Statistics cached for transaction duration causing stale data

Statistics values are cached until the end of the current transaction by default. Long-running transactions will see static statistics even as actual database activity continues. Time delta between accessing different statistics can cause significant skew in cached values.

For interactive analysis or expensive queries, set stats_fetch_consistency to 'snapshot' to minimize skew (with increased memory usage) or 'none' if statistics are only accessed once. Call pg_stat_clear_snapshot() to discard cached values within a transaction and force fresh data retrieval.