mirror of
https://github.com/lancedb/lancedb.git
synced 2026-11-13 22:26:53 +00:00
Brendan Clement
1db0d3ca5f
Labels early access features and hides features we aren't documenting yet. **Early access label:** Functions (4 pages, plus the GPU refresh, checkpointing and adaptive execution pages), Secrets (3 pages), Tiered Index Cache, Blob V2, and merge insert, which is labelled for Enterprise only. Two sidebar titles are shorter so the tag fits. **Hidden:** branching, JSON columns and geospatial. - The JSON functions page and the agent branch-experiments tutorial go in `.mintignore`. - `tables/branching` stays reachable but out of the nav, as #4859 left it, because SDK error messages link to it. - Other pages' mentions of these features become draft comments, so they're easy to restore. **Secrets page:** drops references to manual KMS setup, which the control plane handles. It keeps the encryption-at-rest facts, states the Azure value-size limit inline, and points a 501 error to support.
62 lines
2.5 KiB
Plaintext
62 lines
2.5 KiB
Plaintext
---
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title: "Functions"
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sidebarTitle: "Functions"
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description: "Where to find each kind of function, and the dialect version they come from."
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icon: function
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keywords: ["functions", "datafusion", "scalar", "aggregate", "window", "fts", "table function"]
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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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LanceDB executes SQL with [Apache DataFusion](https://datafusion.apache.org),
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currently **version 54**. The function set is DataFusion's default registration
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plus what Lance adds.
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| --- | --- |
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| [Scalar functions](/sql/dql/scalar-functions) | per row: math, string, regex, date/time, array, struct{/* Draft until JSON columns reach early access: restore ", JSON" */} |
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| [Aggregate functions](/sql/dql/aggregation#functions) | per group: `count`, `sum`, statistical, approximate |
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| [Window functions](/sql/dql/window#functions) | per window: ranking, offset, running aggregates |
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| [Table functions](#table-functions) | produce a relation rather than a value |
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<Note>
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Function availability is version-specific. DataFusion adds functions in most
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releases, so one documented on `main` may not exist in 54. When a name is not
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recognised, check it against the reference for that version before assuming a
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bug.
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</Note>
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## Table functions {#table-functions}
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A table function appears in `FROM` and produces a relation, which is what lets
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it return columns a scalar function has nowhere to put. Each has its own
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reference page:
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| --- | --- |
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| [`fts(table, query)`](/sql/dql/fts) | full-text search, with a relevance score alongside the matching rows |
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| [`dedupe(table, column, ...)`](/sql/dql/dedupe) | one representative row per near-duplicate group |
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| [`duplicate_pairs(table, column, ...)`](/sql/dql/duplicate-pairs) | every close pair, before resolving into groups |
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| [`generate_series(start, stop)`](/sql/dql/generate-series) | rows from a range |
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`_score`, the relevance pseudo-column `fts()` produces, is not a function;
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see [Data types](/sql/data-types#pseudo-columns).
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## What Lance accelerates {#accelerated}
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`contains_tokens` uses an index rather than scanning, which is the difference
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between a fast predicate and a slow one:
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| | Index used |
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| --- | --- |
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| [`contains_tokens`](/sql/dql/contains-tokens) | full-text index |
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{/*
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Draft until JSON columns reach early access; restore "Two function families" above.
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| [`json_get`, typed variants, `json_extract`](/sql/dql/json-functions) | JSON scalar index |
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*/}
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Confirm with [`EXPLAIN`](/sql/dql/explain): an accelerated predicate shows an
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index node rather than a `LanceScan` followed by a filter.
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