Jean-Luc Lachance <jllachan@nsd.ca> writes:
> What would be involved in adding version and visibility to the index?
* Index bloat. An index entry is currently 8 bytes plus the index key,
eg 12 bytes for an int4 index. Version info would add 12 bytes.
Doubling the size of indexes would double the time for index scans.
* Update costs. Instead of one place to update when a row is updated,
now all the associated index entries would have to be updated too.
regards, tom lane