> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vortexiq.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Merges In Progress, ClickHouse

> Merges In Progress for ClickHouse deployments. Tracked live in Vortex IQ Nerve Centre. How to read it, why it matters, and how to act on it.

**Card class:** [Non-Hero](/nerve-centre/overview#card-classes-explained)  •  **Category:** [Ingest & Merges](/nerve-centre/connectors#connectors-by-type)

## At a glance

> **Merges In Progress** is the live count of background part merges ClickHouse is running right now, read from the `Merge` metric in `system.metrics`. A few concurrent merges is healthy housekeeping: ClickHouse is steadily combining the small parts created by inserts into larger, more efficient ones. A sustained high count is the warning sign that ingest is outpacing merge throughput, which is the road to a parts backlog and, eventually, a `Too Many Parts` halt.

## What it tracks

The card reports the value of the `Merge` metric from `system.metrics`, which is the number of background merge operations executing at the sample instant. Every `INSERT` into a MergeTree table writes a new data part; ClickHouse continually merges those parts in the background to keep part counts low and reads fast. The count rising and falling through the day is normal. The signal to watch for is a *sustained* high count: that means new parts are arriving faster than the merge scheduler can consolidate them, so the parts backlog grows. Left unchecked, the backlog drives up [Active Parts (Top 10 Tables)](/nerve-centre/kpi-cards/clickhouse/active-parts-top-10-tables) and can trip the `Too Many Parts` cap that halts ingest on the affected table. The card has no fixed alert threshold (`time_window` is `RT`); read it alongside active-parts and ingest-rate cards to judge whether the merge load is keeping up. The typical cause of a runaway count is too-frequent small inserts; batching inserts (fewer, larger `INSERT`s) is the standard fix.

## Reconciling against the source

Confirm the live count directly with `SELECT value FROM system.metrics WHERE metric = 'Merge'`, and see the actual running merges (table, progress, elapsed) with `SELECT table, elapsed, progress, rows_read, rows_written FROM system.merges`. On ClickHouse Cloud the same `system.merges` and `system.metrics` reads apply per node.

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### Tracked live in Vortex IQ Nerve Centre

*Merges In Progress* is one of hundreds of KPI pulses Vortex IQ tracks across ClickHouse and 70+ other ecommerce connectors. Nerve Centre runs the detection layer; Vortex Mind investigates the cause when something moves; Ask Viq lets you interrogate any number in plain English.

[Start for free](https://app.vortexiq.ai/login) or [book a demo](https://www.vortexiq.ai/contact-us) to see this metric running on your own data.