Hi, Lars!
I ran "Prepare statement" in studio on
select calmonth from pruning_test where calmonth = '201502' /* some comment to ensure uniqueness */;
I unchecked checkbox "Prepare statements before executions", but nothing changed.
When the new statement is prepared or executed (before execution of the new query it must be pepared, right?) HANA loads almost all partitions as shown in the screenshot.
So what we have:
1. Every new statement must be prepared before first execution;
2. You say that Partition pruning works also during preparation. And on your test case it can be clearly seen that it is so - only partitions 14, 39, 64 are loaded during preparation of the new query;
3. When I try exactly the same test case on the HANA Cloud Platform dev. ed. rel. 102 (to eliminate the influence factor of the third-party system) I see that almost all partitions are loaded.
Could you try the same case on the HANA Cloud Platform dev. ed?