[Solved] Error: "Prepared statement ... already exists" when repeating query

I just tried the default docker image with Digital Ocean's hosted Postgres (which recommends using connection pools), and ran into the error "Prepared statement ... already exists" when repeating the same query.

@benjie quickly pointed out the following on Discord:
> PostGraphile uses prepared statements as a minor performance optimisation, but this causes issues if you’re running external connection pools in addition to PostGraphile’s native connection pooling. You can disable prepared statements by setting the environment variable POSTGRAPHILE_PREPARED_STATEMENT_CACHE_SIZE=0

In my case, since PostGraphile already has connection pools built-in, I just connected directly to the database rather than the Postgres connection pool, and everything works fine.

I wasn't sure where this might go in the documentation, so just quickly posting this as an issue in case it helps anyone.

Commencez par le corps de l’issue, qui documente l’erreur liée aux requêtes préparées lors de l’utilisation d’un pool de connexions Postgres externe avec PostGraphile. Aucun fichier de documentation ni aucun test n’est indiqué ; commencez donc par localiser la documentation pertinente sur la gestion du pool de connexions ou la configuration. Le travail est terminé lorsque le contournement utilisant POSTGRAPHILE_PREPARED_STATEMENT_CACHE_SIZE=0 et les indications de connexion directe à la base de données sont clairement documentés.

Rédigé par le modèle d'indexation à partir du texte de l'issue.