Re: [GENERAL] Function to return per-column counts?
On Thu, Sep 28, 2017 at 3:31 PM, Seamus Abshere <seamus@abshere.net> wrote:
> > > Does anybody have a function lying around (preferably pl/pgsql) that
> > > takes a table name and returns coverage counts?
> >
> > What is "coverage count"?
Ah, I should have explained better. I meant how much of a column is
null.
Basically you have to
0. count how many total records in a table
1. discover the column names in a table
2. for each column name, count how many nulls and subtract from total
count
If nobody has one written, I'll write one and blog it.
Thanks!
Seamus
PS. In a similar vein, we published
http://blog.faraday.io/how-to-do-histograms-in-postgresql/ which gives
plpsql so you can do:
SELECT * FROM histogram($table_name_or_subquery, $column_name)
--
Seamus Abshere, SCEA
https://www.faraday.io
https://github.com/seamusabshere
https://linkedin.com/in/seamusabshere --
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general
I can't really do the full query for you, but the following should be able to give you a head start:
SELECT c.relname AS table,
a.attname AS column,
a.attnum AS colnum,
s.stanullfrac as pct_null,
s.stadistinct
FROM pg_class c
JOIN pg_attribute a ON a.attrelid = c.oid
JOIN pg_statistic s ON (s.starelid = c.oid AND s.staattnum = a.attnum)
WHERE c.relname = 'your_table_name'
AND a.attnum > 0
ORDER BY 3
a.attname AS column,
a.attnum AS colnum,
s.stanullfrac as pct_null,
s.stadistinct
FROM pg_class c
JOIN pg_attribute a ON a.attrelid = c.oid
JOIN pg_statistic s ON (s.starelid = c.oid AND s.staattnum = a.attnum)
WHERE c.relname = 'your_table_name'
AND a.attnum > 0
ORDER BY 3
--
Melvin Davidson
I reserve the right to fantasize. Whether or not you
wish to share my fantasy is entirely up to you.
I reserve the right to fantasize. Whether or not you
wish to share my fantasy is entirely up to you.
В списке pgsql-general по дате отправления: