haskell-bee-pgmq

PostgreSQL/PGMQ broker implementation for haskell-bee.

This package provides a PostgreSQL-backed message queue broker using PGMQ (PostgreSQL Message Queue).

Database initialization

Notice that upon broker initialization, this calls PGMQ.initialize which tries very hard to create the pgmq schema for you.

If you also want to pre-create the database itself, with some given user, you can try something like this:

import Shelly qualified as SH

createDBIfNotExists :: Text -> Text -> IO ()
createDBIfNotExists connStr dbName = do
  -- For the \gexec trick, see:
  -- https://stackoverflow.com/questions/18389124/simulate-create-database-if-not-exists-for-postgresql
  (_res, _ec) <- SH.shelly $ SH.silently $ SH.escaping False $ do
    let sql = "\"SELECT 'CREATE DATABASE " <> dbName <> "' WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = '" <> dbName <> "')\\gexec\""
    result <- SH.run "echo" [sql, "|", "psql", "-d", "\"" <> connStr <> "\""]
    (result,) <$> SH.lastExitCode
    
  return ()