On Fri, 2009-12-04 at 10:43 -0500, Tom Lane wrote: > Simon Riggs <si...@2ndquadrant.com> writes: > > As I pointed out here > > http://archives.postgresql.org/pgsql-hackers/2009-12/msg00056.php > > we only need to use 3 bits not 4, but it does limit tuple length to 4096 > > for all block sizes. (Two different options there for doing that). > > Limiting the tuple length is a deal-breaker.
If people that use 32kB block sizes exist in practice, I note that because tuples are at least 4 byte aligned that the first 2 bits of the length are always unused. So they're available for those with strangely long tuples, and can be used to signify high order bytes and so max tuple length could be 16384. With tuples that long, it would be better to assume 8-byte minimum alignment, which would put max tuple length back up to 32KB again. None of that need effect people with a standard 8192 byte blocksize. -- Simon Riggs www.2ndQuadrant.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers