mirror of
https://github.com/lancedb/lancedb.git
synced 2026-10-20 10:42:26 +00:00
Brendan Clement
198812fd53
The existing docs have 254 findings from our shared Vale rules. Contributors would otherwise inherit these when editing the same lines. Clean up the prose across 80 pages: correct product names and a repeated word, simplify a few phrases, and replace dashes with punctuation that fits each sentence. The pinned Vale scan now reports zero findings, with no suppressions.
101 lines
3.1 KiB
Plaintext
101 lines
3.1 KiB
Plaintext
---
|
|
title: "REFRESH"
|
|
sidebarTitle: "REFRESH"
|
|
description: "Filling computed columns and bringing materialized views up to date."
|
|
icon: arrows-rotate
|
|
keywords: ["refresh column", "refresh materialized view", "backfill", "cascade"]
|
|
---
|
|
|
|
<Badge color="red">Enterprise</Badge> [SQL runs in LanceDB Enterprise.](/sql)
|
|
|
|
LanceDB extensions with no DataFusion equivalent. They are what makes
|
|
[feature engineering](/feature-engineering) reachable from SQL: a column
|
|
declared by [DDL](/sql/ddl/table#computed-column) starts empty, and a refresh fills it.
|
|
|
|
## REFRESH COLUMN {#refresh-column}
|
|
|
|
```sql
|
|
REFRESH COLUMN <column> ON [TABLE] <table>
|
|
[WHERE <predicate>]
|
|
[WITH (<option> = <value> [, ...])]
|
|
```
|
|
|
|
```sql
|
|
REFRESH COLUMN doubled ON my_table
|
|
REFRESH COLUMN embedding ON documents WHERE created_at > '2026-01-01'
|
|
```
|
|
|
|
A refresh gives values to rows that lack them, recomputes rows whose inputs
|
|
changed, and **leaves other filled rows alone**. That makes it idempotent, cheap
|
|
to repeat as data arrives, and safe to re-run after a failure, though a re-run
|
|
can recompute values the failed run had already written.
|
|
|
|
`WHERE` scopes the refresh, which is how you fill a slice and check it before
|
|
committing to the whole table.
|
|
|
|
### Options {#refresh-column-options}
|
|
|
|
| Option | Meaning |
|
|
| --- | --- |
|
|
| `num_workers` | how many workers to use |
|
|
| `cpu_millis` | CPU budget per worker |
|
|
| `memory_bytes` | memory budget per worker |
|
|
| `gpu_count` | GPUs per worker |
|
|
| `batch_size` | rows a worker takes at a time |
|
|
| `error_policy` | `'skip'` continues past failing rows instead of failing the job |
|
|
|
|
```sql
|
|
REFRESH COLUMN embedding ON documents
|
|
WITH (cpu_millis = 8000, memory_bytes = 17179869184, gpu_count = 2)
|
|
```
|
|
|
|
`num_workers` sets a count; the budget options size each worker. They are
|
|
alternatives rather than a pair.
|
|
|
|
{/*
|
|
Draft for the Functions release.
|
|
|
|
<Note>
|
|
`error_policy` and `num_workers` are refused for a column filled by a registered
|
|
[function](/management/function) with its own resource budget -- use the CPU,
|
|
memory and GPU options there.
|
|
</Note>
|
|
*/}
|
|
|
|
## REFRESH MATERIALIZED VIEW {#refresh-materialized-view}
|
|
|
|
```sql
|
|
REFRESH MATERIALIZED VIEW <name>
|
|
```
|
|
|
|
```sql
|
|
REFRESH MATERIALIZED VIEW chunks
|
|
```
|
|
|
|
A refresh updates the view's stored result. Refresh views in dependency order,
|
|
starting with their source views.
|
|
|
|
<Note>
|
|
Some older server versions accepted `WITH (full = true)` and `CASCADE`.
|
|
Those options are not accepted by the SQL implementation described here.
|
|
Use the basic statement above; do not assume that the options accepted by a
|
|
local SDK's `refresh()` method are also SQL options.
|
|
</Note>
|
|
|
|
## Watching a refresh {#watching}
|
|
|
|
Both statements submit work that outlives the call. Track it with
|
|
[`SHOW JOBS`](/sql/ddl/job#show), and diagnose failures with
|
|
[`SHOW ERRORS`](/sql/ddl/job#errors).
|
|
|
|
## See also {#see-also}
|
|
|
|
<CardGroup cols={2}>
|
|
<Card title="Refresh a column" icon="arrows-rotate" href="/feature-engineering/refresh-column">
|
|
The same operation from the SDKs, and what a refresh guarantees.
|
|
</Card>
|
|
<Card title="Table" icon="table" href="/sql/ddl/table#alter">
|
|
Declaring the columns this fills.
|
|
</Card>
|
|
</CardGroup>
|