100"`
    //
    // It is an error to execute an SQL statement with unbound parameters.
    //
    // Parameter values are specified using `params`, which is a JSON
    // object whose keys are parameter names, and whose values are the
    // corresponding parameter values.
    google.protobuf.Struct params = 2;

    // It is not always possible for Cloud Spanner to infer the right SQL type
    // from a JSON value.  For example, values of type `BYTES` and values
    // of type `STRING` both appear in
    // [params][google.spanner.v1.ExecuteBatchDmlRequest.Statement.params] as
    // JSON strings.
    //
    // In these cases, `param_types` can be used to specify the exact
    // SQL type for some or all of the SQL statement parameters. See the
    // definition of [Type][google.spanner.v1.Type] for more information
    // about SQL types.
    map<string, Type> param_types = 3;
  }

  // Required. The session in which the DML statements should be performed.
  string session = 1;

  // The transaction to use. A ReadWrite transaction is required. Single-use
  // transactions are not supported (to avoid replay).  The caller must either
  // supply an existing transaction ID or begin a new transaction.
  TransactionSelector transaction = 2;

  // The list of statements to execute in this batch. Statements are executed
  // serially, such that the effects of statement i are visible to statement
  // i+1. Each statement must be a DML statement. Execution will stop at the
  // first failed statement; the remaining statements will not run.
  //
  // REQUIRES: statements_size() > 0.
  repeated Statement statements = 3;

  // A per-transaction sequence number used to identify this request. This is
  // used in the same space as the seqno in
  // [ExecuteSqlRequest][Spanner.ExecuteSqlRequest]. See more details
  // in [ExecuteSqlRequest][Spanner.ExecuteSqlRequest].
  int64 seqno = 4;
}

// The response for
// [ExecuteBatchDml][google.spanner.v1.Spanner.ExecuteBatchDml]. Contains a list
// of [ResultSet][google.spanner.v1.ResultSet], one for each DML statement that
// has successfully executed. If a statement fails, the error is returned as
// part of the response payload. Clients can determine whether all DML
// statements have run successfully, or if a statement failed, using one of the
// following approaches:
//
//   1. Check if 'status' field is OkStatus.
//   2. Check if result_sets_size() equals the number of statements in
//      [ExecuteBatchDmlRequest][Spanner.ExecuteBatchDmlRequest].
//
// Example 1: A request with 5 DML statements, all executed successfully.
// Result: A response with 5 ResultSets, one for each statement in the same
// order, and an OK status.
//
// Example 2: A request with 5 DML statements. The 3rd statement has a syntax
// error.
// Result: A response with 2 ResultSets, for the first 2 statements that
// run successfully, and a syntax error (INVALID_ARGUMENT) status. From
// result_set_size() client can determine that the 3rd statement has failed.
message ExecuteBatchDmlResponse {
  // ResultSets, one for each statement in the request that ran successfully, in
  // the same order as the statements in the request. Each
  // [ResultSet][google.spanner.v1.ResultSet] will not contain any rows. The
  // [ResultSetStats][google.spanner.v1.ResultSetStats] in each
  // [ResultSet][google.spanner.v1.ResultSet] will contain the number of rows
  // modified by the statement.
  //
  // Only the first ResultSet in the response contains a valid
  // [ResultSetMetadata][google.spanner.v1.ResultSetMetadata].
  repeated ResultSet result_sets = 1;

  // If all DML statements are executed successfully, status will be OK.
  // Otherwise, the error status of the first failed statement.
  google.rpc.Status status = 2;
}

// Options for a PartitionQueryRequest and
// PartitionReadRequest.
message PartitionOptions {
  // **Note:** This hint is currently ignored by PartitionQuery and
  // PartitionRead requests.
  //
  // The desired data size for each partition generated.  The default for this
  // option is currently 1 GiB.  This is only a hint. The actual size of each
  // partition may be smaller or larger than this size request.
  int64 partition_size_bytes = 1;

  // **Note:** This hint is currently ignored by PartitionQuery and
  // PartitionRead requests.
  //
  // The desired maximum number of partitions to return.  For example, this may
  // be set to the number of workers available.  The default for this option
  // is currently 10,000. The maximum value is currently 200,000.  This is only
  // a hint.  The actual number of partitions returned may be smaller or larger
  // than this maximum count request.
  int64 max_partitions = 2;
}

// The request for [PartitionQuery][google.spanner.v1.Spanner.PartitionQuery]
message PartitionQueryRequest {
  // Required. The session used to create the partitions.
  string session = 1;

  // Read only snapshot transactions are supported, read/write and single use
  // transactions are not.
  TransactionSelector transaction = 2;

  // The query request to generate partitions for. The request will fail if
  // the query is not root partitionable. The query plan of a root
  // partitionable query has a single distributed union operator. A distributed
  // union operator conceptually divides one or more tables into multiple
  // splits, remotely evaluates a subquery independently on each split, and
  // then unions all results.
  //
  // This must not contain DML commands, such as INSERT, UPDATE, or
  // DELETE. Use
  // [ExecuteStreamingSql][google.spanner.v1.Spanner.ExecuteStreamingSql] with a
  // PartitionedDml transaction for large, partition-friendly DML operations.
  string sql = 3;

  // The SQL query string can contain parameter placeholders. A parameter
  // placeholder consists of `'@'` followed by the parameter
  // name. Parameter names consist of any combination of letters,
  // numbers, and underscores.
  //
  // Parameters can appear anywhere that a literal value is expected.  The same
  // parameter name can be used more than once, for example:
  //   `"WHERE id > @msg_id AND id < @msg_id + 100"`
  //
  // It is an error to execute an SQL query with unbound parameters.
  //
  // Parameter values are specified using `params`, which is a JSON
  // object whose keys are parameter names, and whose values are the
  // corresponding parameter values.
  google.protobuf.Struct params = 4;

  // It is not always possible for Cloud Spanner to infer the right SQL type
  // from a JSON value.  For example, values of type `BYTES` and values
  // of type `STRING` both appear in
  // [params][google.spanner.v1.PartitionQueryRequest.params] as JSON strings.
  //
  // In these cases, `param_types` can be used to specify the exact
  // SQL type for some or all of the SQL query parameters. See the
  // definition of [Type][google.spanner.v1.Type] for more information
  // about SQL types.
  map<string, Type> param_types = 5;

  // Additional options that affect how many partitions are created.
  PartitionOptions partition_options = 6;
}

// The request for [PartitionRead][google.spanner.v1.Spanner.PartitionRead]
message PartitionReadRequest {
  // Required. The session used to create the partitions.
  string session = 1;

  // Read only snapshot transactions are supported, read/write and single use
  // transactions are not.
  TransactionSelector transaction = 2;

  // Required. The name of the table in the database to be read.
  string table = 3;

  // If non-empty, the name of an index on
  // [table][google.spanner.v1.PartitionReadRequest.table]. This index is used
  // instead of the table primary key when interpreting
  // [key_set][google.spanner.v1.PartitionReadRequest.key_set] and sorting
  // result rows. See [key_set][google.spanner.v1.PartitionReadRequest.key_set]
  // for further information.
  string index = 4;

  // The columns of [table][google.spanner.v1.PartitionReadRequest.table] to be
  // returned for each row matching this request.
  repeated string columns = 5;

  // Required. `key_set` identifies the rows to be yielded. `key_set` names the
  // primary keys of the rows in
  // [table][google.spanner.v1.PartitionReadRequest.table] to be yielded, unless
  // [index][google.spanner.v1.PartitionReadRequest.index] is present. If
  // [index][google.spanner.v1.PartitionReadRequest.index] is present, then
  // [key_set][google.spanner.v1.PartitionReadRequest.key_set] instead names
  // index keys in [index][google.spanner.v1.PartitionReadRequest.index].
  //
  // It is not an error for the `key_set` to name rows that do not
  // exist in the database. Read yields nothing for nonexistent rows.
  KeySet key_set = 6;

  // Additional options that affect how many partitions are created.
  PartitionOptions partition_options = 9;
}

// Information returned for each partition returned in a
// PartitionResponse.
message Partition {
  // This token can be passed to Read, StreamingRead, ExecuteSql, or
  // ExecuteStreamingSql requests to restrict the results to those identified by
  // this partition token.
  bytes partition_token = 1;
}

// The response for [PartitionQuery][google.spanner.v1.Spanner.PartitionQuery]
// or [PartitionRead][google.spanner.v1.Spanner.PartitionRead]
message PartitionResponse {
  // Partitions created by this request.
  repeated Partition partitions = 1;

  // Transaction created by this request.
  Transaction transaction = 2;
}

// The request for [Read][google.spanner.v1.Spanner.Read] and
// [StreamingRead][google.spanner.v1.Spanner.StreamingRead].
message ReadRequest {
  // Required. The session in which the read should be performed.
  string session = 1;

  // The transaction to use. If none is provided, the default is a
  // temporary read-only transaction with strong concurrency.
  TransactionSelector transaction = 2;

  // Required. The name of the table in the database to be read.
  string table = 3;

  // If non-empty, the name of an index on
  // [table][google.spanner.v1.ReadRequest.table]. This index is used instead of
  // the table primary key when interpreting
  // [key_set][google.spanner.v1.ReadRequest.key_set] and sorting result rows.
  // See [key_set][google.spanner.v1.ReadRequest.key_set] for further
  // information.
  string index = 4;

  // The columns of [table][google.spanner.v1.ReadRequest.table] to be returned
  // for each row matching this request.
  repeated string columns = 5;

  // Required. `key_set` identifies the rows to be yielded. `key_set` names the
  // primary keys of the rows in [table][google.spanner.v1.ReadRequest.table] to
  // be yielded, unless [index][google.spanner.v1.ReadRequest.index] is present.
  // If [index][google.spanner.v1.ReadRequest.index] is present, then
  // [key_set][google.spanner.v1.ReadRequest.key_set] instead names index keys
  // in [index][google.spanner.v1.ReadRequest.index].
  //
  // If the [partition_token][google.spanner.v1.ReadRequest.partition_token]
  // field is empty, rows are yielded in table primary key order (if
  // [index][google.spanner.v1.ReadRequest.index] is empty) or index key order
  // (if [index][google.spanner.v1.ReadRequest.index] is non-empty).  If the
  // [partition_token][google.spanner.v1.ReadRequest.partition_token] field is
  // not empty, rows will be yielded in an unspecified order.
  //
  // It is not an error for the `key_set` to name rows that do not
  // exist in the database. Read yields nothing for nonexistent rows.
  KeySet key_set = 6;

  // If greater than zero, only the first `limit` rows are yielded. If `limit`
  // is zero, the default is no limit. A limit cannot be specified if
  // `partition_token` is set.
  int64 limit = 8;

  // If this request is resuming a previously interrupted read,
  // `resume_token` should be copied from the last
  // [PartialResultSet][google.spanner.v1.PartialResultSet] yielded before the
  // interruption. Doing this enables the new read to resume where the last read
  // left off. The rest of the request parameters must exactly match the request
  // that yielded this token.
  bytes resume_token = 9;

  // If present, results will be restricted to the specified partition
  // previously created using PartitionRead().    There must be an exact
  // match for the values of fields common to this message and the
  // PartitionReadRequest message used to create this partition_token.
  bytes partition_token = 10;
}

// The request for
// [BeginTransaction][google.spanner.v1.Spanner.BeginTransaction].
message BeginTransactionRequest {
  // Required. The session in which the transaction runs.
  string session = 1;

  // Required. Options for the new transaction.
  TransactionOptions options = 2;
}

// The request for [Commit][google.spanner.v1.Spanner.Commit].
message CommitRequest {
  // Required. The session in which the transaction to be committed is running.
  string session = 1;

  // Required. The transaction in which to commit.
  oneof transaction {
    // Commit a previously-started transaction.
    bytes transaction_id = 2;

    // Execute mutations in a temporary transaction. Note that unlike
    // commit of a previously-started transaction, commit with a
    // temporary transaction is non-idempotent. That is, if the
    // `CommitRequest` is sent to Cloud Spanner more than once (for
    // instance, due to retries in the application, or in the
    // transport library), it is possible that the mutations are
    // executed more than once. If this is undesirable, use
    // [BeginTransaction][google.spanner.v1.Spanner.BeginTransaction] and
    // [Commit][google.spanner.v1.Spanner.Commit] instead.
    TransactionOptions single_use_transaction = 3;
  }

  // The mutations to be executed when this transaction commits. All
  // mutations are applied atomically, in the order they appear in
  // this list.
  repeated Mutation mutations = 4;
}

// The response for [Commit][google.spanner.v1.Spanner.Commit].
message CommitResponse {
  // The Cloud Spanner timestamp at which the transaction committed.
  google.protobuf.Timestamp commit_timestamp = 1;
}

// The request for [Rollback][google.spanner.v1.Spanner.Rollback].
message RollbackRequest {
  // Required. The session in which the transaction to roll back is running.
  string session = 1;

  // Required. The transaction to roll back.
  bytes transaction_id = 2;
}