Increment models with RECURSIVE cause syntax error

[ccharlesgb]

Context

Caused by #45

When incremental models are dry runned they now check schema type compatibility with a merge statement. If the model SQL uses WITH RECURSIVE then this causes a syntax error because you cannot do:

MERGE INTO `table_ref`
AS (
WITH RECURSIVE ...
)

dbt does not have this problem because incremental models run in two stages, insert into _tmp and then merged so the recursive statement only exists with the CREATE OR REPLACE DDL rather than in the MERGE.

I can't see a way around this apart from not running the extra merge statement if WITH RECURSIVE is present in the SQL. You will lose some dry run safety but I think this is ok.