I've found with distributed postgreSQL databases that the optimizer needs more help than you might initially expect. After looking at how the optimizer ineffic

I've found with distributed postgreSQL databases that the optimizer needs more help than you might initially expect. After looking at how the optimizer inefficiently implemented a query, I found a different, but equivalent, way to rewrite the query that could then be efficiently optimized. It's more complicated in the distributed case, because the shard distribution rules have a strong impact on performance. The time needed to re-balance data across shards for a query can be significant.