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
-
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 useread_timestamp (
datetime.datetime
) – Execute all reads at the given timestamp.exact_staleness (
datetime.timedelta
) – Execute all reads at a timestamp that isexact_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 usemapping (mapping) – serialized state of the instance
- Return type
-
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
ordict
) – (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 messageQueryOptions
- 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 retrievedindex (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
- 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
- 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
- Returns
a result set instance which can be used to consume rows.
-
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
-
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:- 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 ofBurstyPool
.
-
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
- 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 isexact_staleness
old.
- Return type
- Returns
new wrapper
-
create
()[source]¶ Create this database within its instance
Inclues any configured schema assigned to
ddl_statements
.- Return type
- 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
- 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
-
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
ordict
) – (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 messageQueryOptions
- Return type
- Returns
Count of rows affected by the DML statement.
-
exists
()[source]¶ Test whether this database exists.
- Return type
- 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
- 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
- Returns
True if the database state is READY, else False.
-
is_ready
()[source]¶ Test whether this database is ready for use.
- Return type
- 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
- Type
- 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
- Returns
The database name.
-
reload
()[source]¶ Reload this database.
Refresh any configured schema into
ddl_statements
.- 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
- 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
.
-
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.
- Parameters
- Return type
- 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
.- Parameters
- Return type
- 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