Struct ExpireSnapshotsAction 

pub struct ExpireSnapshotsAction { /* private fields */ }

A transaction action that removes snapshots from table metadata.

This only rewrites metadata; the now-unreferenced data and metadata files are left untouched. Physical file cleanup is the responsibility of a higher-level maintenance operation built on top of this action.

Selection follows Java RemoveSnapshots:

• Explicit ids (expire_snapshot_ids) and age-based expiry are combined: a snapshot is expired if it is named explicitly or selected by age.
• Age-based expiry always runs. The cutoff is expire_older_than_ms when set, a per-branch max_snapshot_age_ms for that branch, otherwise now - history.expire.max-snapshot-age-ms (default 5 days), matching Java’s constructor default.
• Expiry is computed per branch along each branch’s ancestry: each branch keeps its most recent retain_last snapshots — defaulting to history.expire.min-snapshots-to-keep, with a per-ref min_snapshots_to_keep overriding both — plus any ancestor newer than the cutoff, so a shared ancestor reachable from a retained branch is never expired.
• Refs are aged out first: a non-main branch or tag whose head is older than its max_ref_age_ms (defaulting to history.expire.max-ref-age-ms) is removed, and snapshots only that ref retained then become expirable.
• Heads of retained refs (including the current snapshot) are never expired, and naming one explicitly is an error, since remove_snapshots would otherwise drop the ref silently.

Implementations

impl ExpireSnapshotsAction

pub fn expire_snapshot_ids( self, snapshot_ids: impl IntoIterator<Item = i64>, ) -> Self

Expire these snapshot ids in addition to any age-based selection.

Age-based expiry runs by default (see the type-level docs), so a call that only names ids still expires snapshots older than history.expire.max-snapshot-age-ms. Pin expire_older_than_ms to a very old timestamp to expire by id alone.

Ids accumulate across calls (like add_data_files). An id that is still referenced by a branch or tag cannot be expired and causes commits to fail.

pub fn expire_older_than_ms(self, older_than_ms: i64) -> Self

Expire snapshots whose timestamp is strictly older than older_than_ms.

pub fn retain_last(self, retain_last: usize) -> Self

Keep at least the retain_last most recent snapshots of each branch when expiring by age (defaults to the table’s history.expire.min-snapshots-to-keep, must be at least 1).

This only bounds the age cutoff; it does not protect snapshots named via expire_snapshot_ids. Setting it to 0 makes commit fail.