Ack the WAL Keep-Alives

[robacourt]

Acknowledge the WAL on keep-alive messages to keep advancing it.

Relevant Discord thread

[netlify]

✅ Deploy Preview for electric-next ready!

Name	Link
🔨 Latest commit	00e0da9
🔍 Latest deploy log	https://app.netlify.com/sites/electric-next/deploys/672248f347d1b2000801c46e
😎 Deploy Preview	https://deploy-preview-1905--electric-next.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[msfstef]

Linking to a relevant article - in AWS RDS there are heartbeats written to the DB every 5 minutes that make the WAL grow very quickly.

I think it makes sense to flush on keep alive messages in order to avoid this happening and this shouldn't mess with our logic in any way. A second set of eyes more familiar with PG would be good (@icehaunter?), but I this might resolve the issue.

We could be smarter about when we ack the WAL in the keep alive if there are performance implications on doing it every time, but I suspect this is already better than letting it grow indefinitely.

[balegas]

Our past experience: #1083

I think it makes sense to flush on keep alive messages in order to avoid this happening and this shouldn't mess with our logic in any way.

Can't see why not. Let's run this on RDS tomorrow and see what happens.