#479: on_table_exists=skip option for table materialization

[choyrim]

implements on_table_exists=skip option

instead of creating the table, it simply executes "select 1"

resolves #479

As requested by @damian3031 in his feedback, a revised checklist:

• Rebase onto master, as CI failures have been fixed there.
• Remove .changes/1.10.0.md file and revert changes to CHANGELOG.md.
• move feature test case to bottom of relevant file.
• additional assertions in tests
• simplify adapter CTAS logic
• add a changie file by running changie new.
• Squash commits into a single one.
• Install and run pre-commit checks before committing your changes.

[choyrim]

added a change to use "CREATE TABLE IF NOT EXISTS" to do the skipping instead of "SELECT 1"

this makes it so that the generated SQL is more useful.

[damian3031]

Thank you for your contribution! Some remarks:

1. Remove .changes/1.10.0.md file and revert changes to CHANGELOG.md. Instead, add a changie file by running changie new.
2. Squash commits into a single one.
3. Rebase onto master, as CI failures have been fixed there.
4. Install and run pre-commit checks before committing your changes.

[choyrim]

@damian3031 thank you for your feedback. i believe i have resolved the issues you raised.

i've run tox -r and pre-commit run --all-files and the tools seem happy.

i am also happy to add documentation. but it wasn't clear to me where to add the documentation.

[damian3031]

@choyrim Thanks for your work!

Regarding documentation, it is hosted by dbt, you need to create PR to make change here.

Please add skip strategy after replace and tag me in a PR.

[choyrim]

@choyrim Thanks for your work!

Regarding documentation, it is hosted by dbt, you need to create PR to make change here.

Please add skip strategy after replace and tag me in a PR.

@damian3031

sorry for the delay. I need to do some administrative formalities before I can contribute to the doc project. I will take care of those formalities soon and tag you in a PR in two weeks or so.

[choyrim]

@damian3031 tagged you in the docs.getdbt.com PR.