| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Zeugswetter Andreas SB SD" <ZeugswetterA(at)spardat(dot)at> |
| Cc: | "Curtis Faith" <curtis(at)galtair(dot)com>, "Bruce Momjian" <pgman(at)candle(dot)pha(dot)pa(dot)us>, "Hannu Krosing" <hannu(at)tm(dot)ee>, "Pgsql-Hackers" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Analysis of ganged WAL writes |
| Date: | 2002-10-08 13:45:35 |
| Message-ID: | 1445.1034084735@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
"Zeugswetter Andreas SB SD" <ZeugswetterA(at)spardat(dot)at> writes:
> Can the magic be, that kaio directly writes from user space memory to the
> disk ?
This makes more assumptions about the disk drive's behavior than I think
are justified...
> Since in your case all transactions A-E want the same buffer written,
> the memory (not it's content) will also be the same.
But no, it won't: the successive writes will ask to write different
snapshots of the same buffer.
> The problem I can see offhand is how the kaio system can tell which
> transaction can be safely notified of the write,
Yup, exactly. Whose snapshot made it down to (stable) disk storage?
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Ron Johnson | 2002-10-08 13:50:52 | Re: [GENERAL] Large databases, performance |
| Previous Message | Robert Treat | 2002-10-08 13:40:44 | Re: Hot Backup |