udt | libudt with udtc wrapper

Your query doesn't have a WHERE filtering clause; it asks for all records in the resultset of that big join.

The query planner would choose index seek over index scan if you wanted just one, or a very small number, of rows in your resultset. index scan is a two-step process: first it seeks to the first row it needs (which could be the first row in the index). It then scans the index sequentially to get the rest of the rows it needs.

Scanning a covering index is an efficient way to get a multi-row resultset: the query can be satisfied from the index, so the query planner doesn't have to bounce back and forth between the index and the table data itself.

All is well here.

You need to declare these nested UDTs as frozen, like:

It was a mistake in my query. The correct query would be:

In order to work in a sheet module, the above code should be adapted as following

1. The receiver sheet code should be adapted in the next way:

That's weird, but the type name don't suggest it's public API anyway :)

You can always roll your own:

As noted in the comments, user-defined types must be defined in an Object Module to be passed as a variant to a function. It's a misleading phrase because an Object Module is actually a Class Module.

However, it is possible to read the element count of an array of UDTs defined in a Module (or any array for that matter). You would achieve this by reading the SAFEARRAY structure (https://docs.microsoft.com/en-us/windows/win32/api/oaidl/ns-oaidl-safearray) which you access from the array pointer rather than the array itself.

So you could pass the array pointer into your function and thereby avoid the problem of trying to coerce the array to a variant. If, as you say in your question, you are certain the array is only 1 dimension, then coding is relatively straightforward. Arrays of more than one dimension could be used but you'd need a little bit of pointer arithmetic (still pretty trivial, though) to get to the dimension you're after. Note that the code below assumes 64-bit:

I think this is related to Go Issue #13400. There seems to be an issue with the namespace prefixes. You can in fact ignore the prefixes in your struct tags while Unmarshaling.

The following code should work for you:

You need to assign it to the element of ID that has a matching type, not the ID itself. Like

Not all Long variables can be LongPtr variables. And in 64-bit version OleCreatePictureIndirect is in oleaut32 instead of olepro32.