pq: could not resize shared memory segment. No space left on device

You can increase shm size by remounting it without restarting/rebuilding container

mount -o remount,size=256m -t tmpfs /var/lib/docker/containers/your-container-id/mounts/shm

Change your-container-id and needed size (256m)

Sorry for the late reply. Building a new image is not necessary. But you must be sure the container is recreated, and you are not using the old one. Docker-compose file must be changed with, adding shm_size at service level. Build section is not necessary.

version: "3.5"
services:

#other containers go here..

 postgres:
    restart: always
    image: postgres:10

    #THIS MUST BE ADDED AT SERVICE LEVEL
    shm_size: 1gb 

    hostname: postgres
    container_name: fiware-postgres
    expose:
      - "5432"
    ports:
      - "5432:5432"
    networks:
      - default
    environment:
      - "POSTGRES_PASSWORD=password"
      - "POSTGRES_USER=postgres"
      - "POSTGRES_DB=postgres"
    volumes:
      - ./postgres-data:/var/lib/postgresql/data

Then you must completely recreate the container

docker-compose rm postgres 
# alternatively you can docker-compose down to destroy all containers
docker-compose up -d

to destroy the old container and create a new one.

You can check the change inside the container (enter with docker-compose exec postgres bash) and run df -h | grep shm

Reference:docker SHM_SIZE /dev/shm: resizing shared memory

After increasing shm_size: did not help me out, I turned to db optimization and found that adding some missing indexes solved this error in my particular case.

Specifically I had several views that used joins on fields w/o indexes, and once the db got to typical size (1M rows in "many" side of joins) these errors began.

This is because docker by-default restrict size of shared memory to 64MB.

You can override this default value by using --shm-size option in docker run.

docker run -itd --shm-size=1g postgres

or in docker-compose:

db:
  image: "postgres:11.3-alpine"
  shm_size: 1g

Check this out. More info here.

Hope this helps.