# GCP deployment guidelines
General guidelines when deploying Self-Managed Materialize on GCP.
## Recommended instance types

As a general guideline, we recommend:

- ARM-based CPU.
- A 1:8 ratio of vCPU to GiB memory.
- At least a 2:1 ratio of GiB local instance storage to GiB memory when using swap.

When operating on GCP in production, we recommend the Arm-based [C4A
high-memory series]. Both C4A and C4 offer local SSDs only on their `-lssd`
machine variants, which bundle a fixed number of Titanium SSD disks.

| Series | Examples   |
| ------ | ---------- |
| [C4A high-memory series] (recommended) | `c4a-highmem-16-lssd` or `c4a-highmem-32-lssd` |
| [C4 high-memory series] | `c4-highmem-16-lssd` or `c4-highmem-32-lssd` |

C4A is not available in every region. Where it is unavailable, use the
x86-based [C4 high-memory series] instead.

To maintain the recommended disk-to-RAM ratio for your machine type, see
[Number of local SSDs](#number-of-local-ssds) to determine the number of local
SSDs to use.

See also [Locally attached NVMe storage](#locally-attached-nvme-storage).

## Number of local SSDs

Each local SSD in GCP provides 375GB of storage. Use the appropriate number
of local SSDs to ensure your total disk space is at least twice the amount of RAM in your
machine type for optimal Materialize performance.

C4A and C4 bundle a fixed number of Titanium SSD disks in each `-lssd`
machine variant. The count is not configurable, but every high-memory `-lssd`
variant satisfies the 2:1 disk-to-RAM ratio:

| Machine Type          | RAM     | Bundled Local SSDs | Total SSD Storage |
|-----------------------|---------|--------------------|-------------------|
| `c4a-highmem-8-lssd`  | `64GB`  | 2                  | `750GB`           |
| `c4a-highmem-16-lssd` | `128GB` | 4                  | `1500GB`          |
| `c4a-highmem-32-lssd` | `256GB` | 6                  | `2250GB`          |
| `c4a-highmem-64-lssd` | `512GB` | 14                 | `5250GB`          |
| `c4-highmem-8-lssd`   | `62GB`  | 1                  | `375GB`           |
| `c4-highmem-16-lssd`  | `124GB` | 2                  | `750GB`           |
| `c4-highmem-32-lssd`  | `248GB` | 5                  | `1875GB`          |
| `c4-highmem-48-lssd`  | `372GB` | 8                  | `3000GB`          |

For other machine series, the local SSD count is configurable but may only
support predefined values. To determine the valid number of local SSDs to
attach for your machine type, see the [GCP
documentation](https://cloud.google.com/compute/docs/disks/local-ssd#lssd_disk_options).

[C4A high-memory series]: https://cloud.google.com/compute/docs/general-purpose-machines#c4a_series

[C4 high-memory series]: https://cloud.google.com/compute/docs/general-purpose-machines#c4_series


## Locally-attached NVMe storage

Configuring swap on nodes to use locally-attached NVMe storage allows
Materialize to spill to disk when operating on datasets larger than main memory.
This setup can provide significant cost savings and provides a more graceful
degradation rather than OOMing. Network-attached storage (like EBS volumes) can
significantly degrade performance and is not supported.

### Swap support

The Materialize [Terraform module](https://github.com/MaterializeInc/materialize-terraform-self-managed/tree/main/gcp/examples/simple) supports configuring swap out of the box.

## CPU affinity

It is strongly recommended to enable the Kubernetes `static` [CPU management policy](https://kubernetes.io/docs/tasks/administer-cluster/cpu-management-policies/#static-policy).
This ensures that each worker thread of Materialize is given exclusively access to a vCPU. Our benchmarks have shown this
to substantially improve the performance of compute-bound workloads.

## Recommended metadata database sizing

<p>Self-managed Materialize uses an external PostgreSQL <strong>metadata database</strong> to
store its catalog and to coordinate the state of the objects it keeps up to
date. Every durable object that updates continuously (materialized views,
sources, sinks, and tables) produces a steady stream of small writes to the
metadata database. Metadata-database load therefore scales with the <strong>number of
continuously-updating objects</strong>, not with the volume of data flowing through
them.</p>
> **Note:** The sizing figures below assume the
> [`persist_pg_consensus_read_committed`](/self-managed-deployments/configuration-system-parameters/)
> system parameter is **enabled**. Enable it before sizing against these
> numbers. Materialize version `v26.33+` is required to set this parameter.

<h3 id="safe-operating-point">Safe operating point</h3>
<p>The primary factor that dictates the size of the metadata database is the
number of durable objects Materialize keeps continuously fresh (materialized
views, sources, sinks, and tables). Data volume, the query rate against
Materialize, and cluster size do not materially change metadata database load.
For example, a larger cluster running the same number of materialized views
places roughly the same load on the metadata database.</p>
<p>It is recommended that you size the metadata database so that its
<strong>steady-state CPU stays below 60%</strong>. The headroom between ~60% and full
utilization provides capacity to absorb everyday load variance, background
database maintenance, and Materialize zero-downtime upgrades.</p>


### Cloud SQL machine types

For the Cloud SQL for PostgreSQL instance that backs the metadata database, we
recommend:

- The **Enterprise Plus** edition with a **performance-optimized (N-series)**
  machine type, which provides the 1:8 vCPU-to-memory ratio recommended for the
  metadata database. Avoid shared-core machine types (`db-f1-micro`,
  `db-g1-small`) in production.
- A **regional (highly available)** configuration for production.

| Deployment size | `tier` | vCPU / memory | Continuously-active objects (~60% CPU) |
|---|---|---|---|
| Entry / small production | `db-perf-optimized-N-4` | 4 / 32 GB | ~4,500 |
| Recommended default | `db-perf-optimized-N-16` | 16 / 128 GB | ~18,000 |

## TLS

When running with TLS in production, run with certificates from an official
Certificate Authority (CA) rather than self-signed certificates.

## Upgrading guideline

Whe upgrading:

- **Always** check the [version-specific upgrade
  notes](/self-managed-deployments/upgrading/version-notes/).

- **Always** upgrade the operator **first** and ensure version compatibility
  between the operator and the Materialize instance you are upgrading to.

- **Always** upgrade your Materialize instances **after** upgrading the operator
  to ensure compatibility.

## Node pool resizing

The VM type of a Kubernetes node pool is immutable on EKS, AKS, and GKE, so
changing it triggers a `destroy + create` that fails while Materialize pods are
still running on the pool. The supported pattern is to add a second pool with
the new VM type, roll out the Materialize instance so new pods land on it, and
then drop the old pool.

For the full procedure, see
[Resize node pools](/self-managed-deployments/deployment-guidelines/resize-node-pools/).