---
layout: docu
redirect_from:
- /docs/preview/guides/troubleshooting/oom_errors
- /docs/stable/guides/troubleshooting/oom_errors
title: Out of Memory Errors
---

DuckDB has a state of the art out-of-core query engine that can spill to disk for larger-than-memory processing.
We continuously strive to improve DuckDB's scalability and prevent out of memory errors whenever possible.
That said, you may still experience out-of-memory errors if you run queries with multiple [blocking operators]({% link docs/current/guides/performance/how_to_tune_workloads.md %}#blocking-operators), certain aggregation functions, `PIVOT` operations, etc., or if you have very little available memory compared to the dataset size.

## Types of “Out of Memory” Errors

Out of memory errors mainly occur in two forms:

### `OutOfMemoryException`

Most of the time DuckDB runs out of memory with an `OutOfMemoryException`.
For example:

```console
duckdb.duckdb.OutOfMemoryException: Out of Memory Error: failed to pin block of size 256.0 KiB (476.7 MiB/476.8 MiB used)
```

### OOM Reaper (Linux)

Many Linux distributions have an [OOM killer or OOM reaper process](https://learn.redhat.com/t5/Platform-Linux/Out-of-Memory-Killer/td-p/48828)
whose goal is to prevent memory overcommitment.
If the OOM reaper killed your process, you often see the following message where DuckDB was running:

```console
Killed
```

To get more detailed information, check the diagnostic messages using the [`dmesg` command](https://en.wikipedia.org/wiki/Dmesg) (you may need `sudo`):

```batch
sudo dmesg
```

If the process was killed by the OOM killer/reaper, you will find an entry like this:

```console
[Fri Apr 18 02:04:10 2025] Out of memory: Killed process 54400 (duckdb) total-vm:1037911068kB, anon-rss:770031964kB, file-rss:0kB, shmem-rss:0kB, UID:1000 pgtables:1814612kB oom_score_adj:0
```

## Troubleshooting Out-of-Memory Errors

To prevent out-of-memory errors, please consult the [“Out-of-Memory” issues]({% link docs/current/guides/performance/oom.md %}) page of the Performance Guide.

## See Also

For more information on DuckDB's memory management, see the [“Memory Management in DuckDB” blog post]({% post_url 2024-07-09-memory-management %}).