lancedb/docs/web/sql/scalar-functions.mdx

---
title: "Scalar functions"
sidebarTitle: "Scalar Functions"
description: "The per-row function set: math, string, regex, date/time, array, struct, and what Lance adds."
icon: calculator
keywords: ["scalar functions", "string functions", "math functions", "regex", "array functions", "json"]
---

<Badge color="red">Enterprise</Badge> [SQL runs on a deployment.](/sql)

Functions that take a value and return a value, one row at a time. The set is
based on DataFusion's registration plus Lance and deployment-specific
functions. The names below are selected examples, not an exhaustive catalog
for every deployment. Availability depends on the deployed version and build.

For per-group functions see [Aggregation](/sql/dql/aggregation); for per-window,
[Window functions](/sql/dql/window).

## Math {#math}

```text
abs  ceil  floor  round  trunc  signum  power  sqrt  cbrt  exp
ln  log  log2  log10  factorial  gcd  lcm  pi  random  nanvl
isnan  iszero  cot  degrees  radians  to_degrees  to_radians
sin  cos  tan  asin  acos  atan  atan2
sinh  cosh  tanh  asinh  acosh  atanh
```

## String {#string}

```text
ascii  bit_length  btrim  chr  concat  concat_ws  contains  ends_with
starts_with  levenshtein  lower  upper  ltrim  rtrim  octet_length
repeat  replace  split_part  to_hex  uuid
```

Unicode-aware variants:

```text
character_length  find_in_set  initcap  left  right  lpad  rpad
reverse  strpos  substr  substr_index  substring  translate
```

<Note>
For keyword matching on a text column, [`contains_tokens`](#contains-tokens) is
index-accelerated where `contains` and `LIKE` are not.
</Note>

## Regular expressions {#regex}

```text
regexp_count  regexp_instr  regexp_like  regexp_match  regexp_replace
```

## Date and time {#datetime}

```text
current_date  current_time  date_bin  date_part  date_trunc
from_unixtime  to_unixtime  make_date  make_time  to_char
to_date  to_time  to_local_time
```

`date_bin` is the one worth knowing for analytics: it buckets timestamps into
fixed-width intervals, which is how you build a time series without a
self-join.

```sql
SELECT date_bin(INTERVAL '1 hour', created_at) AS hour, count(*)
FROM events GROUP BY hour ORDER BY hour
```

## Arrays and maps {#arrays}

```text
make_array  array_has  array_filter  array_transform  array_any_match
array_compact  array_normalize  array_slice  arrays_zip  cardinality
flatten  range  generate_series
```

```text
map  map_keys  map_values  map_entries  map_extract
```

Distance functions over arrays:

```text
cosine_distance  distance  exact_distance  inner_product
```

<Warning>
Distance functions can evaluate arrays per row. Some deployment versions also
recognize `ORDER BY distance(vector, query_vector) LIMIT k` over a table scan
and plan it as vector search, with indexed or flat search as appropriate.
Where available, `exact_distance` evaluates distance without that rewrite.
Confirm the
functions supported by your deployment and inspect SQL
[`EXPLAIN`](/sql/dql/explain); the function name alone does not guarantee an
index-backed plan. See [SQL vector search](/basics/sql#no-vector-sql).
</Warning>

## Structs and fields {#structs}

```text
named_struct  get_field  coalesce  nullif  nvl  nvl2  greatest  least
union_extract  union_tag
```

## Crypto and encoding {#crypto}

```text
digest  md5  sha224  sha256  sha384  sha512  encode  decode
```

## Type functions {#type}

```text
arrow_cast  arrow_try_cast  arrow_typeof  arrow_field  arrow_metadata
with_metadata  version
```

`arrow_typeof` is the fastest way to answer "what is this column, really" when a
result does not have the shape you expected:

```sql
SELECT arrow_typeof(vector) FROM documents LIMIT 1
-- FixedSizeList(Field { name: "item", data_type: Float32, .. }, 1536)
```

`arrow_cast` casts to an Arrow type by name, reaching types SQL has no spelling
for. See [Data types](/sql/data-types).

## What Lance adds {#lance}

These are registered by Lance on top of DataFusion's set.

### `contains_tokens(column, tokens)` {#contains-tokens}

```sql
SELECT * FROM my_docs WHERE contains_tokens(text, 'fox jumps dog')
```

True when the column contains **all** the tokens, split on whitespace and
punctuation. Equivalent to an `fts()` match query with fuzziness off, `AND`
semantics and the simple tokenizer.

**Index-accelerated.** When the column has a full-text index that suits the
query, the planner uses it instead of scanning — which is the reason to prefer
it over `LIKE` for keyword tests.

### JSON accessors {#json}

| Function | Returns |
| --- | --- |
| `json_get(col, key)` | the value at `key`, still JSON |
| `json_get_string(col, key)` | `Utf8` |
| `json_get_int(col, key)` | `Int64` |
| `json_get_float(col, key)` | `Float64` |
| `json_get_bool(col, key)` | `Boolean` |
| `json_extract(col, path)` | `Utf8`, by path |
| `json_extract_with_type(col, path, type)` | the requested type |
| `json_exists(col, path)` | `Boolean` |
| `json_array_contains(col, value)` | `Boolean` |
| `json_array_length(col)` | length |

`json_get` returns JSON, so accessors nest:

```sql
SELECT * FROM events
WHERE json_get_string(json_get(json_get(data, 'user'), 'profile'), 'name') = 'Alice'
```

**`json_get`, its typed variants, and `json_extract` are index-accelerated** by a
JSON scalar index on the column. The rest evaluate per row.

### Geospatial {#geo}

<Warning>
Lance defines `st_*` functions on GeoArrow, but they sit behind a build feature
**LanceDB does not ship**. Calling one returns an error naming the missing
feature rather than an unknown-function error, and the spatial index is gated
the same way.
</Warning>

## Reaching a function not listed here {#escape-hatch}

Nothing wraps or restricts the set — a query reaches any registered function by
writing it. When a name is not recognised, check it against
[DataFusion's scalar function reference](https://datafusion.apache.org/user-guide/sql/scalar_functions.html)
for version 54 before assuming it is unsupported; functions are added in most
DataFusion releases, and a function documented on `main` may not exist here yet.