How can we improve Microsoft Azure SQL Data Warehouse ?

Distribute nulls evenly - to avoid skew when using hash distribution

My best candidate distribution key is 40% nulls.

At present, distributing on this value will result in one overloaded distribution, where all the nulls will land.

As nulls will never join to any other table, it would suit this use case to have equal distribution of null rows across all distributions, so that the non-null foreign keys can benefit from being distribution aligned.

I understand this would be a change in behaviour, so perhaps a new distribution option could be created i.e. HASH_AND_NULL(my_foreign_key)

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Neil Palmer shared this idea  ·   ·  Flag idea as inappropriate…  ·  Admin →

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