
Morning all ...

	Can someone explain to me how I should read this:

        tablename        |          attname           | avg_width | n_distinct
-------------------------+----------------------------+-----------+------------
 iwantu_pro_week         | uid                        |         8 |         -1
 iwantu_pro_week         | pro_week_agent             |         9 |          9
 iwantu_pro_week         | pro_week_time              |         8 |  -0.976321
 iwantu_pro_week         | pro_week_post              |         5 |          2
 iwantu_pro_week         | pro_week_club              |         2 |          1

n_distinct, I'm taking it, of -1 means its a UNIQUE INDEX, and the
positive numbers are exact #'s ... but, -0.976321? :)

Also, how is the avg_width interpreted?


Wed, 13 Feb 2002 09:31:30 -0400 (AST)
"Marc G. Fournier" <scrappy@hub.org>
pg_stats explained ... ?
"Marc G. Fournier" <scrappy@hub.org> writes:
> n_distinct, I'm taking it, of -1 means its a UNIQUE INDEX, and the
> positive numbers are exact #'s ... but, -0.976321? :)

"Almost unique", evidently.  See stadistinct at
http://www.ca.postgresql.org/users-lounge/docs/7.2/postgres/catalog-pg-statistic.html

> Also, how is the avg_width interpreted?

Just what you'd expect: average stored width, in bytes, of non-NULL
entries in the column.

			regards, tom lane

Wed, 13 Feb 2002 11:06:40 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: pg_stats explained ... ? 