Netezza used to store query execution plans as ascii files in the /nz file system. Active plans would be kept in /nz/data/plans and completed plans kept in /nz/kit/log/planshist/current/. The problem with this was that anytime you wanted a plan file you would have to log onto the system to collect it.
Now, there is a SQL interface to capture the actual execution plan. Beginning v7.0, you can type following from your SQL client (where 78752 is the plan #):
show planfiles 78752;
This will dump the plan file to your screen. If using nzsql, prefix this with:
Or re-direct it to a file. If using Aginity or another ODBC/JDBC/OLEDB SQL client, copy and paste the output to a file for further analysis.