support archival (and incremental models?) on BigQuery

[drewbanin]

This is possible with the recent improvements to BigQuery's DML interface

[drewbanin]

TODO : Confirm that this works, then close

[lewish]

Great work on the merge statements! Just doing some testing with these, and ran into a couple of small issues:

The stripped whitespace in Jinja when not using unique_key causes some syntax errors, ends up generating some SQL like as SOURCEon FALSE

BigQuery currently throws an internal exception when using ON FALSE on conjunction with WHEN MATCHED then.

I filed a bug but probably make sense to only put the WHEN MATCHED clause in if the unique_key is specified.

An example of the fixes I made here: lewish@393d6fc#diff-b09ed71a27c521a23e10d94e0fa8195d

[cmcarthur]

@lewish this is great. can you send a PR with those changes? the only thing i'm unsure about is only including WHEN MATCHED when unique key is specified -- I'll discuss w @drewbanin later today

[drewbanin]

great catches - thanks for the heads up, @lewish!