gmake with tables in a SQL database as dependencies (postgres)?

[forkandwait]

Hi all,

Say I want to run a summary analysis of something once a day and email it, but
only if there is a change in some table stored in a Postgres database, OR there
is a change in the analysis code in a given directory.

Is there a pattern for using gmake to run the analysis/ email script when the
dependencies have changed?

I can imagine a trigger that touch'es a file in the directory on a change. 
Another approach would be a more convoluted shell script to get modification
time from triggered metadata, and then touch a file, and then run gmake.  But
neither of these feel very graceful. 

I am sorry that I don't have a real example, but I am hopeful this situation has
come up before and someone can sketch a general approach they are happy with.