Class: Google::Spanner::V1::TransactionOptions::ReadOnly

Inherits:
Object
  • Object
show all
Defined in:
lib/google/cloud/spanner/v1/doc/google/spanner/v1/transaction.rb

Overview

Options for read-only transactions.

Instance Attribute Summary collapse

Instance Attribute Details

#exact_staleness ⇒ Google::Protobuf::Duration

Returns Executes all reads at a timestamp that is exact_staleness old. The timestamp is chosen soon after the read is started.

Guarantees that all writes that have committed more than the specified number of seconds ago are visible. Because Cloud Spanner chooses the exact timestamp, this mode works even if the client’s local clock is substantially skewed from Cloud Spanner commit timestamps.

Useful for reading at nearby replicas without the distributed timestamp negotiation overhead of max_staleness.

Returns:

  • (Google::Protobuf::Duration) —

    Executes all reads at a timestamp that is exact_staleness old. The timestamp is chosen soon after the read is started.

    Guarantees that all writes that have committed more than the specified number of seconds ago are visible. Because Cloud Spanner chooses the exact timestamp, this mode works even if the client’s local clock is substantially skewed from Cloud Spanner commit timestamps.

    Useful for reading at nearby replicas without the distributed timestamp negotiation overhead of max_staleness.



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# File 'lib/google/cloud/spanner/v1/doc/google/spanner/v1/transaction.rb', line 309

class ReadOnly; end

#max_staleness ⇒ Google::Protobuf::Duration

Returns Read data at a timestamp >= NOW - max_staleness seconds. Guarantees that all writes that have committed more than the specified number of seconds ago are visible. Because Cloud Spanner chooses the exact timestamp, this mode works even if the client’s local clock is substantially skewed from Cloud Spanner commit timestamps.

Useful for reading the freshest data available at a nearby replica, while bounding the possible staleness if the local replica has fallen behind.

Note that this option can only be used in single-use transactions.

Returns:

  • (Google::Protobuf::Duration) —

    Read data at a timestamp >= NOW - max_staleness seconds. Guarantees that all writes that have committed more than the specified number of seconds ago are visible. Because Cloud Spanner chooses the exact timestamp, this mode works even if the client’s local clock is substantially skewed from Cloud Spanner commit timestamps.

    Useful for reading the freshest data available at a nearby replica, while bounding the possible staleness if the local replica has fallen behind.

    Note that this option can only be used in single-use transactions.



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# File 'lib/google/cloud/spanner/v1/doc/google/spanner/v1/transaction.rb', line 309

class ReadOnly; end

#min_read_timestamp ⇒ Google::Protobuf::Timestamp

Returns Executes all reads at a timestamp >= min_read_timestamp.

This is useful for requesting fresher data than some previous read, or data that is fresh enough to observe the effects of some previously committed transaction whose timestamp is known.

Note that this option can only be used in single-use transactions.

Returns:

  • (Google::Protobuf::Timestamp) —

    Executes all reads at a timestamp >= min_read_timestamp.

    This is useful for requesting fresher data than some previous read, or data that is fresh enough to observe the effects of some previously committed transaction whose timestamp is known.

    Note that this option can only be used in single-use transactions.



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# File 'lib/google/cloud/spanner/v1/doc/google/spanner/v1/transaction.rb', line 309

class ReadOnly; end

#read_timestamp ⇒ Google::Protobuf::Timestamp

Returns Executes all reads at the given timestamp. Unlike other modes, reads at a specific timestamp are repeatable; the same read at the same timestamp always returns the same data. If the timestamp is in the future, the read will block until the specified timestamp, modulo the read’s deadline.

Useful for large scale consistent reads such as mapreduces, or for coordinating many reads against a consistent snapshot of the data.

Returns:

  • (Google::Protobuf::Timestamp) —

    Executes all reads at the given timestamp. Unlike other modes, reads at a specific timestamp are repeatable; the same read at the same timestamp always returns the same data. If the timestamp is in the future, the read will block until the specified timestamp, modulo the read’s deadline.

    Useful for large scale consistent reads such as mapreduces, or for coordinating many reads against a consistent snapshot of the data.



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# File 'lib/google/cloud/spanner/v1/doc/google/spanner/v1/transaction.rb', line 309

class ReadOnly; end

#return_read_timestamp ⇒ true, false

Returns If true, the Cloud Spanner-selected read timestamp is included in the Transaction message that describes the transaction.

Returns:

  • (true, false) —

    If true, the Cloud Spanner-selected read timestamp is included in the Transaction message that describes the transaction.



309
 
# File 'lib/google/cloud/spanner/v1/doc/google/spanner/v1/transaction.rb', line 309

class ReadOnly; end

#strong ⇒ true, false

Returns Read at a timestamp where all previously committed transactions are visible.

Returns:

  • (true, false) —

    Read at a timestamp where all previously committed transactions are visible.



309
 
# File 'lib/google/cloud/spanner/v1/doc/google/spanner/v1/transaction.rb', line 309

class ReadOnly; end