Hi Everyone, I’m trying to use PGPool in front of a PG database and Ecto’s using it but all commands failed. Here are the logs that I figured out.

$ mix ecto.create
** (Mix) The database for App.Repo couldn't be created: command timed out

Also, I hit PGPool through postgrex directly and more info turned out.

iex(1)> {:ok, pid} = Postgrex.start_link(hostname: "localhost", port: 7432, username: "postgres", password: "adminpassword", database: "postgres", prepare: :unnamed)
{:ok, #PID<0.594.0>}
iex(2)> Postgrex.query!(pid, "SELECT 1;", [], [timeout: 20000])
** (DBConnection.ConnectionError) tcp recv: closed (the connection was closed by the pool, possibly due to a timeout or because the pool has been terminated)
    (postgrex 0.15.7) lib/postgrex.ex:249: Postgrex.query!/4
{"msg":"Postgrex.Protocol (#PID<0.596.0>) disconnected: ** (DBConnection.ConnectionError) client #PID<0.592.0> timed out because it queued and checked out the connection for longer than 20000ms\n\n#PID<0.592.0> was at location:\n\n    :prim_inet.recv0/3\n    (postgrex 0.15.7) lib/postgrex/protocol.ex:2838: Postgrex.Protocol.msg_recv/4\n    (postgrex 0.15.7) lib/postgrex/protocol.ex:1241: Postgrex.Protocol.recv_parse/3\n    (postgrex 0.15.7) lib/postgrex/protocol.ex:1208: Postgrex.Protocol.recv_parse_describe/4\n    (postgrex 0.15.7) lib/postgrex/protocol.ex:1028: Postgrex.Protocol.parse_describe_flush/3\n    (db_connection 2.3.1) lib/db_connection/holder.ex:316: DBConnection.Holder.holder_apply/4\n    (db_connection 2.3.1) lib/db_connection.ex:1257: DBConnection.prepare/4\n    (db_connection 2.3.1) lib/db_connection.ex:1250: DBConnection.run_prepare/4\n    (db_connection 2.3.1) lib/db_connection.ex:1262: DBConnection.run_prepare_execute/5\n    (db_connection 2.3.1) lib/db_connection.ex:1359: DBConnection.run/6\n    (db_connection 2.3.1) lib/db_connection.ex:557: DBConnection.parsed_prepare_execute/5\n    (db_connection 2.3.1) lib/db_connection.ex:550: DBConnection.prepare_execute/4\n    (postgrex 0.15.7) lib/postgrex.ex:235: Postgrex.query_prepare_execute/4\n    (postgrex 0.15.7) lib/postgrex.ex:247: Postgrex.query!/4\n    (stdlib 3.14) erl_eval.erl:680: :erl_eval.do_apply/6\n    (elixir 1.11.3) src/elixir.erl:280: :elixir.recur_eval/3\n    (elixir 1.11.3) src/elixir.erl:265: :elixir.eval_forms/3\n    (iex 1.11.3) lib/iex/evaluator.ex:261: IEx.Evaluator.handle_eval/5\n    (iex 1.11.3) lib/iex/evaluator.ex:242: IEx.Evaluator.do_eval/3\n    (iex 1.11.3) lib/iex/evaluator.ex:220: IEx.Evaluator.eval/3\n","level":"error","datetime":"2021-02-24T17:16:11.000088Z","function":"disconnect/2","file":"lib/db_connection/connection.ex"}
iex(2)>

PGPool Logs:

2021-02-24 17:15:51: pid 166: LOG:  DB node id: 0 backend pid: 9337 statement: Parse: SELECT 1;
2021-02-24 17:15:51: pid 166: LOG:  DB node id: 0 backend pid: 9337 statement: D message
2021-02-24 17:16:11: pid 166: ERROR:  unable to read data from frontend
2021-02-24 17:16:11: pid 166: DETAIL:  EOF encountered with frontend

Ecto Config:

config :app, App.Repo,
  URL: databaseUrl,
  show_sensitive_data_on_connection_error: true,
  pool_size: 20,
  timeout: 60_000

My suspect is on the incompatibility DB Connection module with PSQL protocol, Should be noted I tried psql 11 and 13 versions, all had same issue.

did you experience same issue?