On Thu, Sep 19, 2019 at 11:10:46PM -0400, David Steele wrote: > On 9/19/19 11:00 AM, Robert Haas wrote: >> On Thu, Sep 19, 2019 at 9:51 AM Robert Haas <robertmh...@gmail.com> wrote: >> > I intend that we should be able to support incremental backups based >> > either on a previous full backup or based on a previous incremental >> > backup. I am not aware of a technical reason why we need to identify >> > the specific backup that must be used. If incremental backup B is >> > taken based on a pre-existing backup A, then I think that B can be >> > restored using either A or *any other backup taken after A and before >> > B*. In the normal case, there probably wouldn't be any such backup, >> > but AFAICS the start-LSNs are a sufficient cross-check that the chosen >> > base backup is legal. >> >> Scratch that: there can be overlapping backups, so you have to >> cross-check both start and stop LSNs. > > Overall we have found it's much simpler to label each backup and cross-check > that against the pg version and system id. Start LSN is pretty unique, but > backup labels work really well and are more widely understood.
Warning. The start LSN could be the same for multiple backups when taken from a standby. -- Michael
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