Having used -parmby- recently and having some understanding of what
Roger is discussing, I'd like to offer the following.
From my interpretation of how Stata stores data, the ability to -use
in ##/##- would require the record indexes to be created by completely
loading the data. I am currently working on a 4 million record
dataset and was able to run a quick test with a little program:
n di "Begin: " _n c(current_date) " " c(current_time) _n
use dss_data_05_06 in 1/1000, clear
n di "Load using in 1/1000" _n c(current_date) " " c(current_time) _n
use dss_data_05_06, clear
n di "Ordinary load" _n c(current_date) " " c(current_time)
Output:
Begin:
12 Sep 2007 15:02:46
Load using in 1/1000
12 Sep 2007 15:02:56
Ordinary load
12 Sep 2007 15:03:06
I switched the loading order and regardless, the load took 10 seconds
either way. I don't think you can use this optimization.
DC Elliott
(posted by David Airey)
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