In a database table, there can be data columns with changeable values. For example, in an orders table there might be a column called status. When an order is initially written to the database, the status column might contain the value "pending." The order will then be replicated in your Data Warehouse with this "pending" value.
Order statuses can change, though - they won't always be in a pending status. Eventually it could become "complete" or "cancelled." To ensure that your Data Warehouse syncs this change, the column will need to be rechecked for new values.
How does this fit in with the replication methods we discussed? The processing of rechecks varies based on the chosen replication method. The Modified_At replication method is the best choice for processing changing values, as rechecks don't have to be configured. The Auto-Incrementing Primary Key and Primary Key Batch Monitoring methods require recheck configuration.
When using either of these methods, changeable columns must be flagged for rechecking. There are three ways to do this:
- An auditing process that runs as part of the update will flag columns to be rechecked. Note that the auditor relies on a sampling process and the changing columns may not be caught immediately.
- You can set them yourself by selecting the checkbox next to the column in the Data Warehouse manager, clicking Set Recheck Frequency, and choosing an appropriate time interval for when we should check for changes.
- A member of the Magento BI Data Warehouse team can manually mark the columns for rechecking in your Data Warehouse. If you're aware of changeable columns, contact the team to request that rechecks are set. Please include a list of columns, along with frequency, with your request.
Did you know? Setting a recheck on a primary key column doesn’t check the column for changed values. The table will be checked for deleted rows and any deletions will then be purged from the Data Warehouse.
When a column is flagged for rechecking, you can also set how often a recheck occurs. If a particular column will change less often, choosing a less frequent recheck can optimize your update cycle.
Frequency options are:
- always - recheck occurs during every update
- daily - recheck occurs first post-midnight update for your declared timezone
- weekly - recheck occurs post-9pm Friday update every week for your declared timezone
- monthly - recheck occurs post-9pm Friday update every 4 weeks for your declared timezone
- once - occurs only in the next update (a one-off refresh)
As update times are correlated to how much data needs to be synced, we recommend choosing a daily, weekly, or monthly recheck instead of every update.
Managing recheck frequencies
Recheck frequencies can be managed in the Data Warehouse by clicking on a table name and then checking individual columns. The syncing status and recheck frequency (the Changes? column) will display for each column in the table.
To change the recheck frequency, click the checkbox next to the column(s) you want to change then click the Set Recheck Frequency dropdown and set the desired frequency.
You might sometimes see Paused in the Changes? column. This value will display when the table's replication method is set to Paused.
We recommend reviewing these columns to both optimize your updates and ensure changeable columns are being rechecked. If the recheck frequency for a column is unnecessarily high given how often the data will change, we recommend decreasing it to optimize your updates.
Feel free to contact us with questions or to inquire about current replication methods or rechecks.