# `StatifierPersistence.Migration`
[🔗](https://github.com/riddler/statifier_persistence/blob/v0.18.0/lib/statifier_persistence/migration.ex#L1)

Moving a waiting execution from one chart onto another, on purpose.

An execution is pinned to the chart it started on: its stored row carries
that chart's content hash, and the identity guard refuses to load its
position against any other machine. A migration is the explicit act that
re-pins it. It is decided in this package's ADR-0013
(`docs/adr/0013-the-migration-plan.md`): a plan is data, one plan per pair
of chart hashes; it is a transform over the engine's position export,
applied by the engine's import on the new machine; it is checked twice,
once against the two machines and once against the execution; and it
either re-pins the execution whole or leaves it as it was.

`StatifierPersistence.Migration.Plan` is the plan: its struct, its one
JSON-safe map encoding, and the static validation against the two
machines. `StatifierPersistence.Executions.migrate/4` applies a plan to
one execution. Nothing in this package migrates an execution because a
chart was saved, created against or published.

## Not the table migrations

This namespace is about executions, not tables.
`StatifierPersistence.Ecto.Migrations` is the schema-migration helper a
host runs to create and upgrade this package's tables; it moves no
execution between charts, and nothing here touches a table's shape.

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*Consult [api-reference.md](api-reference.md) for complete listing*