Querying the dba_hist_sys_time_model to get historical data

This quick post is mainly¬†for myself… I will certainly use it for reference in the future.

Debugging problems due to adaptive dynamic sampling and in general adaptive features sometimes needs to get historical data about, e.g., parse time.

In order to get this information you may need to query the view DBA_HIST_SYS_TIME_MODEL (take care, it needs Diagnostic Pack license!)

You can use this query as an example.


In this specific example, it shows the “parse time elapsed”, the “DB time” and the percentage parse/dbtime, along with the value of the parameter “optimizer_adaptive_features“. You can use it to check if changing the parameters related to adaptive dynamic sampling improves or not the parse time.

The output will be something like this:



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Oracle ACE Director and Computing Engineer at CERN
Ludovico is an Oracle ACE Director, frequent speaker and community contributor, working as Computing Engineer at CERN, the European Council for Nuclear Research, in Switzerland.

One thought on “Querying the dba_hist_sys_time_model to get historical data

  1. Pingback: Querying the dba_hist_sys_time_model to get historical data - Ludovico Caldara - Blogs - triBLOG

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