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Brendan Clement
6398ff3629
Databases, namespaces, jobs and data evolution work in both offerings. Materialized views, computed columns and column refresh work in the embedded library and vary on a deployment, which has to enable them. Views and functions exist only on a deployment that enables them, and aggregation, joins, windowing and sampling are SQL, so they need one with SQL enabled. Sections now say where they differ: views have SDK methods on a deployment, dropping a function needs a further setting, a local job handle runs in-process and has no history, create_index and refresh_column behave differently against a deployment, and the overviews no longer call computed columns and materialized views available everywhere.
35 lines
1.3 KiB
Plaintext
35 lines
1.3 KiB
Plaintext
---
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title: "Views"
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sidebarTitle: "View"
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description: "A saved query, evaluated when read. The non-materialized counterpart to a materialized view."
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icon: eye
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keywords: ["view", "create view", "sql", "catalog"]
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availability:
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oss: unavailable
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enterprise: varies
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summary: >-
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Views need a LanceDB Enterprise deployment that has them enabled; the
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embedded library cannot create them.
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---
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A view stores a **query**, not rows. Reading it runs the query against current
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data, so a view is never stale -- and never faster than the query it wraps.
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It is the counterpart to a
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[materialized view](/management/materialized-view), which stores rows and is
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brought up to date by a refresh. Both are [catalog objects](/basics/catalog)
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defined by a query; the difference is entirely when that query runs.
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| | View | Materialized view |
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| --- | --- | --- |
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| Stores | the query | the rows |
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| Freshness | always current | as of the last refresh |
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| Read cost | the full query, every read | a table scan |
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| Write cost | none | a refresh |
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Views are created on a deployment, either in SQL over the
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[Flight SQL endpoint](/sql#connecting) or with the SDKs' `create_view` /
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`createView`, which send the query to the deployment. Either way, the deployment
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must have views enabled. See [View](/sql/ddl/view) for `CREATE VIEW`,
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`DROP VIEW`, and listing.
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