DataSync's Replication Properties¶
Replication Properties¶
The replication process needs some specific information to run the process correctly, for that reason three properties were created:
- ExportMarker.
- LastUpdated.
- LastUpdatedUTC.
We are going to explain each one:
Export Marker¶
It is a Boolean value (1 or 0) that represents if a tuple was modified after the last replication process was executed. In case a tuple has been created or updated, the value of Export Marker cell is 1. When the replication process is executed, this value is changed again from 1 to 0.
Last Updated¶
When a tuple is updated, the value of this cell is replaced by the current date. In most cases, this value is excluded.
Last Updated UTC¶
Since the ships are in constant motion and travel through different time zones, this property is created to contains the same information as the LastUpdated property but using the UTC time zone.
Example¶
We have the following table.
| Id | Name | SectionId | ExportMarker | LastUpdated | LastUpdatedUtc |
|---|---|---|---|---|---|
| 1 | Refinement | 10001 | 1 | 03/31/2021 10:35:50 | 03/31/2021 13:35:50 |
| 2 | Reparations | 10002 | 1 | 03/31/2021 10:35:50 | 03/31/2021 12:35:50 |
If any change in the row with id 1 is done, the LastUpdated and LastUpdatedUtc columns of that row will be updated automatically, and the ExportMarker is set to 1.
When a replication process is executed, it looks for all the tuples for which the export marker value is one and takes them into account for the process ignoring all the tuples with the value in zero. Once the process starts and the tuples were exported, the export marker value in the tuples is changed to zero. If we take the table bellow:
| Id | Name | SectionId | ExportMarker | LastUpdated | LastUpdatedUtc |
|---|---|---|---|---|---|
| 1 | Refinement | 10001 | 0 | 03/31/2021 11:35:50 | 03/31/2021 13:35:50 |
| 2 | Reparations | 10002 | 0 | 03/31/2021 10:35:50 | 03/31/2021 12:35:50 |
We can see that the value of ExportMarker for the Id 1 was changed to zero.