Is it possible to have multiple PostgreSQL instances for one PGDATA folder, shared in a storage for example?

And if is not, is there is some kind of RDBMS capable of something like this?

  • Do you mean multiple databases within a single cluster? Or multiple clusters? If the latter, where does the requirement come from that they share PGDATA directories -- could they share a parent directory that has multiple PGDATA directories in it?
    – jmelesky
    Sep 25, 2019 at 15:28

1 Answer 1


No, that is impossible. PostgreSQL protects against that as good as it can, but if you manage to start a second postmaster, instant data corruption will ensue.

This question makes me wonder why you want that:

  • It cannot be scalability, because you have I/O as a bottleneck.
  • It cannot be high availability, because the shared storage is a single point of failure.

Such architectures like Oracle RAC are ill-conceived and mostly useless; nobody would design such a system these days.

The way to go is a shared-nothing cluster like patroni.

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