"Zeugswetter Andreas DAZ SD" <ZeugswetterA@spardat.at> writes:
> I think I recall that lseek may have a negative effect on some OS's
> readahead calculations (probably only systems that cannot handle an
> lseek to the next page eighter) ? Do you think we should cache the
> last value to avoid the syscall ?
We really can't, since the point of doing it is to find out whether any
other backends have extended the file since we last looked. Also, IIRC
seqscan startup does a similar lseek() anyhow, so having the planner do
one will make no difference to the readahead or lack of it in a
subsequent seqscan.
regards, tom lane
