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Brendan Clement
4f7dc90664
Cleanup keeps the files a branch still reads, and the version the branch was forked from only while the branch's remaining versions read the parent's files. Once the branch has replaced the data it inherited and its own older versions are pruned, cleanup removes the fork version like any other, so the cleanup and guarantees pages no longer list it among the versions cleanup always keeps. Both point readers who need an old version recoverable to a tag, under the tag policy the pages already describe, or a wide enough window.
120 lines
4.6 KiB
Plaintext
120 lines
4.6 KiB
Plaintext
---
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title: "Cleanup"
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sidebarTitle: "Cleanup"
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description: "Pruning old versions and the files only they referenced."
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icon: broom
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keywords: ["cleanup", "retention", "prune", "delete_unverified", "vacuum"]
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availability:
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oss: available
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enterprise: varies
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summary: >-
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In the embedded library, `optimize()` removes versions older than a
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retention window, 7 days by default. A deployment removes old versions in
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the background only when its configuration enables cleanup, and that
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configuration sets the retention period; `optimize()` is not available
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there.
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---
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Every write keeps the version before it, which is what makes
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[time travel](/management/table#versioning) possible. Cleanup is what ends
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that -- pruning versions older than a retention window, and the files that only
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those versions referenced.
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<Note>
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**Enterprise job type:** `cleanup`. Distinct from `compact` -- compaction
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merges files, cleanup removes them. `optimize()` in OSS runs both in one call;
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Enterprise schedules them as separate jobs, and runs cleanup only when the
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deployment's configuration enables it.
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</Note>
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## Retention {#retention}
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```python
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from datetime import timedelta
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table.optimize(cleanup_older_than=timedelta(days=30))
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```
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`cleanup_older_than` defaults to **7 days**. Versions older than that are
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removed, along with the files only they referenced. On a deployment, the
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retention period comes from its configuration instead.
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The latest version is never removed, whatever you pass. `timedelta(0)` makes
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every older version eligible for removal, but cleanup still keeps tagged
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versions and the files branches still read, as the warning below describes.
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<Warning>
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Pruning is what makes [time travel](/management/table#versioning) finite: an
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eligible version outside the retention window is gone. Cleanup keeps a version,
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whatever its age, when it is:
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- the **latest** version;
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- a **tagged** version.
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Cleanup also keeps the files a **branch** still reads, and the version the
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branch was forked from while the branch's remaining versions read the parent's
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files. That does not keep the fork for good: once the branch has replaced the
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data it inherited and its own older versions are pruned, cleanup prunes the
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fork version like any other. To keep a version recoverable, tag it, subject to
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the policy below, or keep the window wide enough to cover it.
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Under the default policy, a tag can also stop cleanup. When a tagged version is
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older than the window and is not the latest, cleanup refuses to run: it raises
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an error naming the tag and prunes nothing. To let it proceed, move the tag to a
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version inside the window, delete the tag, or widen the window.
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A tag on the latest version does not stop cleanup. But `optimize()` compacts
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before it prunes, and compacting commits a new version whenever it merges
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files, so a tag on what was the latest version can become an older one by the
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time cleanup runs. `optimize()` then raises after compacting, and its index
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update does not run.
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A deployment's background cleanup follows the same rules. If you rely on
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reading old versions, set the window to cover the range you need before
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running this, not after.
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</Warning>
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## Disk usage does not drop immediately {#disk}
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Compaction writes new, merged files before the old ones are removed, so disk
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usage can rise before it falls. Space is reclaimed only when cleanup prunes the
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versions that referenced the superseded files.
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If you need to reclaim space aggressively in the embedded library, shorten the
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retention window rather than waiting for the default:
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```python
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table.optimize(cleanup_older_than=timedelta(days=1))
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```
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## Files from failed transactions {#unverified}
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A write that fails partway can leave files that look like an operation still
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in progress. Cleanup will not remove them until they are at least seven days
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old, because it cannot tell them apart from a live write.
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```python
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table.optimize(delete_unverified=True)
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```
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This option belongs to `optimize()` in the embedded library. A deployment's
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cleanup jobs never set it.
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<Warning>
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`delete_unverified=True` removes them regardless of age. Only set it when you
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can guarantee **no other process is writing to the table** -- otherwise it can
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delete files belonging to a write that is genuinely in progress, and corrupt
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the table.
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</Warning>
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## What to read next {#next}
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<CardGroup cols={2}>
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<Card title="Compaction" icon="broom" href="/maintenance/compaction">
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Merging small files -- the other half of `optimize()`.
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</Card>
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<Card title="Background jobs" icon="gears" href="/maintenance/background-jobs">
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The Enterprise jobs that run without a call from you.
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</Card>
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</CardGroup>
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