Craig Shallahamer's Blog
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You were brought to this page based on an internet search
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The text below is an except from the book,
Oracle Performance Firefighting, written by
Craig Shallahamer of
OraPub, Inc.
Figures and tables are not included on this page, only their reference.
To order the book in either print or PDF form, click
here.
©2009, 2010 by Craig Shallahamer. This is copyrighted material.
Please—Out of respect for those involved in the creation of the book and also for
their familes, we ask you to respect the copyright both in intent and deed. Thank you.
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<p>WAITED UNKNOWN TIME: Last wait time is unknown; perhaps instance parameter timed_statistics is false
</p><p>Suppose we wanted to take a closer look at a particular session. Continuing our example based on Figure 2-8 and Figure 2-9, look closely at Figure 2-10. This is a very simple script based on v$session_wait. In this example, we caught session 205 in the middle of a wait and the details are exposed. Figure 2-10 clearly shows session 205 is currently waiting for an operating system multiblock read to complete. And we also know that 16 blocks are being requested (P3), the first block's file number is 4 (P1), and its block number is 12925 (P2).
</p><p>Figure 2-10. This script is based on the v$session_wait view. This is easy to tell because the output contains the parameter columns. Session 205 is currently waiting for the operating system to retrieve 16 blocks.
</p>
©2009, 2010 by Craig Shallahamer. This is copyrighted material.
Please—Out of respect for those involved in the creation of the book and also for
their familes, we ask you to respect the copyright both in intent and deed. Thank you.
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