Re: MAXTHR and SLAVETHR in sys.aux_stats$

From: Jonathan Lewis <>
Date: Thu, 15 May 2008 08:20:49 +0100
Message-ID: <032801c8b65c$340a5d00$0200a8c0@Primary>

If you generate a 10053 trace file in 10.2, the file will contain the following section (the numbers are something I set for a demo):

Using WORKLOAD Stats

CPUSPEED: 800 millions instructions/sec
SREADTIM: 12 milliseconds
MREADTIM: 26 millisecons

MBRC: 8.000000 blocks
MAXTHR: 12000 bytes/sec
SLAVETHR: 2000 bytes/sec

So I think you have to assume it's bytes per second. Setting them manually -

The effect I see from playing with them is that the CBO uses maxthr/slavethr as an upper limit on the notional degree of parallelism when doing the arithmetic.

However, there is some sort of sanity check between the absolute values for these stats and (I think, but haven't yet investigated) the implied throughput from MBRC and MREADTIM, so if you want to set them manually and have them work predictably you need to work out how the sanity check goes and get all the figures self-consistent.


Jonathan Lewis

Author: Cost Based Oracle: Fundamentals

The Co-operative Oracle Users' FAQ

  • Original Message ----- From: "David Aldridge" <> To: "Oracle List" <> Sent: Wednesday, May 14, 2008 8:02 PM Subject: MAXTHR and SLAVETHR in sys.aux_stats$

> Does anyone know what units these are supposed to be in, or have any caveats
> about setting them manually?

Received on Thu May 15 2008 - 02:20:49 CDT

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