Extract parquet statistics from `Interval` columns about arrow-datafusion HOT 5 CLOSED

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...while looking into this I noticed, that there are no statistics written for an Interval, which is also described here.

@alamb I guess we can't extract any statistics here? And writing any tests that check we have no statistics written, does not seem to be very helpful?

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@alamb I guess we can't extract any statistics here? And writing any tests that check we have no statistics written, does not seem to be very helpful?

I actually think these would be helpful then as soon as there are statistics we can hook them up to the tests. If you had time to write the tests that would be great. We can then perhaps file a ticket in parquet-rs for supporting writing statistics to interval types.

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sure I can do that; from the top of my mind - the fn run() from the struct Test panics if we can't extract any statistics, which is the case here. So I'd prepare as much as possible (creating record batches, adding a Scenario, writing those tests) but for now would assert should panic - does this make any sense to you @alamb?

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I did some digging in order to find out why / or where the writing of those statistics is not supported (yet).
Since I'm not familiar with the parquet impl, here are my findings, which might be useful in a follow-up ticket in arrow-rs.

1. When trying to fn write_slice() the min, max values are never updated due to a filter-condition; that checks if the type is INTERVAL
2. In order to support updating the min max values, we need to handle the comparison of INTERVAL here

I think this should be possible, or put differently, I don't see the reason yet, why this is not supported?
Somethin similar (comparing FixedLenByteArrays) is already done for DECIMAL here?

Perhaps, you have some more information on this @alamb - otherwise this might be enough information to file a ticket in arrow-rs?

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