Enum UnpreservedReason 

#[non_exhaustive]
pub enum UnpreservedReason {
    NonPortableDefault,
    UnsupportedConstraint,
}

Why a piece of the source schema could not be reproduced.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

NonPortableDefault

The column’s DEFAULT expression is not portable to another database.

Hyper stores non-literal defaults fully qualified by the database that contains the table: NOW() comes back out of pg_attrdef.adsrc as "mydb"."pg_catalog"."now"(), and DATE '2020-01-01' as "mydb"."pg_catalog"."date" '2020-01-01'. Re-emitting that text into a different database is accepted by the engine but stores a reference to "mydb" — a database that will not be attached when the copy is opened on its own later. Dropping the default is the lesser evil, so long as it is reported.

UnsupportedConstraint

A constraint the destination CREATE TABLE cannot restate.

A Hyper-written table only ever holds the assumed key forms, which are reproduced exactly. This covers what a .hyper from an engine with index support could contain — an enforced PRIMARY KEY or UNIQUE, a CHECK, a foreign key — where restating it as ASSUMED would downgrade an enforced constraint to an unenforced one and call it preserved.

Trait Implementations

impl Clone for UnpreservedReason

fn clone(&self) -> UnpreservedReason

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for UnpreservedReason

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for UnpreservedReason

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for UnpreservedReason

impl PartialEq for UnpreservedReason

fn eq(&self, other: &UnpreservedReason) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for UnpreservedReason