Function route_partition_insert 

pub fn route_partition_insert(
    context: &PartitionContext<'_>,
    requested_table: &str,
    document: &ResultRow,
    params: &[SQLParam],
    include_descendants: bool,
) -> Result<PartitionRoute, SQLError>

Route a row that an INSERT writes through requested_table, as ExecFindPartition does: a partitioned table that is itself a partition first checks its own partition constraint, and each level then selects the partition whose bound accepts the row. A relation that is not partitioned stores the row itself, without a check: ExecInsert checks the partition constraint of a partition that the statement names after its other constraints, which the caller does with partition_constraint_accepts_row.