pageserver: use proper GC cutoffs at external interfaces #10707
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jcsp
changed the title
jcsp
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t/bug
arpad-m
reviewed
Feb 6, 2025
| @@ -616,7 +616,10 @@ impl Timeline { | |||
| // GC cutoff could be before the branching point and we cannot create a new branch | |||
| // with LSN < `ancestor_lsn`. Thus, pick the maximum of these two to be | |||
| // on the safe side. | |||
| let min_lsn = std::cmp::max(*gc_cutoff_lsn_guard, self.get_ancestor_lsn()); | |||
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I think this needs a rebase (cc #10678)
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Problem
We validate branch creations against both the latest_gc_cutoff (the one we've applied) and the planned GC cutoff (the projection of PITR time onto LSN space).
However, in our external interfaces we were using only the latest_gc_cutoff, so a caller who looks up an LSN with get_lsn_by_timestamp might get an unusable LSN, or someone who looks at TimelineInfo output might also get an unusable LSN.
Closes: #10639
Summary of changes