Create database table from memory

[radeusgd]

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[radeusgd]

cc @jdunkerley I wanted to figure out if we want to have these duplicate_rows.
It could make the user's life easier to show them indices of rows of one of the duplicated groups.

OTOH, the user can always compute these themselves and computing them is pretty costly for big tables.

Third thing is, when trying to compute them I realised it's actually not that easy. I'm thinking if we should add some methods that could help. I'm thinking of Aggregate_Column.As_Vector which could create a vector of all elements of a single group. Or something else that could help - as currently finding out duplicated rows is not that easy - unless I'm not seeing some cool trick.

[GregoryTravis]

I think this would be very useful; I would think you could do it with a Vector.group_by on the rows, returning a Vector of Vectors, and show the inner vectors with > 1 row. Assign this to me if you like.

[radeusgd]

Ok, I reported this as #6437 and we can handle it when we have a bit of spare time.

returning a Vector of Vectors

I guess that may require extending Aggregate_Column, but yeah that sounds like a good idea.

[GregoryTravis]

I think this would be very useful; I would think you could do it with a Vector.group_by on the rows, returning a Vector of Vectors, and show the inner vectors with > 1 row. Assign this to me if you like.