I though about the possibilities of progress visualization - and one possibility is one or two special column in pg_stat_activity table - this info can be interesting for VACUUM started by autovacuum too.
Yes, I suggest just a single column on pg_stat_activity called pct_complete
trace_completion_interval = 5s (default)
Every interval, we report the current % complete for any operation that supports it. We just show NULL if the current operation has not reported anything or never will.
We do this for VACUUM first, then we can begin adding other operations as we work out how (for that operation).
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Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services