Ühel kenal päeval, K, 2006-08-09 kell 10:57, kirjutas Tom Lane:
> Hannu Krosing <[EMAIL PROTECTED]> writes:
> > Ühel kenal päeval, K, 2006-08-09 kell 12:56, kirjutas Simon Riggs:
> >> Methinks it should be the Write pointer all of the time, since I can't
> >> think of a valid reason for wanting to know where the Insert pointer is
> >> *before* we've written to the xlog file. Having it be the Insert pointer
> >> could lead to some errors.
> > What is the difference ?
> Insert points to the next byte to be written within the internal WAL
> buffers.  The byte(s) preceding it haven't necessarily gotten out of
> those buffers yet.  Write points to the end of what we've actually
> written to the kernel,

I assume that it also points to the byte after what is written to
kernel, or is it tha last byte written ?

>  and there's also a Flush pointer that points
> to the end of what we believe is down on disk.
> Simon's point is that if you're going to use pg_current_xlog_location()
> to control partial shipping of xlog files, you probably want to know
> about the Write location, because that indicates the limit of what
> is visible to an external process.

Yes, that is what I need

>                       regards, tom lane
Hannu Krosing
Database Architect
Skype Technologies OÜ
Akadeemia tee 21 F, Tallinn, 12618, Estonia

Skype me:  callto:hkrosing
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