Michael S. Hanson wrote:
On May 22, 2006, at 9:07 PM, Raphael Fraser wrote:
> I wish Stata could have more than one data set in memory.
I'm curious: (1) What could you accomplish under such a setup that
you cannot currently (given the many data management commands already
in Stata)? (2) How would one prevent data management complications
(same name for different variables in different datasets; specifying
which dataset(s) to write to, frequency and/or sample period
mismatches, etc.) that do not arise under the current setup?
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I think that Stata loads the dataset into memory in order to allow certain
efficiencies (e.g., vectorized operations) that wouldn't be possible
otherwise--i.e., operating on the dataset file one observation at a time.
I'm curious: does *any* data-management/statistical analysis software
package load more than one entire dataset in memory at one time? Maybe
Raphael meant: to have more than one dataset file open for manipulation at
a time, such as what SAS does or perhaps what relational database management
systems do. And, for that matter, you can emulate the same from within
Stata, using the -odbc- suite of commands and SQL. Unlike SAS, you cannot,
however, analogously invoke SQL statements on native Stata dataset files.
But, as Michael mentioned, it's not certain that you would frequently need
to, given Stata's repertoire of data-management commands.
Joseph Coveney
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