Getting large amount of contacts - missing some contacts and some are duplicated

Hello,

i developed a tool for synchronizing contacts and companies from our crm system to freshdesk - our crm system is the master. This tool runs in a 3 hour interval. First, it loads all 26k contacts over the rest API down. Unfortunately, the rest API is missing a call for getting all contacts like a bulk export over rest. To have a good performance by considering the rate limits of the rest API, I send 100 get calls parallel per minute using paging and a maximum of 100 rows for each page.

First the good news: it often works fine. But more and more often I get not all contacts and some contacts are duplicates on my list. I think it has to do with getting a large amount of data over up to 3 minutes. When I start synchronizing early in the morning, it mostly works fine, throughout the day mostly not. Another interesting thing: the error with duplicate contacts happens nearly always in the same data area. The tool logs the name of the contacts and almost all duplicate contacts begin with “Michael”.

Is there any solution for this kind of problem? Maybe it helps to sort the contacts by a specific field, actually I use no/the default sort.

Thank you.