How do I merge in batches?
Available only in the Google Docs Add-on
If you have 100s of rows to merge it is best if you batch your merges as Google services may not be able to handle the load at once and it will start issuing errors (such as NetworkError: Connection failure due to HTTP -1).
It may be best to merge by 50 or 80 rows depending on how many pages and merge fields you have in your document template.
You can apply batching by clicking the Options link and set the following fields:
Create a column in your sheet and call it Merged? (but you can call it anything you want).
From the Add-ons' sidebar click the Options button.
Assign this Merged? column to the Track Merged Rows and Merge Specific Rows fields. This will allow the add-on to track which rows have been already merged.
Set the Batch Size to how many rows you want to merge at one go.
Save the Options and hit the blue Merge button form the sidebar.
This will confirm the batch size for the merge.
Once the batch is done you need to manually hit the merge button again to do the next batch.
Confirm the batch size