Function plan_truncate_stmt 

pub fn plan_truncate_stmt(
    stmt: &Statement,
    catalog: &dyn SqlCatalog,
) -> Result<Vec<SqlPlan>>

Plan a TRUNCATE statement.

Each named collection resolves through the catalog: a vector-primary collection lowers to SqlPlan::VectorPrimaryTruncate, every other engine routes through its EngineRules::plan_truncate.