Enum SchemaMigrationStep 

pub enum SchemaMigrationStep {
    AddPredicate {
        name: String,
        arity: usize,
    },
    RemovePredicate {
        name: String,
    },
    RenamePredicate {
        old_name: String,
        new_name: String,
    },
    AddArityColumn {
        predicate: String,
        position: usize,
        default_value: String,
    },
    RemoveArityColumn {
        predicate: String,
        position: usize,
    },
    AddDomain {
        name: String,
    },
    RemoveDomain {
        name: String,
    },
    AddRule {
        name: String,
    },
    RemoveRule {
        name: String,
    },
}

A concrete migration step to transform the old schema into the new schema.

Variants

AddPredicate

Create a new predicate slot.

Fields

name: String

arity: usize

RemovePredicate

Drop an existing predicate slot.

Fields

name: String

RenamePredicate

Rename a predicate (non-destructive when reverse is possible).

Fields

old_name: String

new_name: String

AddArityColumn

Extend a predicate by inserting a new positional argument.

Fields

predicate: String

position: usize

default_value: String

RemoveArityColumn

Shrink a predicate by removing a positional argument.

Fields

predicate: String

position: usize

AddDomain

Register a new domain.

Fields

name: String

RemoveDomain

Unregister an existing domain.

Fields

name: String

AddRule

Bind a new variable/rule entry.

Fields

name: String

RemoveRule

Remove an existing variable/rule entry.

Fields

name: String

Implementations

impl SchemaMigrationStep

pub fn description(&self) -> String

Human-readable description of the step.

pub fn is_destructive(&self) -> bool

Returns true when this step is destructive (data may be lost).

Trait Implementations

impl Clone for SchemaMigrationStep

fn clone(&self) -> SchemaMigrationStep

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SchemaMigrationStep

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

Formats the value using the given formatter.