Struct MultiUseReadOnlyTransactionBuilder 

pub struct MultiUseReadOnlyTransactionBuilder { /* private fields */ }

A builder for MultiUseReadOnlyTransaction.

Example

let db_client = spanner.database_client("projects/p/instances/i/databases/d").build().await?;
let read_only_tx = db_client.read_only_transaction()
    .set_timestamp_bound(TimestampBound::strong())
    .build()
    .await?;

Implementations

impl MultiUseReadOnlyTransactionBuilder

pub fn with_begin_transaction_option( self, option: BeginTransactionOption, ) -> Self

Sets the option for how to start a transaction.

Example

let db_client = spanner.database_client("projects/p/instances/i/databases/d").build().await?;
let transaction = db_client.read_only_transaction().with_begin_transaction_option(BeginTransactionOption::ExplicitBegin).build().await?;
let statement = Statement::builder("SELECT * FROM users").build();
let result_set = transaction.execute_query(statement).await?;

By default, the Spanner client will inline the BeginTransaction call with the first query in the transaction. This reduces the number of round-trips to Spanner that are needed for a transaction. Setting this option to ExplicitBegin can be beneficial for specific transaction shapes:

1. When the transaction executes multiple parallel queries at the start of the transaction. Only one query can include a BeginTransaction option, and all other queries must wait for the first query to return the first result before they can proceed to execute. A BeginTransaction RPC will quickly return a transaction ID and allow all queries to start execution in parallel once the transaction ID has been returned.
2. When the first query in the transaction could fail. If the query fails, then it will also not start a transaction and return a transaction ID. The transaction will then fall back to executing a BeginTransaction RPC and retry the first query.

Default is BeginTransactionOption::InlineBegin.

pub fn with_begin_attempt_timeout(self, timeout: Duration) -> Self

Sets the per-attempt timeout for the BeginTransaction RPC.

Example

let db_client = spanner.database_client("projects/p/instances/i/databases/d").build().await?;
let transaction = db_client.read_only_transaction()
    .with_begin_attempt_timeout(Duration::from_secs(10))
    .build()
    .await?;

Note: This timeout is only used if the transaction uses the ExplicitBegin transaction option.

pub fn with_begin_retry_policy(self, policy: impl Into<RetryPolicyArg>) -> Self

Sets the retry policy for the BeginTransaction RPC.

Example

let db_client = spanner.database_client("projects/p/instances/i/databases/d").build().await?;
let transaction = db_client.read_only_transaction()
    .with_begin_retry_policy(NeverRetry)
    .build()
    .await?;

Note: This policy is only used if the transaction uses the ExplicitBegin transaction option.

pub fn with_begin_backoff_policy( self, policy: impl Into<BackoffPolicyArg>, ) -> Self

Sets the backoff policy for the BeginTransaction RPC.

Example

let db_client = spanner.database_client("projects/p/instances/i/databases/d").build().await?;
let transaction = db_client.read_only_transaction()
    .with_begin_backoff_policy(ExponentialBackoff::default())
    .build()
    .await?;

Note: This policy is only used if the transaction uses the ExplicitBegin transaction option.

pub fn set_timestamp_bound(self, bound: TimestampBound) -> Self

Sets the timestamp bound for the read-only transaction.

Example

let db_client = spanner.database_client("projects/p/instances/i/databases/d").build().await?;
let builder = db_client.read_only_transaction().set_timestamp_bound(TimestampBound::strong());

pub async fn build(self) -> Result<MultiUseReadOnlyTransaction>

Builds the MultiUseReadOnlyTransaction and starts the transaction by calling the BeginTransaction RPC.

Example

let db_client = spanner.database_client("projects/p/instances/i/databases/d").build().await?;
let tx = db_client.read_only_transaction().build().await?;