On Tue, Jun 24, 2003 at 03:34:48PM -0500, Todd Burke wrote:
> 
> Hello
> 
> 1/ I have a search engine which crawls auction sites and returns
> information which is inserted into a mysql database.  This activity
> represents on average about 3 inserts per second with a combined payload
> of 450 bytes per second added to the database.  This updating occurs
> continuously throughout the day. Since this activity puts a burden on the
> machine on which it occurs (not only the mysqld inserts but also the
> scripts and http client activity), I am planning to dedicate one box to
> the crawling/inserting and replicate the data to one (or possibly more)
> other servers.  These slave servers will handle all client requests
> (almost exclusively reads).

[snip]

> My questions are:
> 
> Since the updating occurs throughout the day and the same amount of data
> has to be eventually inserted into the slaves I assume the updating will
> require the same amount of resources (disk, cpu usage) on the slaves as on
> the master - the same number of writes will occur on the slaves.

Yes.

> So the the benefit of this configuration (in terms of performance)
> is that it is the extra processing required to do the crawling will
> be offloaded to the one master server, not the resources required
> for the mysql writes.

The real benefit is that clients reading the data don't block writes
on the master AND you can have many, many, many more clients reading
the data this way--more than a single machine could ever handle.

> I assume inserts done thru replication are not more efficient than
> regular inserts.

Right.

> What is the performance hit of replication and is there a way to
> limit the effect of the writes on the slave servers, thru
> configuration parameters, for example, or would it even make sense
> to take the slave offline at regular intervals while replication is
> taking place?

The performance hit of replication on the master is trivial.  I've had
40 slaves (or was it 30?) replicating from a master with no
side-effects.

I can think of no reason to pause replication on the slave(s).

> 2/ Is there any documentation on handling and configuring large tables? 

Yes, here's something I wrote to explain it a bit more than the manual
does (or used to):

  http://jeremy.zawodny.com/blog/archives/000796.html

Jeremy
-- 
Jeremy D. Zawodny     |  Perl, Web, MySQL, Linux Magazine, Yahoo!
<[EMAIL PROTECTED]>  |  http://jeremy.zawodny.com/

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