CHOOSING THE RIGHT REPORT
Because of the extensive reporting options available in the Google Ads API, determining the correct report for a particular business need can be tricky.
Use the chart below to determine the most suitable report, then check out the details for that report on the Report Types page.
Please note that due to the nature of each report, aggregating different reports and comparing numbers might not always yield the same result (in the UI as well as through the API). One example might be a report on keyword level vs on campaign/account level yielding different results, which occurs because not all campaigns can contain keywords (e.g. Display campaigns may not contain keywords, Brand campaigns would).
Source Copyright: https://developers.google.com/adwords/api/docs/guides/reporting
The report download request may time out on extremely large data sets. There is no explicit data size limit; however, due to a variety of factors, the server may return an error if the report is too large.
If you encounter timeouts or errors, try a shorter date range or use predicates to break up the report request into multiple, smaller requests. For example, instead of running a single report for all campaigns, you could submit multiple requests that each filter for a subset of Campaign IDs.
It is possible to fetch up to 2,500 accounts within a single Datastream for Google Ads. It is possible to fetch data from deleted ads/campaigns.