Database API

User friendly container for Cloud Spanner Database.

class google.cloud.spanner_v1.database.BatchCheckout(database, request_options=None)

Bases: object

Context manager for using a batch from a database.

Inside the context manager, checks out a session from the database, creates a batch from it, making the batch available.

Caller must not use the batch to perform API requests outside the scope of the context manager.

Parameters
- database( Database ) – database to use
- request_options( google.cloud.spanner_v1.types.RequestOptions ) – (Optional) Common options for the commit request. If a dict is provided, it must be of the same form as the protobuf message RequestOptions .

_ enter_ ()

Begin with block.

_ exit_ (exc_type, exc_val, exc_tb)

End with block.

class google.cloud.spanner_v1.database.BatchSnapshot(database, read_timestamp=None, exact_staleness=None)

Bases: object

Wrapper for generating and processing read / query batches.

Parameters
- database( Database ) – database to use
- read_timestamp( datetime.datetime ) – Execute all reads at the given timestamp.
- exact_staleness( datetime.timedelta ) – Execute all reads at a timestamp that is exact_staleness old.

close()

Clean up underlying session.

NOTE: If the transaction has been shared across multiple machines, calling this on any machine would invalidate the transaction everywhere. Ideally this would be called when data has been read from all the partitions.

execute_sql(*args, **kw)

Convenience method: perform query operation via snapshot.

See execute_sql() .

classmethod from_dict(database, mapping)

Reconstruct an instance from a mapping.

Parameters
- database( Database ) – database to use
- mapping( mapping ) – serialized state of the instance
Return type

BatchSnapshot

generate_query_batches(sql, params=None, param_types=None, partition_size_bytes=None, max_partitions=None, query_options=None, *, retry=<_MethodDefault._DEFAULT_VALUE:

Start a partitioned query operation.

Uses the PartitionQuery API request to start a partitioned query operation. Returns a list of batch information needed to perform the actual queries.

Parameters
- sql( str ) – SQL query statement
- params( dict , **{str -> column value} ) – values for parameter replacement. Keys must match the names used in sql .
- param_types( dict [ str -> Union [ dict , *[ types.Type ](spanner_v1/types.md#google.cloud.spanner_v1.types.Type) ] *] ) – (Optional) maps explicit types for one or more param values; required if parameters are passed.
- partition_size_bytes( int ) – (Optional) desired size for each partition generated. The service uses this as a hint, the actual partition size may differ.
- partition_size_bytes– (Optional) desired size for each partition generated. The service uses this as a hint, the actual partition size may differ.
- max_partitions( int ) – (Optional) desired maximum number of partitions generated. The service uses this as a hint, the actual number of partitions may differ.
- query_options( QueryOptions or dict ) – (Optional) Query optimizer configuration to use for the given query. If a dict is provided, it must be of the same form as the protobuf message QueryOptions
- retry( Retry ) – (Optional) The retry settings for this request.
- timeout( float ) – (Optional) The timeout for this request.
Return type

iterable of dict
Returns

mappings of information used perform actual partitioned reads via process_read_batch() .

generate_read_batches(table, columns, keyset, index='', partition_size_bytes=None, max_partitions=None, *, retry=<_MethodDefault._DEFAULT_VALUE:

Start a partitioned batch read operation.

Uses the PartitionRead API request to initiate the partitioned read. Returns a list of batch information needed to perform the actual reads.

Parameters
- table( str ) – name of the table from which to fetch data
- columns( list of str ) – names of columns to be retrieved
- keyset( KeySet ) – keys / ranges identifying rows to be retrieved
- index( str ) – (Optional) name of index to use, rather than the table’s primary key
- partition_size_bytes( int ) – (Optional) desired size for each partition generated. The service uses this as a hint, the actual partition size may differ.
- max_partitions( int ) – (Optional) desired maximum number of partitions generated. The service uses this as a hint, the actual number of partitions may differ.
- retry( Retry ) – (Optional) The retry settings for this request.
- timeout( float ) – (Optional) The timeout for this request.
Return type

iterable of dict
Returns

mappings of information used perform actual partitioned reads via process_read_batch() .

process(batch)

Process a single, partitioned query or read.

Parameters

batch( mapping ) – one of the mappings returned from an earlier call to generate_query_batches() .
Return type

StreamedResultSet
Returns

a result set instance which can be used to consume rows.
Raises

ValueError – if batch does not contain either ‘read’ or ‘query’

process_query_batch(batch, *, retry=<_MethodDefault._DEFAULT_VALUE:

Process a single, partitioned query.

Parameters
- batch( mapping ) – one of the mappings returned from an earlier call to generate_query_batches() .
- retry( Retry ) – (Optional) The retry settings for this request.
- timeout( float ) – (Optional) The timeout for this request.
Return type

StreamedResultSet
Returns

a result set instance which can be used to consume rows.

process_read_batch(batch, *, retry=<_MethodDefault._DEFAULT_VALUE:

Process a single, partitioned read.

Parameters
- batch( mapping ) – one of the mappings returned from an earlier call to generate_read_batches() .
- retry( Retry ) – (Optional) The retry settings for this request.
- timeout( float ) – (Optional) The timeout for this request.
Return type

StreamedResultSet
Returns

a result set instance which can be used to consume rows.

read(*args, **kw)

Convenience method: perform read operation via snapshot.

See read() .

to_dict()

Return state as a dictionary.

Result can be used to serialize the instance and reconstitute it later using from_dict() .

Return type

dict

class google.cloud.spanner_v1.database.Database(database_id, instance, ddl_statements=(), pool=None, logger=None, encryption_config=None)

Bases: object

Representation of a Cloud Spanner Database.

We can use a Database to:

create() the database
reload() the database
update() the database
drop() the database
Parameters
- database_id( str ) – The ID of the database.
- instance( Instance ) – The instance that owns the database.
- ddl_statements( list of string ) – (Optional) DDL statements, excluding the CREATE DATABASE statement.
- pool(concrete subclass of AbstractSessionPool .) – (Optional) session pool to be used by database. If not passed, the database will construct an instance of BurstyPool .
- logger( logging.Logger ) – (Optional) a custom logger that is used if log_commit_stats is True to log commit statistics. If not passed, a logger will be created when needed that will log the commit statistics to stdout.
- encryption_config( EncryptionConfig or RestoreDatabaseEncryptionConfig or dict ) – (Optional) Encryption configuration for the database. If a dict is provided, it must be of the same form as either of the protobuf messages EncryptionConfig or RestoreDatabaseEncryptionConfig

batch(request_options=None)

Return an object which wraps a batch.

The wrapper must be used as a context manager, with the batch as the value returned by the wrapper.

Parameters

request_options( google.cloud.spanner_v1.types.RequestOptions ) – (Optional) Common options for the commit request. If a dict is provided, it must be of the same form as the protobuf message RequestOptions .
Return type

BatchCheckout
Returns

new wrapper

batch_snapshot(read_timestamp=None, exact_staleness=None)

Return an object which wraps a batch read / query.

Parameters
- read_timestamp( datetime.datetime ) – Execute all reads at the given timestamp.
- exact_staleness( datetime.timedelta ) – Execute all reads at a timestamp that is exact_staleness old.
Return type

BatchSnapshot
Returns

new wrapper

create()

Create this database within its instance

Includes any configured schema assigned to ddl_statements .

See https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.database.v1#google.spanner.admin.database.v1.DatabaseAdmin.CreateDatabase

Return type

Operation
Returns

a future used to poll the status of the create request
Raises
- Conflict– if the database already exists
- NotFound– if the instance owning the database does not exist

property create_time()

Create time of this database.

Return type

datetime.datetime
Returns

a datetime object representing the create time of this database

property ddl_statements()

DDL Statements used to define database schema.

See cloud.google.com/spanner/docs/data-definition-language

Return type

sequence of string
Returns

the statements

property default_leader()

The read-write region which contains the database’s leader replicas.

Return type

str
Returns

a string representing the read-write region

drop()

Drop this database.

See https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.database.v1#google.spanner.admin.database.v1.DatabaseAdmin.DropDatabase

property earliest_version_time()

The earliest time at which older versions of the data can be read.

Return type

datetime.datetime
Returns

a datetime object representing the earliest version time

property encryption_config()

Encryption config for this database. :rtype: EncryptionConfig :returns: an object representing the encryption config for this database

property encryption_info()

Encryption info for this database. :rtype: a list of EncryptionInfo :returns: a list of objects representing encryption info for this database

execute_partitioned_dml(dml, params=None, param_types=None, query_options=None, request_options=None)

Execute a partitionable DML statement.

Parameters
- dml( str ) – DML statement
- params( dict , **{str -> column value} ) – values for parameter replacement. Keys must match the names used in dml .
- param_types( dict [ str -> Union [ dict , *[ types.Type ](spanner_v1/types.md#google.cloud.spanner_v1.types.Type) ] *] ) – (Optional) maps explicit types for one or more param values; required if parameters are passed.
- query_options( QueryOptions or dict ) – (Optional) Query optimizer configuration to use for the given query. If a dict is provided, it must be of the same form as the protobuf message QueryOptions
- request_options( google.cloud.spanner_v1.types.RequestOptions ) – (Optional) Common options for this request. If a dict is provided, it must be of the same form as the protobuf message RequestOptions .
Return type

int
Returns

Count of rows affected by the DML statement.

exists()

Test whether this database exists.

See https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.database.v1#google.spanner.admin.database.v1.DatabaseAdmin.GetDatabaseDDL

Return type

bool
Returns

True if the database exists, else false.

classmethod from_pb(database_pb, instance, pool=None)

Creates an instance of this class from a protobuf.

Parameters
- database_pb( Instance ) – A instance protobuf object.
- instance( Instance ) – The instance that owns the database.
- pool(concrete subclass of AbstractSessionPool .) – (Optional) session pool to be used by database.
Return type

Database
Returns

The database parsed from the protobuf response.
Raises

ValueError – if the instance name does not match the expected format or if the parsed project ID does not match the project ID on the instance’s client, or if the parsed instance ID does not match the instance’s ID.

is_optimized()

Test whether this database has finished optimizing.

Return type

bool
Returns

True if the database state is READY, else False.

is_ready()

Test whether this database is ready for use.

Return type

bool
Returns

True if the database state is READY_OPTIMIZING or READY, else False.

list_database_operations(filter_='', page_size=None)

List database operations for the database.

Parameters
- filter( str ) – Optional. A string specifying a filter for which database operations to list.
- page_size( int ) – Optional. The maximum number of operations in each page of results from this request. Non-positive values are ignored. Defaults to a sensible value set by the API.
Type

Iterator
Returns

Iterator of Operation resources within the current instance.

list_tables()

List tables within the database.

Type

Iterable
Returns

Iterable of Table resources within the current database.

property logger()

Logger used by the database.

The default logger will log commit stats at the log level INFO using sys.stderr.

Return type

logging.Logger or None
Returns

the logger

property name()

Database name used in requests.

NOTE: This property will not change if database_id does not, but the return value is not cached.

The database name is of the form

"projects/../instances/../databases/{database_id}"

Return type

str
Returns

The database name.

reload()

Reload this database.

Refresh any configured schema into ddl_statements .

See https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.database.v1#google.spanner.admin.database.v1.DatabaseAdmin.GetDatabaseDDL

Raises

NotFound– if the database does not exist

restore(source)

Restore from a backup to this database.

Parameters

source( Backup ) – the path of the source being restored from.
Return type

Operation
Returns

a future used to poll the status of the create request
Raises
- Conflict– if the database already exists
- NotFound– if the instance owning the database does not exist, or if the backup being restored from does not exist
- ValueError – if backup is not set

property restore_info()

Restore info for this database.

Return type

RestoreInfo
Returns

an object representing the restore info for this database

run_in_transaction(func, *args, **kw)

Perform a unit of work in a transaction, retrying on abort.

Parameters
- func( callable ) – takes a required positional argument, the transaction, and additional positional / keyword arguments as supplied by the caller.
- args( tuple ) – additional positional arguments to be passed to func .
- kw( dict ) – (Optional) keyword arguments to be passed to func . If passed, “timeout_secs” will be removed and used to override the default retry timeout which defines maximum timestamp to continue retrying the transaction.
Return type

Any
Returns

The return value of func .
Raises

Exception – reraises any non-ABORT exceptions raised by func .

session(labels=None)

Factory to create a session for this database.

Parameters

labels( dict * ( str -> str) or [ None*]( https://python.readthedocs.io/en/latest/library/constants.html#None )) – (Optional) user-assigned labels for the session.
Return type

Session
Returns

a session bound to this database.

snapshot(**kw)

Return an object which wraps a snapshot.

The wrapper must be used as a context manager, with the snapshot as the value returned by the wrapper.

See https://cloud.google.com/spanner/reference/rpc/google.spanner.v1#google.spanner.v1.TransactionOptions.ReadOnly

Parameters

kw( dict ) – Passed through to Snapshot constructor.
Return type

SnapshotCheckout
Returns

new wrapper

property spanner_api()

Helper for session-related API calls.

property state()

State of this database.

Return type

State
Returns

an enum describing the state of the database

table(table_id)

Factory to create a table object within this database.

Note: This method does not create a table in Cloud Spanner, but it can be used to check if a table exists.

 my_table = database.table("my_table")
if my_table.exists():
    print("Table with ID 'my_table' exists.")
else:
    print("Table with ID 'my_table' does not exist.")

Parameters

table_id( str ) – The ID of the table.
Return type

Table
Returns

a table owned by this database.

update_ddl(ddl_statements, operation_id='')

Update DDL for this database.

Apply any configured schema from ddl_statements .

See https://cloud.google.com/spanner/reference/rpc/google.spanner.admin.database.v1#google.spanner.admin.database.v1.DatabaseAdmin.UpdateDatabase

Parameters
- ddl_statements( Sequence [ str ] ) – a list of DDL statements to use on this database
- operation_id( str ) – (optional) a string ID for the long-running operation
Return type

google.api_core.operation.Operation
Returns

an operation instance
Raises

NotFound– if the database does not exist

property version_retention_period()

The period in which Cloud Spanner retains all versions of data for the database.

Return type

str
Returns

a string representing the duration of the version retention period

class google.cloud.spanner_v1.database.SnapshotCheckout(database, **kw)

Bases: object

Context manager for using a snapshot from a database.

Inside the context manager, checks out a session from the database, creates a snapshot from it, making the snapshot available.

Caller must not use the snapshot to perform API requests outside the scope of the context manager.

Parameters
- database( Database ) – database to use
- kw( dict ) – Passed through to Snapshot constructor.

_ enter_ ()

Begin with block.

_ exit_ (exc_type, exc_val, exc_tb)

End with block.