Fix ReadAllFromBigQuery leak temp dataset

[Abacn]

Caught by CleanupGCPResource workflow. There are many stale "bq_read_all_" datasets in the test project.

There is a consistent temp dataset leaking for Python SDK's ReadAllFromBigQuery. Each run will leave an empty dataset prefixed "bq_read_all_"

Cause:

• ReadFromBigQuery sets a default dataset of prefix "bq_read_all_"

beam/sdks/python/apache_beam/io/gcp/bigquery_read_internal.py

Line 215 in faff55c

self.temp_dataset = temp_dataset or 'bq_read_all_%s' % uuid.uuid4().hex

• BigQueryWrapper thinks this is a user configured dataset and won't delete it

beam/sdks/python/apache_beam/io/gcp/bigquery_tools.py

Line 895 in faff55c

not self.temp_dataset_id.startswith(self.TEMP_DATASET))

Solution:

Remove the prefix so BigQueryWrapper will use the default temp_dataset_* prefix and will delete it when clean_up_temporary_dataset called

However, this will now create each dataset for each element. To reduce the overload, move create/delete dataset into setup/teardown so that they are per worker basis.

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[Abacn]

Tested with
pytest -r s --log-cli-level=INFO --capture=no apache_beam/io/gcp/bigquery_read_it_test.py::ReadAllBQTests::test_read_queries --test-pipeline-options='--runner=DirectRunner --project=... --region=us-central1 --temp_location=gs://.../tmp'

Previously, there is a "bq_read_all..." dataset left

Now, it created one dataset

INFO     apache_beam.io.gcp.bigquery_tools:bigquery_tools.py:816 Dataset ...:beam_temp_dataset_f4dfd535a5ac4d4f9ccd961eb9a084fb does not exist so we will create it as temporary with location=US

and after test run, checked that this dataset no longer exists.

[Abacn]

in alignment with

beam/sdks/python/apache_beam/io/gcp/bigquery.py

Line 2961 in 0b61035

self.obj_id = '%d_%s' % (int(time.time()), secrets.token_hex(3))

likely the cause of #26343

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[Abacn]

R: @ahmedabu98

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[ahmedabu98]

Thanks for the fix! LGTM

[Abacn]

After this change there is still dataset leak. Found that on Dataflow runner DoFn.teardown is never called even if the job ended successfully (on Direct Runner, teardown is called, however).