Re: Using oracle dump (quickly!)

From: Hans Forbrich <hforbric_at_yahoo.net>
Date: Wed, 25 Feb 2004 18:06:22 GMT
Message-ID: <yu5%b.37475$n17.4264@clgrps13>

Ron wrote:

>>Usually a buffer parameter of 8M is more than sufficient

>
>
> I use 100M+ as well - always works. Hope user can decide if bigger is
> better
>
>

>>Setting LOG_BUFFER too anything
>>higher than 1M is useless, as the buffer is written to disk when 1M is
>>dirty.

>
>
> As far as I remember, 1M is upper bound for _log_io_size under Oracle8
> (according to Steve Adams as well). _log_io_size is 1/3 of the log buffer
> expressed in log blocks. So setting to LOG_BUFFER 4M during the big import
> would not hurt
>
>

>>3 Nologging doesn't have any impact on import at all.
>>It is only applicable using direct path operations, i.e. in inserts
>>using the /*+ append */ and using sqlloader in direct mode. Import
>>doesn't work in direct mode.
>>

>
>

(Still top posting, I see. Bad habits die hard, I guess.)

You might want to look at
http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96533/memory.htm#29731

where you'll find the following statement

"
A reasonable first estimate for such systems is to make the log buffer 1 MB. On most systems, sizing the log buffer larger than 1m does not provide any performance benefit. Increasing the log buffer size does not have any negative implications on performance or recoverability. It merely uses extra memory.
"

I wouldn't be surprised to see some benefit from 4M or 8M in certain circumstances, but the above statement indicates that 100M is likely a bit of useless overkill.

(Apparently your organization has money to waste - at least in extra memory. Since it's not being used effectively anyway, pass some this way <g>)

/Hans Received on Wed Feb 25 2004 - 12:06:22 CST