資料庫設定

FATAL:  sorry, too many clients already
https://github.com/docker-library/docs/tree/master/postgres#database-configuration
```
postgres -c 'shared_buffers=256MB' -c 'max_connections=200'
```

pq: could not resize shared memory segment. No space left on device
https://stackoverflow.com/a/56754077
https://docs.docker.com/compose/compose-file/
```
shm_size: '2gb'
```