How to make a layer without extra file or table column

[Myunghwa Hwang]

Hello, lists!

I'm trying to do some analysis and then show its results as a new layer.
Source data for analysis is in a shp file or a postgis data table.
In my case, I don't need to make new feature and I want to use 
analysis results as a new column. Till now, for this, I made a new dbf
file or inserted the results to a new data table. But it's kind of slow.
So what I want to know is if there is a way that directly use data in 
memory for data source for a new layer, and if so, how to do. 
If there is anyone who already experienced this problem, 
please help me. Thank you in advance.