5 min read
Logical replication is more flexible than physical and more fragile. Use it when you need partial replication, cross-version, or selective sync. Don't use it for HA.
Database Topic Archive
Replication and WAL Articles
Replica lag, WAL growth, failover readiness, hot standby behavior, and replication slots.
5 min read
Physical replication slots make sure replicas can catch up after a disconnect. They also make sure your primary's disk fills if a replica is gone and forgotten.
5 min read
Read replicas are eventually consistent. The application's view of "after I wrote, my read should see it" is often wrong by milliseconds, sometimes by minutes.
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Failover is mostly fine when you do not need it and broken when you do. Here is how to know which you have.
4 min read
If your Postgres disk is growing and you cannot identify the culprit, replication slots are usually the answer. Here is the diagnostic sequence.
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Replication monitoring is not one lag number. You need to know stale-read risk, slot retention, replay delay, WAL growth, and whether failover would help or hurt.
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Aurora's replica lag has different mechanics than vanilla streaming replication. The dashboard metric "replica lag" can be misleading. Here is what it actually measures.
3 min read
WAL problems usually look like disk problems too late. Monitor generation rate, checkpoints, archiving, replication lag, and slot retention before pg_wal owns the incident.