feat(snowflake): transpile Snowflake IDENTIFIER function to DuckDB

[fivetran-kwoodbeck]

Snowflake's IDENTIFIER(), which resolves a string to a runtime identifier, previously fell through to exp.Anonymous. This folds it into a typed exp.Identifier node (flagged with identifier_func=True) so the Snowflake generator reconstructs IDENTIFIER('name') and the DuckDB generator emits a native identifier. It includes splitting dot-qualified names like IDENTIFIER('t1.col') into a proper exp.Dot chain.

Non-foldable args like IDENTIFIER($var) remain as exp.Anonymous so they round-trip correctly.

Behavior

Snowflake input	DuckDB output
IDENTIFIER('col')	col
IDENTIFIER('t1.col')	t1.col
IDENTIFIER('"Col"')	"Col"
IDENTIFIER($var)	IDENTIFIER($var)

[georgesittas]

Hey @fivetran-kwoodbeck, I don't think this is the right approach. We should parse the IDENTIFIER(...) argument, and only when it's a string, otherwise you risk breaking case-sensitive identifiers. I wonder if we should just use to_column and to_table directly and produce semantically equivalent SQL without the IDENTIFIER call.

Falling back to an Anonymous node in other cases is good. I would also have a try-except block to make sure we gracefully handle parse failures and fall back to the IDENTIFIER(...) syntax.

Check this out too: https://github.com/fivetran/sqlglot-integration-tests/pull/452#pullrequestreview-4467142494.

[georgesittas]

@fivetran-kwoodbeck this looks better. One comment is pending and I think the submodule pointer needs to be updated as well.

[fivetran-kwoodbeck]

@fivetran-kwoodbeck this looks better. One comment is pending and I think the submodule pointer needs to be updated as well.

@georgesittas I replied and updated the submodule