From dec25013c8f9fb7659d5cb1e28457955ca2b1634 Mon Sep 17 00:00:00 2001
From: Martin Weinelt <hexa@darmstadt.ccc.de>
Date: Sun, 16 Jun 2024 00:45:49 +0200
Subject: [PATCH] haumea/zrepl: create pg checkpoint before taking snapshot

Creating a checkpoint flushes all memory to disk, and applies all WAL
files to persistent storage, forward-paying the cost of WAL replay, but
on the other hand making snapshots much cheaper.

https://zrepl.github.io/master/configuration/snapshotting.html#job-hook-type-postgres-checkpoint
https://www.postgresql.org/docs/current/sql-checkpoint.html
https://www.postgresql.org/docs/current/wal-configuration.html
---
 delft/haumea/zrepl.nix | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/delft/haumea/zrepl.nix b/delft/haumea/zrepl.nix
index 481a5dc3..bccc1e6b 100644
--- a/delft/haumea/zrepl.nix
+++ b/delft/haumea/zrepl.nix
@@ -24,6 +24,12 @@
         type = "periodic";
         interval = "5m";
         prefix = "zrepl_snap_";
+        hooks = [ {
+          # https://zrepl.github.io/master/configuration/snapshotting.html#postgres-checkpoint-hook
+          type = "postgres-checkpoint";
+          dsn = "host=/run/postgresql user=root sslmode=disable";
+          filesystems."rpool/safe/postgres" = true;
+        } ];
       };
       pruning = {
         keep_sender = [