As of January 1, 2020 this library no longer supports Python 2 on the latest released version. Library versions released prior to that date will continue to be available. For more information please visit Python 2 support on Google Cloud.

Database API¶

User friendly container for Cloud Spanner Database.

class google.cloud.spanner_v1.database.BatchCheckout(database)[source]¶

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

__enter__()[source]¶: Begin with block.

__exit__(exc_type, exc_val, exc_tb)[source]¶: End with block.

class google.cloud.spanner_v1.database.BatchSnapshot(database, read_timestamp=None, exact_staleness=None)[source]¶

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()[source]¶: 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)[source]¶

Convenience method: perform query operation via snapshot.

See execute_sql().

classmethod from_dict(database, mapping)[source]¶

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)[source]¶

Start a partitioned query operation.

Uses the PartitionQuery API request to start a partitioned query operation. Returns a list of batch information needed to peform 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]]) – (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

Return type

iterable of dict

Returns

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

generate_read_batches(table, columns, keyset, index='', partition_size_bytes=None, max_partitions=None)[source]¶

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.

Return type

iterable of dict

Returns

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

process(batch)[source]¶

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)[source]¶

Process a single, partitioned query.

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.

process_read_batch(batch)[source]¶

Process a single, partitioned read.

Parameters: batch (mapping) – one of the mappings returned from an earlier call to generate_read_batches().
Return type: StreamedResultSet
Returns: a result set instance which can be used to consume rows.

read(*args, **kw)[source]¶

Convenience method: perform read operation via snapshot.

See read().

to_dict()[source]¶

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)[source]¶

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.

batch()[source]¶

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.

Return type: BatchCheckout
Returns: new wrapper

batch_snapshot(read_timestamp=None, exact_staleness=None)[source]¶

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()[source]¶

Create this database within its instance

Inclues 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

drop()[source]¶

Drop this database.

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

execute_partitioned_dml(dml, params=None, param_types=None, query_options=None)[source]¶

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]]) – (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

Return type

int

Returns

Count of rows affected by the DML statement.

exists()[source]¶

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)[source]¶

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()[source]¶

Test whether this database has finished optimizing.

Return type: bool
Returns: True if the database state is READY, else False.

is_ready()[source]¶

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)[source]¶

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.

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()[source]¶

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)[source]¶

Restore from a backup to this database.

Parameters

backup (Backup) – the path of the backup 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)[source]¶

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 execptions raised by func.

session(labels=None)[source]¶

Factory to create a session for this database.

Parameters: labels (dict (str -> str) or None) – (Optional) user-assigned labels for the session.
Return type: Session
Returns: a session bound to this database.

snapshot(**kw)[source]¶

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

update_ddl(ddl_statements, operation_id='')[source]¶

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

class google.cloud.spanner_v1.database.SnapshotCheckout(database, **kw)[source]¶

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__()[source]¶: Begin with block.

__exit__(exc_type, exc_val, exc_tb)[source]¶: End with block.

Database API¶

google-cloud-spanner

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