If you see a heap size error when running the Data Wizard, you can adjust how many records we process per execution. The fewer the records, the less memory used. The import will run a little slower, but for most people this will not be noticeable.
There are two settings that control how many records the Data Wizard processes at a time, and both should be reduced when you hit a heap size error.
- Go to the Mailchimp Settings tab.
- Select Maintenance from the menu.
- Click on Settings from the dropdown next to Reports.
- Locate the 'Data Wizard SOQL records per execution' setting and change the value to 100.
- Locate the 'Data Wizard Report records per execution' setting and change the value to 100.
- Save the settings.
If necessary, you can reduce them further, ultimately to 1 record each. If you reach 1, then you should probably check other custom code, flows, or processes that are running outside of our product.
What else can I do to avoid heap limits?
Heap is increased by the amount of data that needs to be loaded into memory to process a transaction (single or batch). Here are some general ways heap is increased when processing the import.
- There are many records pulled by the report. We have to callout and load the report and data into memory to process it. Lowering the batch size usually fixes this, but you can also filter the report to omit records we won't process: No email, already opted out, no recent edits that need to be mapped to Mailchimp.
- There is a large volume of data in each record we process, namely many columns. Removing columns you aren't mapping, if any, so we don't load them unnecessarily
- There is custom automation running on the records we are trying to save during the import (Mailchimp Members and Audiences mainly). We don't recommend automation off our objects, and it should always run asynchronously.
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