Re: RTREE Index on primary key generated by a sequence

Jean-Paul ARGUDO <jean-paul(dot)argudo(at)IDEALX(dot)com> writes:
> Since my english is not so fluent, I found on the net a little
> explication about Reverse Key Indexes (not RTREE, sorry :).

> As an explication, you could read there the point 9 :
> http://oracle.oreilly.com/news/oraclepp_0900.html

> ... Reverse key indexes reverse the
> bytes in each index entry, causing
> sequential entries to be dispersed across the
> index tree.

Hmm. I think you could implement that with a custom index opclass
consisting of operators that flipped the bytes before comparison.
Not clear that it'd really buy you enough to be worth the trouble,
but if someone wants to try it...

> ... One
> trade-off involved with using this
> technique is that by its nature, reverse key indexes
> cannot be used as the basis for an index
> range scan.

The way this would show up in Postgres is that you would use the
standard integer = operator as the = member of the opclass, but
all the other members would be byte-reversed-comparison operators
that would never be useful in real-world queries.

regards, tom lane