postgres tuning

bundles/postgresql/items.py

@@ -1,5 +1,8 @@
 from bundlewrap.utils.dicts import merge_dict
 
+
+version = node.metadata.get('postgresql/version')
+
 directories = {
     '/var/lib/postgresql': {
         'owner': 'postgres',
@@ -14,6 +17,22 @@ directories = {
     }
 }
 
+files = {
+    f"/etc/postgresql/{version}/main/conf.d/managed.conf": {
+        'content': '\n'.join(
+            f'{key} = {value}'
+                for key, value in sorted(node.metadata.get('postgresql/conf').items())
+        ) + '\n',
+        'owner': 'postgres',
+        'group': 'postgres',
+        'needed_by': [
+            'svc_systemd:postgresql',
+        ],
+        'triggers': [
+            'svc_systemd:postgresql:restart',
+        ],
+    },
+}
 
 svc_systemd['postgresql'] = {
     'needs': [

bundles/postgresql/metadata.py

@@ -1,3 +1,6 @@
+import builtins
+
+
 root_password = repo.vault.password_for(f'{node.name} postgresql root')
 
 defaults = {
@@ -12,6 +15,7 @@ defaults = {
         },
     },
     'postgresql': {
+        'conf': {},
         'roles': {
             'root': {
                 'password': root_password,
@@ -24,6 +28,32 @@ defaults = {
 }
 
 
+@metadata_reactor.provides(
+    'postgresql/conf',
+)
+def conf(metadata):
+    conf = {}
+
+    def limit(value, min=float('-inf'), max=float('inf'), unit=None):
+        result = int(builtins.max([builtins.min([max, value]), min]))
+        return str(result) + unit if unit else result
+
+    ram = metadata.get('vm/ram', None)
+    if ram:
+        conf['max_connections'] = limit(ram/50, min=100)
+        conf['shared_buffers'] = limit(ram/20, min=128, unit='MB')
+        conf['work_mem'] = limit(ram/500, min=4, max=64, unit='MB')
+        conf['temp_buffers'] = limit(ram/500, min=8, max=64, unit='MB')
+        conf['effective_cache_size'] = limit(ram/3, min=4096, unit='MB')
+        conf['maintenance_work_mem'] = limit(ram/50, min=64, unit='MB')
+
+    return {
+        'postgresql': {
+            'conf': conf,
+        },
+    }
+
+
 @metadata_reactor.provides(
     'zfs/datasets',
 )