Sync-Data-with-DSTIME

Other Sync-Tools just work from Caché/IRIS to Caché/IRIS.
Synchronizing your data to some external DB requires some other solution.

The solution is available in Caché/IRIS since quite some time and works excellent.
^OBJ.DSTIME does the magic.
https://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=D2IMP_ch_current#D2IMP_C23869

It was built to allow data synchronization with DeepSee.
It keeps a very simple journal on Object/Table changes by signaling Modified,New,Deleted
This could be useful not only for DeepSee but for any other type of Table Synchronization.

The Global ^OBJ.DSTIME has 2 additional features

• It is wrapped in a persistent class %SYSTEM.DSTIME
  https://docs.intersystems.com/latest/csp/documatic/%25CSP.Documatic.cls?PAGE=CLASS&LIBRARY=%25SYS&CLASSNAME=%25SYSTEM.DSTIME
  so you can use it also as normal SQL Table to select your changes

• It maintains a version ID (named DSTIME) that allows control of synchronized junks:
  + you fetch the last version
  + increase the version
  + and then you upload your changes wherever you require them

And as you do the synchronization by pure SQL your target can be any DB understanding SQL.

I extended class %SYSTEM.DSTIME to allow Pure SQL Operation

The demo class is a copy of Sample.Person amd it runs in namespace IRISAPP.

Typical scenario:

  IRISAPP>write ##class(OBJ.Person).Populate(15)  
  15  
  IRISAPP>do $system.SQL.Shell()  
  IRISAPP>>DELETE FROM OBJ.PERSON WHERE ID IN (2,5,9)  
  IRISAPP>>Update OBJ.PERSON SET NAME='Robert' WHERE ID IN (3,7)  

Now we can take a look on OBJ.DSTIME

  SAMPLES>>SELECT * FROM OBJ.DSTIME  
DSTIME  ClassName       ObjectId     FilingOp     LastVersion  Version

0       OBJ.Person      1            1            0            0

0       OBJ.Person      2            2            0            0

0       OBJ.Person      3            0            0            0

0       OBJ.Person      4            1            0            0

0       OBJ.Person      5            2            0            0

0       OBJ.Person      6            1            0            0

0       OBJ.Person      7            0            0            0

0       OBJ.Person      8            1            0            0

0       OBJ.Person      9            2            0            0

0       OBJ.Person      10           1            0            0

0       OBJ.Person      11           1            0            0

0       OBJ.Person      12           1            0            0

0       OBJ.Person      13           1            0            0

0       OBJ.Person      14           1            0            0

0       OBJ.Person      15           1            0            0

next we set a new version

  SELECT OBJ.DSTIME_NewVersion()  

and generate some more Persons

  SAMPLES>write ##class(OBJ.Person).Populate(15) 

These new records have a new version.
So you may export easily all changes from the previous version of OBJ.DSTIME
during normal operation while any additional changes are logged with the new version.

e.g.

  INSERT INTO MySQL.Person (name,DOB,SSN)   
    select Name,DOB,SSN  from OBJ.Person p  
          JOIN OBJ.DSTIME d  
          on p.ID = d.ObjectId  
          where d.ClassName='OBJ.Person'  
          and Version = 0   

Attention
This solution uses the actual content of your Objects / Tables.
So if the version of the object log is out of date you may see some newer content if additional changes were applied since.

Article in DC