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Re: st: Does Blasnik's Law apply to -use-?

From   David Airey <[email protected]>
To   [email protected]
Subject   Re: st: Does Blasnik's Law apply to -use-?
Date   Thu, 13 Sep 2007 13:23:58 -0500

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)


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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