title: Postgres indexing hangs indefinitely
body: <p>I'm trying to create a GIN index on a jsonb column, no other operations are currently happening on this table(none at all). The table is about 3million rows, at about 10gb. I've tried 3 times, once for 3 days(over the weekend), and the next 2 times for several hours. It hangs indefinitely. The last 2 times I looked at the index size, each time the index stops around 290mb both times. The operation never succeeds or fails, just hangs for several hours. The CPU usage remains consistently around 1%, the memory usage barely budges, the IO remains pretty low also. I tried to VACUUM the database, I have the same issue, it just hangs indefinitely.</p>
  
  <p>Queries are slow, sometimes they just timeout. I have no idea what is wrong.</p>
  
  <p>The server itself isn't starving for resources, it has 2 cpus and 4GB of RAM.</p>