st: file size problems

[Jeph Herrin <junk@spandrel.net>]

I'm using Stata 9.2 on WinXP (SP2), updated.

I have a file which is 500mb, but when I load it into
Stata, it requires 825mb. That doesn't seem right:

. dir first.dta
 500.7M   8/19/06 18:33  first.dta

. u first.dta, clear

. d

Contains data from first.dta
  obs:    75,006,197
 vars:             3                          19 Aug 2006 18:33
 size:   825,068,167 (12.6% of memory free)
---------------------------------------------------


This is a problem, because WinXp will only allocate 900mb to Stata (anyone
know how to change this? the machine has 4gb). The first thing I want to do
when I load this file is:

. keep if month<mdy(1,1,2000)

however:

no room to add more variables due to width
    An attempt was made to add a variable that would have increased the memory 
required to store an observation beyond
    what is currently possible.  You have the following alternatives:

     1.  Store existing variables more efficiently; see help compress.

     2.  Drop some variables or observations; see help drop.  (Think of Stata's 
data area as the area of a rectangle;
         Stata can trade off width and length.)

     3.  Increase the amount of memory allocated to the data area using the set 
memory command; see help memory.
r(902);



I can't drop any other variables (note that there are only 3). Any ideas? In
particular, is there an alternative to "keep" that doesn't add a variable?

thanks,
Jeph
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