Struct google_api_proto::google::spanner::executor::v1::StartBatchTransactionAction

pub struct StartBatchTransactionAction {
    pub cloud_database_role: String,
    pub param: Option<Param>,
}

Starts a batch read-only transaction in executor. Successful outcomes of this action will contain batch_txn_id–the identificator that can be used to start the same transaction in other Executors to parallelize partition processing.

Example of a batch read flow:

1. Start batch transaction with a timestamp (StartBatchTransactionAction)
2. Generate database partitions for a read or query (GenerateDbPartitionsForReadAction/GenerateDbPartitionsForQueryAction)
3. Call ExecutePartitionAction for some or all partitions, process rows
4. Clean up the transaction (CloseBatchTransactionAction).

More sophisticated example, with parallel processing:

1. Start batch transaction with a timestamp (StartBatchTransactionAction), note the returned BatchTransactionId
2. Generate database partitions for a read or query (GenerateDbPartitionsForReadAction/GenerateDbPartitionsForQueryAction)
3. Distribute the partitions over a pool of workers, along with the transaction ID.

In each worker: 4-1. StartBatchTransactionAction with the given transaction ID 4-2. ExecutePartitionAction for each partition it got, process read results 4-3. Close (not cleanup) the transaction (CloseBatchTransactionAction).

When all workers are done: 5. Cleanup the transaction (CloseBatchTransactionAction). This can be done either by the last worker to finish the job, or by the main Executor that initialized this transaction in the first place. It is also possible to clean it up with a brand new Executor – just execute StartBatchTransactionAction with the ID, then clean it up right away.

Cleaning up is optional, but recommended.

Fields

cloud_database_role: String

Database role to assume while performing this action. Setting the database_role will enforce additional role-based access checks on this action.

param: Option<Param>

To start a new transaction, specify an exact timestamp. Alternatively, an existing batch transaction ID can be used. Either one of two must be set.

Trait Implementations

impl Clone for StartBatchTransactionAction

fn clone(&self) -> StartBatchTransactionAction

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StartBatchTransactionAction

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for StartBatchTransactionAction

fn default() -> Self

Returns the “default value” for a type.

impl Message for StartBatchTransactionAction

fn encoded_len(&self) -> usize

Returns the encoded length of the message without a length delimiter.

fn clear(&mut self)

Clears the message, resetting all fields to their default.

fn encode(&self, buf: &mut impl BufMut) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message to a buffer.

fn encode_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message to a newly allocated buffer.

fn encode_length_delimited( &self, buf: &mut impl BufMut, ) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message with a length-delimiter to a buffer.

fn encode_length_delimited_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message with a length-delimiter to a newly allocated buffer.

fn decode(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes an instance of the message from a buffer.

fn decode_length_delimited(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes a length-delimited instance of the message from the buffer.

fn merge(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes an instance of the message from a buffer, and merges it into self.

fn merge_length_delimited(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes a length-delimited instance of the message from buffer, and merges it into self.

impl PartialEq for StartBatchTransactionAction

fn eq(&self, other: &StartBatchTransactionAction) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for StartBatchTransactionAction