Re: pgStatTuple

On Fri, Feb 24, 2006 at 05:03:58PM -0500, Lane Van Ingen wrote:
> I want to use pgStatTuple to analyze performance problems when visiting user
> sites; it is a good tool. I know how to set it up; but I couldn't find an
> interpretation of what it generates as a result, so I can be sure of
> interpreting its output correctly and fully.

Have you seen README.pgstattuple? Here's an excerpt:

table_len -- physical table length in bytes
tuple_count -- number of live tuples
tuple_len -- total tuples length in bytes
tuple_percent -- live tuples in %
dead_tuple_len -- total dead tuples length in bytes
dead_tuple_percent -- dead tuples in %
free_space -- free space in bytes
free_percent -- free space in %

It can be educational to create a table to play with and watch
pgstattuple's output change depending on what you do (insert, update,
delete, vacuum, etc.).

> Can anyone help? May also require definition of 'tuple' when used in a
> PostgreSQL sense, also.

Tuple, row, and record are generally used synonymously; tuple seems
to be the more common term in discussions of theory. If that's too
broad a generalization then maybe somebody will provide a more
precise explanation.

--
Michael Fuhr