---
title: SQL Functions Overview
metaTitle: SQL Functions Reference | OpenObserve
description: "Reference for OpenObserve SQL functions by category: full-text search, secondary index, array, aggregate, and approximate aggregate."
---

# SQL Functions

This section provides documentation for all SQL functions supported in OpenObserve. Functions are grouped by category to help you quickly find the one that fits your use case.

## Function categories

- [Full-Text Search Functions](full-text-search.md)
- [Secondary Index Functions](secondary-index.md)
- [Array Functions](array.md)
- [Aggregate Functions](aggregate.md)
- [Approximate Aggregate Functions](approximate-aggregate/index.md)
    - [Approximate Aggregate Overview](approximate-aggregate/index.md)
    - [`approx_topk`](approximate-aggregate/approx-topk.md)
    - [`approx_topk_distinct`](approximate-aggregate/approx-topk-distinct.md)

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