Re: [PROPOSAL] VACUUM Progress Checker.

Hello,

Please find attached updated patch with an interface to calculate command
progress in pgstat.c. This interface currently implements VACUUM progress
tracking .
A column named percent_complete has been added in pg_stat_activity to
report progress.

VACUUM calls the progress calculation interface periodically at an interval
specified by pgstat_track_progress GUC in ms.
Progress calculation can be disabled by setting pgstat_track_progress as
-1.

Remaining_time for VACUUM is not included in current patch to avoid
cluttering pg_stat_activity with too many columns.
But the estimate as seen from previous implementation seems reasonable
enough to be included in progress information , may be as an exclusive view
for vacuum progress information.

GUC parameter 'pgstat_track_progress' is currently PGC_SUSET in line with
'track_activities' GUC parameter. Although IMO, pgstat_track_progress can
be made PGC_USERSET in order to provide more flexibility to any user to
enable/disable progress calculation provided progress is tracked only if
track_activities GUC parameter is enabled.

In this patch, index scans are not taken into account for progress
calculation as of now .

Thank you,
Rahila Syed.