batch-usage.rst

Batching Modifications

A :class:`~google.cloud.spanner_v1.batch.Batch` represents a set of data modification operations to be performed on tables in a database. Use of a Batch does not require creating an explicit :class:`~google.cloud.spanner_v1.snapshot.Snapshot` or :class:`~google.cloud.spanner_v1.transaction.Transaction`. Until :meth:`~google.cloud.spanner_v1.batch.Batch.commit` is called on a Batch, no changes are propagated to the back-end.

Use Batch via BatchCheckout

:meth:`Database.batch` creates a :class:`~google.cloud.spanner_v1.database.BatchCheckout` instance to use as a context manager to handle creating and committing a :class:`~google.cloud.spanner_v1.batch.Batch`. The :class:`BatchCheckout` will automatically call :meth:`~google.cloud.spanner_v1.batch.Batch.commit` if the with block exits without raising an exception.

from google.cloud.spanner import KeySet

client = spanner.Client()
instance = client.instance(INSTANCE_NAME)
database = instance.database(DATABASE_NAME)

to_delete = KeySet(keys=[
    ('[email protected]',)
    ('[email protected]',)
])

with database.batch() as batch:

    batch.insert(
        'citizens', columns=['email', 'first_name', 'last_name', 'age'],
        values=[
            ['[email protected]', 'Phred', 'Phlyntstone', 32],
            ['[email protected]', 'Bharney', 'Rhubble', 31],
        ])

    batch.update(
        'citizens', columns=['email', 'age'],
        values=[
            ['[email protected]', 33],
            ['[email protected]', 32],
        ])

    ...

    batch.delete('citizens', to_delete)

Inserting records using a Batch

:meth:`Batch.insert` adds one or more new records to a table. This fails if any of the records already exist.

batch.insert(
    'citizens', columns=['email', 'first_name', 'last_name', 'age'],
    values=[
        ['[email protected]', 'Phred', 'Phlyntstone', 32],
        ['[email protected]', 'Bharney', 'Rhubble', 31],
    ])

Note

Ensure that data being sent for STRING columns uses a text string (str in Python 3; unicode in Python 2).

Additionally, if you are writing data intended for a BYTES column, you must base64 encode it.

Update records using a Batch

:meth:`Batch.update` updates one or more existing records in a table. This fails if any of the records do not already exist.

batch.update(
    'citizens', columns=['email', 'age'],
    values=[
        ['[email protected]', 33],
        ['[email protected]', 32],
    ])

Note

Ensure that data being sent for STRING columns uses a text string (str in Python 3; unicode in Python 2).

Additionally, if you are writing data intended for a BYTES column, you must base64 encode it.

Insert or update records using a Batch

:meth:`Batch.insert_or_update` inserts or updates one or more records in a table. Existing rows have values for the supplied columns overwritten; other column values are preserved.

batch.insert_or_update(
    'citizens', columns=['email', 'first_name', 'last_name', 'age'],
    values=[
        ['[email protected]', 'Phred', 'Phlyntstone', 31],
        ['[email protected]', 'Wylma', 'Phlyntstone', 29],
    ])

Note

Ensure that data being sent for STRING columns uses a text string (str in Python 3; unicode in Python 2).

Additionally, if you are writing data intended for a BYTES column, you must base64 encode it.

Replace records using a Batch

:meth:`Batch.replace` inserts or updates one or more records in a table. Existing rows have values for the supplied columns overwritten; other column values are set to null.

batch.replace(
    'citizens', columns=['email', 'first_name', 'last_name', 'age'],
    values=[
        ['[email protected]', 'Bharney', 'Rhubble', 30],
        ['[email protected]', 'Bhettye', 'Rhubble', 30],
    ])

Note

Ensure that data being sent for STRING columns uses a text string (str in Python 3; unicode in Python 2).

Additionally, if you are writing data intended for a BYTES column, you must base64 encode it.

Delete records using a Batch

:meth:`Batch.delete` removes one or more records from a table. Attempting to delete rows that do not exist will not cause errors.

from google.cloud.spanner import KeySet

to_delete = KeySet(keys=[
    ('[email protected]',)
    ('[email protected]',)
])

batch.delete('citizens', to_delete)

Commit changes for a Batch

After describing the modifications to be made to table data via the :meth:`Batch.insert`, :meth:`Batch.update`, :meth:`Batch.insert_or_update`, :meth:`Batch.replace`, and :meth:`Batch.delete` methods above, send them to the back-end by calling :meth:`Batch.commit`, which makes the Commit API call.

You do not need to call this yourself as :class:`~google.cloud.spanner_v1.database.BatchCheckout` will call this method automatically upon exiting the with block.

batch.commit()

Next Step

Next, learn about :doc:`snapshot-usage`.