Re: zheap: a new storage format for PostgreSQL

> In PostGIS workloads, UPDATE table SET geom = ST_CostyFunction(geom, magicnumber); is one of biggest time-eaters that happen upon initial load and clean up of your data. It is commonly followed by CLUSTER table using table_geom_idx; to make sure you're back at full speed and no VACUUM is needed, and your table (usually static after that) is more-or-less spatially ordered. I see that zheap can remove the need for VACUUM, which is a big win already. If you can do something that will allow reorder of tuples according to index happen during an UPDATE that rewrites most of table, that would be a game changer :)
>

If the tuples are already in the order of the index, then we would
retain the order, otherwise, we might not want to anything special for
ordering w.r.t index.  I think this is important as we are not sure of
the user's intention and I guess it won't be easy to do such
rearrangement during Update statement.