title: What is the significance of a config value wrapped in parentheses in postgresql.conf?
body: <p>In a guide for tuning postgres for Nominatim OSM imports, the guide recommends the following settings being modified at the time of writing:</p>
  <pre><code>shared_buffers = 2GB
  maintenance_work_mem = (10GB)
  autovacuum_work_mem = 2GB
  work_mem = (50MB)
  effective_cache_size = (24GB)
  synchronous_commit = off
  checkpoint_segments = 100 # only for postgresql &lt;= 9.4
  max_wal_size = 1GB # postgresql &gt; 9.4
  checkpoint_timeout = 10min
  checkpoint_completion_target = 0.9
  </code></pre>
  <p>When I tried to actually put them in parentheses, the values were throwing &quot;invalid line&quot; errors.</p>
  <pre><code>Error: invalid line 131 in /etc/postgresql/12/main/postgresql.conf: work_mem = (50MB)           # min 64kB
  </code></pre>
  <p>So here is my question: What is the significance/purpose of putting the values in parentheses? Is this just an error? If it's not an error, then how do I do it without getting an error?</p>
  <p>Thanks in advance!</p>
  <p>EDIT: Sorry if this is a question I could've figured out online, I promise I did try but I couldn't find anything.</p>