| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Cc: | Jim Cox <shakahshakah(at)gmail(dot)com>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: TODO item: adding VERBOSE option to CLUSTER [with patch] |
| Date: | 2008-10-13 12:30:00 |
| Message-ID: | 7877.1223901000@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> No, I was thinking of something along the lines of:
> INFO: clustering "public.my_c"
> INFO: complete, was 33%, now 100% clustered
> The only such measure that we have is the correlation, which isn't very
> good anyway, so I'm not sure if that's worthwhile.
It'd be possible to count the number of order reversals during the
indexscan, ie the number of tuples with CTID lower than the previous
one's. But I'm not sure how useful that number really is. Also it's
not clear how to preserve such functionality if cluster is
re-implemented with a sort.
regards, tom lane
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