Re: pg_stat_*_columns?

On 6/5/15 6:51 AM, Joel Jacobson wrote:
>
> 1. I think it would be helpful for DBAs to better understand their own
> system.
> Finding unused *tables* is today easy thanks to pg_stat_*_tables, but
> knowing if something is accessing a *column* or not is not easy.
> In my case all our database access is via sprocs, so I can just grep the
> source code for the column name to see if something is using it, but
> most DBAs probably don't have that luxury.

I have wanted this exact thing when considering vertical partitioning. 
It's easy to tell from a size standpoint what columns are good 
candidates for putting in a 'side table', but it's very hard to know how 
often columns are actually used.

BTW, I think the right way to measure this would be how many rows were 
returned for queries referencing a column. Simply knowing how many 
queries reference a column doesn't tell you much; you want to know how 
much column data was actually pulled out.
-- 
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Data in Trouble? Get it in Treble! http://BlueTreble.com