## AlloyDB for PostgreSQL special cases

URL: https://docs.atlan.com/apps/connectors/database/alloydb/postgresql/how-tos/special-cases

> AlloyDB for PostgreSQL special cases - fleets of instances, very large databases, cross-cloud tenants, and connection paths that rewrite the port.

Fleets of instances, very large databases, cross-cloud tenants, and connection paths that rewrite the port.

## Many instances across dev / QA / prod projects

Each AlloyDB *instance* is a separate connection in Atlan, with its own host, credentials, and crawler. Real deployments run **10+ instances** across environment tiers. What scales:

- **Self-deployed runtime:** one runtime (per routable network) covers every instance - the marginal cost of instance #11 is one more crawler config.
- **PSC:** one endpoint per instance. Batch all Service Attachment URLs into **one support ticket**, clearly labeled per instance, and propose a hostname scheme (e.g. `alloydb-<env>-<nn>.example-corp.internal`).
- **Naming:** connection names become part of asset addresses. Agree a convention before crawling - renaming later means re-crawling.

## Very large instances (millions of assets)

AlloyDB fleets with **3–5 million+ assets** produce a distinct class of issues: the crawl *connects fine* but runs many hours or fails at the *publish* step (writing assets into Atlan), sometimes affecting other running workflows. If your instance is at this scale:

- Start with a crawl **scoped to one schema** to validate connectivity and permissions cheaply.
- Use include/exclude filters and the "exclude regex for tables & views" option to keep partition-heavy schemas manageable.
- Tell support *before* the first full crawl - publish throughput can be tuned for the initial load.
- A long-running or publish-failing workflow after a successful test connection is **not a connectivity problem** - don't spend time on firewalls; see [Troubleshooting AlloyDB connectivity](https://docs.atlan.com/llms/connectors/alloydb-postgresql/troubleshooting-alloydb-connectivity/llms.txt).

## Atlan tenant on AWS or Azure, AlloyDB on Google Cloud

Fully supported and common. Two things change:

- The **egress IPs** you allowlist are those of your tenant's hosting cloud (e.g. an Azure region's addresses), not Google addresses. Get them from support with your tenant URL.
- If you migrated a database from another cloud (e.g. RDS → AlloyDB) and previously used a private link, that link **does not carry over** - the private path must be rebuilt for GCP (PSC) or replaced by the runtime. Update the existing connection's credentials and host rather than creating a new connection, so asset history is preserved.

## Load balancers, proxies, and non-default ports with IAM auth

If traffic reaches the database through a load balancer or proxy that **listens on a different port** than the database (e.g. LB port 5433 → database 5432), password auth works but **IAM auth can fail**: the short-lived IAM token is signed for the port you configured, and the database rejects a token signed for the wrong port.

- Symptom: `FATAL: PAM authentication failed` or auth errors only on the connections that go through the port-rewriting hop.
- Fix: use the advanced/auth port option so the token is signed for the database's real port - or mention the topology on a support ticket.

## Which IAM options exist where

| Auth method | Direct | Self-deployed runtime | Notes |
|---|---|---|---|
| Username / password (built-in) | ✓ | ✓ | Simplest; credentials in Atlan (encrypted) or your vault (SDR) |
| IAM user | ✓ | ✓ | Uses a short-lived access token (~1 h) - fine for one-off testing, wrong for schedules |
| IAM service account | ✓ | ✓ | Service-account key; recommended for scheduled crawls |
| IAM Workload Identity Federation | ✗ | ✓ (GKE only) | No stored key at all; requires the runtime on GKE |

See [Crawl AlloyDB for PostgreSQL](https://docs.atlan.com/llms/connectors/alloydb-postgresql/crawl-alloydb-postgresql/llms.txt) for the full crawler configuration. Note the IAM options are not AWS-only - the matrix above is for AlloyDB on Google Cloud.

_Last updated: 8 October 2026._

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