Streaming Replication: walsender and walreceiver
Streaming replication keeps a second server as an exact twin of the first.
It ships the primary's change-log to the standby, which replays every change as it arrives. Because it copies the physical changes bit for bit, the twin has to run the same PostgreSQL version on the same kind of hardware.
Pro members see the rest of this lesson
- A 4-step state diagram: Commit → Send → Flush → Replay
- The full mechanism: what PostgreSQL does internally, in source terms
- 1 SQL query you can run, each labelled by how it was verified
- 1 transcript captured on PostgreSQL 17.10
- The closing insight, the mistake it prevents, and what it changes in your work
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Check it against the source1 citation in postgres/postgres · file, symbol and line verified on REL_17_STABLE
Primary symbol: WalSndLoop · line 2831
Anchored to postgres/postgres on REL_17_STABLE and cross-checked against the manual for PostgreSQL 15–18. Every query here was run and its output captured on a throwaway PostgreSQL 17.10 lab; corrections are noted inline. §27.2.5 Streaming Replication in the official docs →
Connected
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What comes before, after, and alongside it.
Part of these pathways
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