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Brendan Clement
6367f7a0de
Five pages still said a refresh never revisits a filled row and that a changed input needs the column dropped and declared again. Since lancedb#4161 a refresh also recomputes rows whose inputs changed, so the quickstart, the feature-engineering overview, Guarantees, and the SQL REFRESH and UPDATE pages now say that. Retry claims are qualified the same way. A local refresh commits the column once, and a deployment's job commits finished batches. A retry fills what is still empty or stale, but can recompute values that were already written (a refresh whose input record was not saved recomputes next time), so no page promises that a retry costs only the unfinished rows.
35 lines
1.1 KiB
Plaintext
35 lines
1.1 KiB
Plaintext
---
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title: "Update"
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sidebarTitle: "Update"
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description: "UPDATE ... SET ... WHERE — and why it does not recompute derived columns."
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icon: pen
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keywords: ["update", "sql"]
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---
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<Badge color="red">Enterprise</Badge> [SQL runs on a deployment.](/sql)
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```sql
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UPDATE documents SET title = upper(title) WHERE category = 'film'
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```
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Assignments take any expression the [dialect](/sql/functions) supports,
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including references to other columns of the same row. Without a `WHERE`
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clause every row is updated.
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<Warning>
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An update does not recompute [computed columns](/feature-engineering/add-computed-column)
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that derive from the column you changed. Those rows keep the value computed from
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the old input until the next refresh recomputes them -- see
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[Guarantees](/basics/guarantees#jobs).
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</Warning>
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Commits a new table version, so [versioning](/management/table#versioning) and
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the [write guarantees](/basics/guarantees#writes) apply -- including that the
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version advances even when the statement affects zero rows.
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## What to read next {#next}
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<Card title="Update" icon="pen" href="/ingestion/update">
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The SDK equivalent.
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</Card>
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