Allow to pass an instance of Pool when instantiating PostgresRecordManager

[josemussa]

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Feature request

I want to suggest adding the possibility to pass an existing Pool instance when instantiating PostgresRecordManager. This would enable the reuse of an existing database connection pool.

I've implemented this logic already and I'm ready to open a pull request.

Motivation

Currently, the PostgresRecordManager does not allow passing an existing Pool instance, which forces the creation of a new connection pool even when one already exists.

Proposal (If applicable)

const pool = new pg.Pool(config.postgresConnectionOptions);
const providedPoolRecordManager = new PostgresRecordManager("test", {
  ...config,
  pool,
});

[josemussa]

Fix merged here #5677