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System Stats strategy
A few days ago I received an email about system statistics. I decided it was worth replying to, provided I wrote my response up as a series of questions and answers on the blog. (I don’t tend to...
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System Statistics 3
In a recent thread on one of the Oracle Forums, someone asked the question: So, in general, if systems statistics are in effect, would you or would you not make any adjustments to the...
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System Statistics
I wrote an article about system statistics / CPU Costing for Oracle magazine a few years ago – and last week I realised that I’ve never supplied a link to it in the notes and comments I’ve made about...
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System Stats
A quick collation – and warning – for 11.2 MOS (Metalink): Bug 9842771 - Wrong SREADTIM and MREADTIM statistics in AUX_STATS$ [ID 9842771.8] (needs MOS account) Comment from Sokrates in a Charles...
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System Stats
Several years ago I wrote the following in “Cost Based Oracle – Fundamentals” (p.47): The maxthr and slavethr figures relate to throughput for parallel execution slaves. I believe that the figures...
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maxthr – 2
Actually, there hasn’t been a “maxthr – 1″, I called the first part of this series“System Stats”. If you look back at it you’ll see that I set up some system statistics, excluding the maxthr and...
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maxthr – 3
In part 1 of this mini-series we looked at the effects of costing a tablescan serially and then parallel when the maxthr and slavethr statistics had not been set. In part 2 we looked at the effect of...
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sreadtim
Here’s a question that appeared in my email a few days ago: Based on the formula: “sreadtim = ioseektim + db_block_size/iotrfrspeed” sreadtim should always bigger than ioseektim. But I just did a...
View Articlegather_system_stats
What happens when you execute dbms_stats.gather_system_stats() with the ‘Exadata’ option ? Here’s what my system stats look like (12.2.0.1 test results) after doing so. (The code to generate the two...
View Articlesystem_stats() hint
Starting from 18.3 Oracle introduced the system_stats() hint, apparently allowing you to set the system statistics for the duration of a query. However the hint didn’t seem to have any effect in that...
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