: Column Performance in a query

Hello Everyone,

Generally when it comes to query performance, I check how the vacuuming and
statistics collection is performed on Tables and Indexes hit by the query.

Apart from the above i check the code logic ( for any bad joins ) and column
statistics as well.

I got hold of two catalog tables "pg_stats" and "pg_class".

Column "avg_width" and "distinct" in pg_stats gets me lot of sensible
information regarding, column values and size of the column.

Can someone help me know when the values in these columns are bound to
change ? Is it only when ANALYZE runs ?

I am about to calculate lot of metrics depending on above values. Please
help !

Thanks
Venkat