Handle schema discovery of tables that are short-lived

[drdee]

Description of change

Some tables are short lived and they don't exist any more during the discovery phase.

This is the relevant stacktrace:

2020-03-04 16:50:05,457Z    tap - INFO fetching tables: 
2020-03-04 16:50:05,457Z    tap -    SELECT owner, table_name
2020-03-04 16:50:05,457Z    tap -    FROM all_tables
2020-03-04 16:50:05,457Z    tap -    WHERE owner != 'SYS' []
2020-03-04 16:50:12,206Z    tap - CRITICAL 'GL_POSTING_INTERIM_6872031'
2020-03-04 16:50:12,207Z    tap - Traceback (most recent call last):
2020-03-04 16:50:12,207Z    tap -   File "tap-env/bin/tap-oracle", line 8, in <module>
2020-03-04 16:50:12,207Z    tap -     sys.exit(main())
2020-03-04 16:50:12,207Z    tap -   File "/code/orchestrator/tap-env/lib/python3.5/site-packages/tap_oracle/__init__.py", line 572, in main
2020-03-04 16:50:12,207Z    tap -     raise exc
2020-03-04 16:50:12,208Z    tap -   File "/code/orchestrator/tap-env/lib/python3.5/site-packages/tap_oracle/__init__.py", line 569, in main
2020-03-04 16:50:12,208Z    tap -     main_impl()
2020-03-04 16:50:12,208Z    tap -   File "/code/orchestrator/tap-env/lib/python3.5/site-packages/tap_oracle/__init__.py", line 559, in main_impl
2020-03-04 16:50:12,208Z    tap -     do_discovery(conn_config, filter_schemas)
2020-03-04 16:50:12,208Z    tap -   File "/code/orchestrator/tap-env/lib/python3.5/site-packages/tap_oracle/__init__.py", line 331, in do_discovery
2020-03-04 16:50:12,208Z    tap -     'row_count': row_counts[table],

by using get and with a default value of 0 we can make the discovery phase more resilient.

Rollback steps

• revert this branch

[drdee]

@nick-mccoy @KAllan357 -- please have a look.