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Jack Ye
ddb318567a
## Summary - Complete the SQL reference: `ATTACH DATABASE`, the `CHANGES` clause, and `dedupe()`/`duplicate_pairs()` (verified against current sophon source; these were recently renamed from `vector_dedup`/`vector_duplicate_pairs`). Fix the blob-column default-projection claim and add the previously undocumented `blob_descriptor()`. - Enrich the gated Functions draft (still `.mintignore`'d, pre-release): chained Functions over blob outputs, GPU-produced blobs, Secrets, multi-input/output binding, `code=[module]` packaging. - Upgrade the materialized-view and computed-column auto-refresh drafts with precise, verified catch-up semantics, and add the missing `ALTER MATERIALIZED VIEW` / `CREATE ... WITH(...)` sections (also gated — the automatic-refresh scheduler is still dev/staging-only). - Thread one running example (video frames → GPU extract/caption → dedup → auto-refreshing materialized view) through Functions, materialized views, and the LeRobotDataset integration guide instead of a separate tutorial. - Rename "LanceDB OSS"/"OSS" to "LanceDB Embedded"/"Embedded" throughout (52 files); activate the existing availability-comparison mechanism on `basics/offerings.mdx` for a full feature-by-feature comparison table.
124 lines
4.4 KiB
Plaintext
124 lines
4.4 KiB
Plaintext
---
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title: "Materialized View"
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sidebarTitle: "Materialized View"
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description: "CREATE MATERIALIZED VIEW and SHOW MATERIALIZED VIEWS; refreshing is a REFRESH statement."
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icon: table
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keywords: ["materialized view", "create materialized view", "show materialized views", "sql"]
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availability:
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embedded: unavailable
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enterprise: available
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---
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A materialized view stores a query's result as rows, kept current by a refresh.
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It is the counterpart to a [view](/sql/ddl/view), which stores only the query.
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<Note>
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Materialized views are off by default in LanceDB Enterprise and have to be enabled
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there. Which statements and query shapes a deployment accepts, whether it needs
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the source table to have stable row ids, and how it refreshes a view depend on
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its LanceDB Enterprise version and configuration.
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</Note>
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## CREATE MATERIALIZED VIEW {#create}
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```sql
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CREATE MATERIALIZED VIEW <name> AS SELECT ...
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```
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Once created, a materialized view can be queried like a table. Use the
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statements below to list, refresh and drop it. For SDK methods, see
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[Materialized views](/management/materialized-view#create).
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{/*
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Draft for automatic materialized-view refresh. Enable this section, and
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"ALTER MATERIALIZED VIEW" below, when the server feature is released.
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Set scheduling options at creation, continuing the join and chained
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Functions from [Functions](/management/function#chain):
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```sql
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CREATE MATERIALIZED VIEW frames_captioned AS
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SELECT f.frame_id, extract_frame(v.video, f.ts) AS jpeg,
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caption(extract_frame(v.video, f.ts)) AS caption
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FROM videos v JOIN frames f ON v.id = f.video_id
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WHERE f.selected = true
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WITH (auto_refresh_enabled = false, auto_refresh_interval_seconds = 5)
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```
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`auto_refresh_enabled` and `auto_refresh_interval_seconds` work the same way
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here as for a [computed column](/sql/ddl/table#automatic-refresh-options):
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the interval is a minimum pacing after the last successful refresh, and
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automatic execution needs the same server-side switch enabled. Omitting
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`WITH` leaves automatic refresh at the server's default.
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*/}
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## SHOW MATERIALIZED VIEWS {#show}
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```sql
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SHOW MATERIALIZED VIEWS
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```
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<Note>
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This asks the server for its views, as the SDK's `list_materialized_views` does
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on a `db://` connection.
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</Note>
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## Refreshing one {#refresh}
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```sql
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REFRESH MATERIALIZED VIEW chunks
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```
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See [REFRESH MATERIALIZED VIEW](/sql/dml/refresh-materialized-view) for the full syntax,
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and compatibility notes for older server versions.
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{/*
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Draft for automatic materialized-view refresh. Enable this section when the
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server feature is released; see the note on "CREATE MATERIALIZED VIEW" above.
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## ALTER MATERIALIZED VIEW {#alter}
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```sql
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ALTER MATERIALIZED VIEW frames_captioned SET auto_refresh_enabled = true;
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ALTER MATERIALIZED VIEW frames_captioned SET auto_refresh_interval_seconds = 300;
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ALTER MATERIALIZED VIEW frames_captioned SET auto_refresh_enabled = false;
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```
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The whole view toggles together; there is no per-output granularity the way
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a multi-output Function column has one setting per output. SET takes effect
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immediately and does not itself run a refresh:
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- **Disabling** prevents new automatic refreshes. An inflight one may still
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finish, and `REFRESH MATERIALIZED VIEW` keeps working manually.
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- **Re-enabling catches up the entire backlog in one pass**, the same as a
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computed column's [automatic refresh](/sql/ddl/table#automatic-refresh-options):
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the next scheduler tick picks up every source change accumulated since the
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view was disabled, immediately, with no further write needed to trigger it.
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A materialized view's *initial* population, at `CREATE` or when the server
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runs it, happens regardless of `auto_refresh_enabled`; only refreshes after
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that are gated by the setting.
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*/}
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## Dropping one {#drop}
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A materialized view **is** a table, so it is dropped with
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[`DROP TABLE`](/sql/ddl/table#drop). For the same reason, dropping one removes
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stored rows, unlike dropping a [view](/sql/ddl/view#drop).
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<Note>
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**Enterprise job type for a refresh:** `sql`. Dropping, by contrast, runs the
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same job as dropping any table, `drop_table` or `drop_object`.
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</Note>
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## What to read next {#next}
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<CardGroup cols={2}>
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<Card title="Materialized View" icon="table" href="/management/materialized-view">
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Creating one from the SDK.
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</Card>
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<Card title="Refresh a materialized view" icon="arrows-rotate" href="/feature-engineering/refresh-materialized-view">
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How a refresh works, in LanceDB Enterprise.
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</Card>
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</CardGroup>
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