On Wed, Jun 07, 2006 at 01:48:50PM +0200, Zdenek Kotala wrote: > Koichi Suzuki wrote: > >I've once proposed a patch for 64bit transaction ID, but this causes > >some overhead to each tuple (XMIN and XMAX). Pgbench with 64bit > >transaction ID has to pay about a couple of percent of performance. > >If 64bit transaction ID is a reasonable fix, I've already posted this > >patch. Anyone can apply this to later versions. > Did you check performance on 32-bit or 64-bit systems and 64-bit binary > version of PGSQL? I think that today is not problem to have 64-bit > architecture and 64-bit ID should increase scalability of Postgres.
I doubt performance is the issue directly. Increasing the size of the transaction counter would increase the size of narrow tables by maybe 30%. That's 30% more disk space and 30% more memory usage in some places. Maybe at some point it'll be worth it, but right now I don't think those commodoties are cheap enough to use like this for fairly marginal benefits. Beside, memory bandwidth hasn't grown anywhere enar as fast as memory space, so it's always a good idea to use as little memory as possible. Have a nice day, -- Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/ > From each according to his ability. To each according to his ability to > litigate.
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