Struct ConfiguredReadRequestBuilder 

pub struct ConfiguredReadRequestBuilder { /* private fields */ }

A fully configured read request that is ready to be built.

Implementations

impl ConfiguredReadRequestBuilder

pub fn set_limit(self, limit: i64) -> Self

Sets an optional limit on how many rows could be retrieved.

Example

let request = ReadRequest::builder("Users", vec!["Id"])
    .with_keys(KeySet::all())
    .set_limit(10)
    .build();

If fewer rows are found, only the matching rows will be returned.

pub fn set_request_tag(self, tag: impl Into<String>) -> Self

Sets the request tag to use for this read.

Example

let request = ReadRequest::builder("Users", vec!["Id"])
    .with_keys(KeySet::all())
    .set_request_tag("my-tag")
    .build();

See also: Troubleshooting with tags

pub fn set_priority(self, priority: Priority) -> Self

Sets the RPC priority to use for this read request.

Example

let request = ReadRequest::builder("Users", vec!["Id"])
    .with_keys(KeySet::all())
    .set_priority(Priority::Low)
    .build();

pub fn set_directed_read_options(self, options: DirectedReadOptions) -> Self

Sets the directed read options for this request.

let dro = DirectedReadOptions::default();
let req = ReadRequest::builder("MyTable", vec!["col1"])
    .with_keys(KeySet::all())
    .set_directed_read_options(dro)
    .build();

DirectedReadOptions can only be specified for a read-only transaction, otherwise Spanner returns an INVALID_ARGUMENT error.

pub fn set_order_by(self, order_by: OrderBy) -> Self

Sets the order in which rows are returned.

Example

let request = ReadRequest::builder("Users", vec!["Id"])
    .with_keys(KeySet::all())
    .set_order_by(OrderBy::NoOrder);

By default, Spanner returns result rows in primary key order (or index key order if reading via an index) except for PartitionRead requests.

For applications that don’t require rows to be returned in primary key (ORDER_BY_PRIMARY_KEY) order, setting ORDER_BY_NO_ORDER option allows Spanner to optimize row retrieval, resulting in lower latencies in certain cases (for example, bulk point lookups).

pub fn set_lock_hint(self, lock_hint: LockHint) -> Self

Sets the lock hint for this read.

Example

let request = ReadRequest::builder("Users", vec!["Id"])
    .with_keys(KeySet::all())
    .set_lock_hint(LockHint::Exclusive);

Lock hints can only be used with read-write transactions.

By default, Spanner acquires shared read locks, which allows other reads to still access the data until your transaction is ready to commit.

Requesting exclusive locks (LOCK_HINT_EXCLUSIVE) is beneficial if you observe high write contention. It prevents deadlocks by avoiding the situation where multiple transactions initially acquire shared locks and then both try to upgrade to exclusive locks at the same time.

Request exclusive locks judiciously because they block others from reading that data for the entire transaction, rather than just when the writes are being performed.

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

Sets the per-attempt timeout for this read request.

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

Sets the retry policy for this read request.

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

Sets the backoff policy for this read request.

pub fn build(self) -> ReadRequest

Builds the configured ReadRequest.

Trait Implementations

impl Clone for ConfiguredReadRequestBuilder

fn clone(&self) -> ConfiguredReadRequestBuilder

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ConfiguredReadRequestBuilder

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

Formats the value using the given formatter.