The versions operator shows array versions.

Synopsis

• versions(named_array);

• versions(vmax:true, ns: ns_name);

• versions(vmax:true);

Summary

• versions(named_array) lists all versions of a specific array.

• versions(vmax:true, ns: ns_name) lists the maximum version of every array in namespace ns_name (or all for all namespaces).

• versions(vmax:true) behaves the same as above, except that it takes the namespace from the current session.

Example

To create an array with two versions, do the following:

1. Create an array containing one cell with the value 10:

   AFL% create array A <val:double>[i=1:1]; AFL% store(build(A, 10), A);

   
   The output is:

   {i} val {1} 10

2. Change the values to 20:

   AFL% store(build(A, 20), A)

   
   The output is:

   {i} val {1} 20

To get information about the versions of A, do the following:

1. Use the versions operator to list the versions of array A:

   AFL% versions(A); 

   
   The output is:

   {No} version_id,timestamp {1} 1,'2016-02-26 18:19:39' {2} 2,'2016-02-26 18:21:28'  

2. Use the versions operator to list the maximum version of all arrays in the namespace public

   AFL% versions(vmax:true, ns: public)

   The output is:

   {Idx} version_id,timestamp,name {0} 2,'2023-11-10 17:01:16','A'

To examine the data of different versions:

1. Use the scan operator and the @ array version specifier to access version 1

   AFL% scan(A@1);  

    

   The output is:

   {i} val {1} 10

2. Use the scan operator and the @ array version specifier to access version 2

   AFL% scan(A@2);  

    

   The output is:

   {i} val {1} 20