Maximum number of records

User Chinedu Onyezobi has sent us the following question:

I am Chinedu Onyezobi, a monitoring and evaluation manager with a non-government organization in Nigeria. I am currently setting up an electronic mobile application for collection of over a million records on field. I have read on the survey solution support site on how to set up a local server but am still unclear on the total number of records one can collect on this server. Please, can you confirm the maximum number of records we can collect on this platform.

Survey Solutions limits are documented here:

There is no limit on the number of records that Survey Solutions imposes by design.

That said, the actual capacity limit will depend on:

  1. The characteristics of the server;
  2. The Questionnaire being used for the survey;
  3. The kind of data being collected;
  4. Certain options of the program;
  5. Language;
  6. Behavior of the interviewers;
  7. Types of maps being used.
  8. Version of Survey Solutions
  9. Etc,
  10. etc,
  11. etc

There is no exact formula. (You can try to predict the size of an Excel file (.xlsx format, to a byte precision) if you want to understand the complexity of the problem).

Besides that, there will be soft limits that you will hit first - where the server formally still functions correctly, but the responsiveness degrades. Hence, whether it is still comfortable or acceptable to use is a subjective answer, depending heavily on the user’s patience and/or the situation (which both vary greatly).

Most of the users working with smaller surveys (let’s say in the range of 1-10,000 interviews) need not to be concerned about the limits of this kind at all. If you are planning a national census of tens of millions households, farms or enterprises, then it is not a question that has an answer N, but more of a research project with a large experimental component, to determine the suitability of the hardware and software for a certain operation.

In practice, surveys of millions of observations have been collected with Survey Solutions.

Finally, it is a common misconception, that the max number of observations is limited with the length of the interview key 99-99-99-99 or 100mln records per server. The interview key will become wider (will have 10 or more digits) if Survey Solutions system decides that this is needed.