Excerpts from Andres Freund's message of vie sep 16 14:27:33 -0300 2011: > Hi, > On Friday 16 Sep 2011 17:36:20 Matthew Wilcox wrote: > > Does the query planner need to know the exact number of bytes in the file, > > or is it after an order-of-magnitude? Or to-the-nearest-gigabyte? > It depends on where the information is used. For some of the uses it needs to > be exact (the assumed size is rechecked after acquiring a lock preventing > extension) at other places I guess it would be ok if the accuracy got lower > with bigger files (those files won't ever get bigger than 1GB). One other thing we're interested in is portability. I mean, even if Linux were to introduce a new hypothetical syscall that was able to return the file size at a ridiculously low cost, we probably wouldn't use it because it'd be Linux-specific. So an improvement of lseek() seems to be the best option. -- Álvaro Herrera <alvherre@xxxxxxxxxxxxxxxxx> The PostgreSQL Company - Command Prompt, Inc. PostgreSQL Replication, Consulting, Custom Development, 24x7 support -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
