---
title: merge_chunks_concurrently() | Tiger Data Docs
description: Merge two or more chunks into one chunk without blocking reads
---

Since [2.18.0](https://github.com/timescale/timescaledb/releases/tag/2.18.0)

Merge two or more chunks into one in concurrent mode without locking out other reads. The functionality is equivalent to `merge_chunks()` with the `concurrently` option set, although this procedure works with more than two chunks. See [`merge_chunks()`](/docs/reference/timescaledb/hypertables/merge_chunks/index.md) for more information.

## Samples

- **Merge three chunks, allowing concurrent reads**:

  ```
  CALL merge_chunks_concurrently('_timescaledb_internal._hyper_1_1_chunk', '_timescaledb_internal._hyper_1_2_chunk', '_timescaledb_internal._hyper_1_3_chunk');
  ```

## Arguments

You can merge either two chunks, or an arbitrary number of chunks specified as an array of chunk identifiers.

| Name     | Type        | Default | Required | Description                                     |
| -------- | ----------- | ------- | -------- | ----------------------------------------------- |
| `chunks` | REGCLASS\[] | -       | ✖        | The array of chunks to merge in partition order |

## Returns

This procedure does not return a value. Upon successful completion, the specified chunks are merged into a single chunk.