Re: How to avoid transaction ID wrap - Mailing list pgsql-hackers

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.

Be careful, the pg_multixact stuff assumes that a MultiXactId is the
same size as TransactionId, so you have to change that too.  I don't
recall offhand if it was defined in a way that would make it "just work"
automatically.  (You'd also have to be careful about it not overrunning
the SLRU files when it's close to the end of 'em.).

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.