Extension of maximum number of variables by "maxvar" is not possible:

[Rene Macon]

I have Stata 15 with a Stata/SE license. So extension of memory space should be possible. However using "set maxvar 8000" results in the following error message:

 . set maxvar 8000
no; data in memory would be lost

My memory usage is currently:

. memory usage

  Memory usage
                                            used                allocated
    ---------------------------------------------------------------------
    data                              11,290,795               67,108,864
    strLs                                      0                        0
    ---------------------------------------------------------------------
    data & strLs                      11,290,795               67,108,864

    ---------------------------------------------------------------------
    data & strLs                      11,290,795               67,108,864
    var. names, %fmts, ...             1,750,469                2,762,465
    overhead                           1,081,344                1,082,136

    Stata matrices                             0                        0
    ado-files                                  0                        0
    stored results                             0                        0

    Mata matrices                              0                        0
    Mata functions                             0                        0

    set maxvar usage                   5,281,738                5,281,738

    other                              2,439,320                2,439,320
    ---------------------------------------------------------------------
    grand total                       20,441,286               78,674,523

Has anybody an idea, why "set maxvar 8000" does not work?
Thanks a lot!

[William Lisowski]

At the time that you issued the set maxvar command you had a dataset in memory, and set maxvar is concerned - I believe - that it will cause that data to be cleared and possibly lose some of your work. So issue the set maxvar command when you have no data in memory.

clear
set maxvar 8000

[Rene Macon]

I have already checked this possiblity. Unfortunately,

 
  . set maxvar 8000 no; data in memory would be lost

appears even after I have reloaded my database and without any other commands inbetween.

Also, if I use "clear" all the variables in my database disappear. What could that be?

[William Lisowski]

Run the set maxvar command before you load your dataset while there is no dataset in memory.

The clear command does exactly what is documented in the output of the help clear command - it removes the current dataset from memory. So the after set maxvar you need to reload the dataset.

[Rene Macon]

That worked! Thanks a lot! I thought "set maxvar" would always be related to a specific database. Now I understand that it changes the software configuration in general.

I read the "maxvar" manual description but didn't get that. Thanks again!

[William Lisowski]

I thought "set maxvar" would always be related to a specific database. Now I understand that it changes the software configuration in general.

Note that the change is for the duration of your Stata session and reverts to the previous value at the end of the session. As a user of Stata/SE I have permanently set maxvar at the maximum

set maxvar 32767, permanently

and with my datasets have never encountered a lack-of-memory situation that would have been remedied by freeing some of the 38,830,849 bytes allocated as a consequence of this value of maxvar.

[Rene Macon]

Note that the change is for the duration of your Stata session and reverts to the previous value at the end of the session. As a user of Stata/SE I have permanently set maxvar at the maximum

Thanks for this useful information! I would appreciate, if the Reference Manual would be a bit more explicit about such things.