com.google.cloud.spanner

Interface Session

All Superinterfaces:

AutoCloseable, DatabaseClient

public interface Session
extends DatabaseClient, AutoCloseable

A Session can be used to perform transactions that read and/or modify data in a Cloud Spanner database.

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, or due to internal errors. If a session is deleted, requests to it return ErrorCode.NOT_FOUND.

Idle sessions can be kept alive by sending a trivial SQL query periodically, for example, SELECT 1.

Sessions are long-lived objects intended to be reused for many consecutive operations; a typical application will maintain a pool of sessions to use during its lifetime.

Since only one transaction can be performed at a time within any given session, instances require external synchronization; Session implementations are not required to be thread-safe.

Method Summary

Modifier and Type	Method and Description
void	close()
String	getName() Returns the resource name associated with this session.
void	prepareReadWriteTransaction() Prepares a transaction for use by a subsequent DatabaseClient.readWriteTransaction() or DatabaseClient.write(Iterable) call.

Methods inherited from interface com.google.cloud.spanner.DatabaseClient

executePartitionedUpdate, readOnlyTransaction, readOnlyTransaction, readWriteTransaction, singleUse, singleUse, singleUseReadOnlyTransaction, singleUseReadOnlyTransaction, transactionManager, write, writeAtLeastOnce

Method Detail

getName

String getName()

Returns the resource name associated with this session.

prepareReadWriteTransaction

void prepareReadWriteTransaction()

Prepares a transaction for use by a subsequent DatabaseClient.readWriteTransaction() or DatabaseClient.write(Iterable) call. It is not necessary to call this method before running a transaction or performing a write, but doing so may allow one round trip of the protocol to be performed in advance; calling this method on an idle session that is expected to execute a transaction or write in the near future may reduce the latency of the subsequent transaction/write.

close

void close()

Specified by:

close in interface AutoCloseable