I doubt the documentation for old_snapshot_threshold is going to be
understood by many ordinary users. What is a "snapshot", first of all?
Why would a snapshot be old? Why is that a problem? What can I do to
avoid it? What are the circumstances in practice where this issue would
arise, and what are the trade-offs? Where can I see existing snapshots
and how old they are?
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Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services