Timing considerations and synchronous replication v5.6

Being asynchronous by default, peer nodes might lag behind. This behavior makes it possible for a client connected to multiple PGD nodes or switching between them to read stale data.

A queue wait function is provided for clients or proxies to prevent such stale reads.

The synchronous replication features of Postgres are available to PGD as well. In addition, PGD provides multiple variants for more synchronous replication. See [Commit scopes(../commit-scopes) for an overview and comparison of all variants available and their different modes.