---
description: 'System table containing information about merges and part mutations
  currently in process for tables in the MergeTree family.'
keywords: ['system table', 'merges']
slug: /operations/system-tables/merges
title: 'system.merges'
---

import SystemTableCloud from '@site/docs/_snippets/_system_table_cloud.md';

# system.merges

<SystemTableCloud/>

Contains information about merges and part mutations currently in process for tables in the MergeTree family.

Columns:

- `database` (String) — The name of the database the table is in.
- `table` (String) — Table name.
- `elapsed` (Float64) — The time elapsed (in seconds) since the merge started.
- `progress` (Float64) — The percentage of completed work from 0 to 1.
- `num_parts` (UInt64) — The number of pieces to be merged.
- `result_part_name` (String) — The name of the part that will be formed as the result of merging.
- `is_mutation` (UInt8) — 1 if this process is a part mutation.
- `total_size_bytes_compressed` (UInt64) — The total size of the compressed data in the merged chunks.
- `total_size_marks` (UInt64) — The total number of marks in the merged parts.
- `bytes_read_uncompressed` (UInt64) — Number of bytes read, uncompressed.
- `rows_read` (UInt64) — Number of rows read.
- `bytes_written_uncompressed` (UInt64) — Number of bytes written, uncompressed.
- `rows_written` (UInt64) — Number of rows written.
- `memory_usage` (UInt64) — Memory consumption of the merge process.
- `thread_id` (UInt64) — Thread ID of the merge process.
- `merge_type` — The type of current merge. Empty if it's an mutation.
- `merge_algorithm` — The algorithm used in current merge. Empty if it's an mutation.
