The store's PostgreSQL sized to its machine's memory

Each Patroni member gets a share of its own RAM in its own config.yml:
shared_buffers a quarter (15% beside a control plane or agent),
effective_cache_size, maintenance_work_mem and work_mem scaled to it, all
clamped. It is read again on every server init --patroni, so a machine
given more memory gets the use of it. A single-machine PostgreSQL init
installs is sized the same way, as a shared machine, instead of a fixed
96MB.

The step itself went in with 85025df by accident, in an early form that
restarted PostgreSQL before Patroni had taken the reload, leaving the old
shared_buffers with a restart pending. It now waits for Patroni to report
the restart pending, restarts with restart_pending (replicas first, the
leader last), and restarts a member it finds pending from an earlier run.

Applied to the PoC: pg01 978MB, ctl02 (control plane beside it) 587MB,
both from 128MB; streaming, lag 0, gateways unaffected.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/cli/serverinit_postgres.go

@@ -16,6 +16,7 @@ import (
 	"gitea.mynodes.xyz/ilker/llmgw/internal/agent/discovery"
 	"gitea.mynodes.xyz/ilker/llmgw/internal/agent/provision"
 	"gitea.mynodes.xyz/ilker/llmgw/internal/config"
+	"gitea.mynodes.xyz/ilker/llmgw/internal/pgha"
 	"gitea.mynodes.xyz/ilker/llmgw/internal/store"
 )
 
@@ -348,15 +349,23 @@ func (in *serverInit) setupPostgres(ctx context.Context) (string, error) {
 	}
 
 	if installed {
-		// Its defaults assume it owns the machine. A gateway swapped out to
-		// give the database cache is worse than a smaller cache, and a store
-		// whose working set is megabytes needs little. Only a PostgreSQL init
-		// installed itself: one that was already here may serve something
-		// else that needs its connections.
-		for _, q := range []string{
-			"ALTER SYSTEM SET shared_buffers = '96MB'",
-			"ALTER SYSTEM SET max_connections = 40",
-		} {
+		// Sized to the machine's memory, as one it shares with the gateway:
+		// a gateway swapped out to give the database cache is worse than a
+		// smaller cache, but a knowledge base's vector index is searched
+		// well only from memory. Only a PostgreSQL init installed itself:
+		// one that was already here may serve something else that needs its
+		// connections.
+		meminfo, _ := os.ReadFile("/proc/meminfo")
+		total, ok := pgha.MemTotal(string(meminfo))
+		if !ok {
+			total = 1 << 30
+		}
+		mem := pgha.MemorySettings(total, true)
+		qs := []string{"ALTER SYSTEM SET max_connections = 40"}
+		for _, k := range []string{"shared_buffers", "effective_cache_size", "maintenance_work_mem", "work_mem"} {
+			qs = append(qs, "ALTER SYSTEM SET "+k+" = '"+mem[k]+"'")
+		}
+		for _, q := range qs {
 			if _, err := in.psql(ctx, q); err != nil {
 				return "", err
 			}
@@ -367,7 +376,8 @@ func (in *serverInit) setupPostgres(ctx context.Context) (string, error) {
 		if err := in.waitForPostgres(ctx); err != nil {
 			return "", err
 		}
-		in.done("PostgreSQL sized for a machine it shares (shared_buffers 96MB, 40 connections)")
+		in.done("PostgreSQL sized for a machine it shares, with %d MB of memory (shared_buffers %s, work_mem %s, 40 connections)",
+			total>>20, mem["shared_buffers"], mem["work_mem"])
 	}
 
 	in.setupPgvector(ctx, discovery.DiscoverHost())