Features

• Breaking: Session.run_in_transaction returns the callback's return value
  instead of the committed timestamp. (session.run_in_transaction returns the callback's return value. #3753)
• Block creation of transaction for Session with existing transaction. (Block creation of transaction for session w/ existing txn. #3785)
• Breaking: Remove Database.read and Database.execute_sql convenience methods. (Drop 'Database.read' and 'Database.execute_sql' convenience methods. #3787)
• Add a .one and .one_or_none method on StreamedResultSet. (Spanner: Add a .one and .one_or_none method. #3784)

Implementation

• Make __eq__ and __ne__ work correctly with "unknown" types. (Fix __eq__ and __ne__. #3765)
• Bug-fix: Re-use explicit credentials when creating database.spanner_api. (Reuse explicit credentials when creating 'database.spanner_api'. #3722)
  commit fe757be
• Bug-fix: Catch both a GaxError and _Rendezvous (from grpcio) for failures in run_in_transaction ( Add a test which provokes abort-during-read during 'run_in_transaction'. #3663)
• Prevent nested transactions. (Prevent nested transactions. #3789)

Docs

• Improve the Spanner README. (Make the Spanner README better. #3791, Fix Spanner README. #3796)
• Drop Session as a promoted, top-level entity in docs. (Drop 'Session' as a promoted, top-level entity in docs. #3792)

Dependencies

• Updating google-cloud-core ~= 0.27 (Bump core version number #3864)
• google.cloud.iterator moved to google.api.core.page_iterator (Move google.cloud.iterator to google.api.core.page_iterator #3770)
• Using google.api.core.future instead of google.cloud.future (Move google.cloud.future to google.api.core #3764)

PyPI: https://pypi.org/project/google-cloud-spanner/0.27.0/

https://circleci.com/gh/GoogleCloudPlatform/google-cloud-python/3103

Build predictably failed. Manually pushed to PyPI: https://pypi.org/project/google-cloud-spanner/0.27.0/

https://github.com/GoogleCloudPlatform/google-cloud-python/releases/tag/spanner-0.27.0