Re: Redundant databases/real-time backup - Mailing list pgsql-admin

From Ragnar Kjørstad
Subject Re: Redundant databases/real-time backup
Date
Msg-id 20001130125312.C22723@vestdata.no
Whole thread Raw
In response to Redundant databases/real-time backup  (root <root@dennis.veritime.com>)
List pgsql-admin
On Thu, Nov 30, 2000 at 12:08:20AM -0800, hamptone wrote:
> > [ about processing the postgresql log ]
>
> Thanks for the tips Ragnar...although I wish you would explain more about
> FIFO.  The only thing that rings a bell on this is First In First Out from
> the inventory chaper of my accounting textbook.....

I guess you're familiar with pipes?
like:
cat logfile | program

a FIFO is pretty much the same thing, only it has a filename. This mean
a process can write to the FIFO thinking it's writing to a regular file,
and another process can read from the FIFO thinking it's reading from a
regular file.

This makes it possible to process the file in realtime instead of in
batch, if you choose to.

If you use a FIFO, your postgresql process will block if there is
nothing actually reading from the FIFO. This means two things:
1. If the program processing the logfile dies, postgresql die too.
2. The postgresql server can't work faster than your logfile processer.

But the good news is your backupserver will always be up-to-date.



--
Ragnar Kjørstad

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