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by Craig Shallahamer Get the book here |
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Craig Shallahamer's Blog
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. ------------------------------- This begs the question, "What exactly is recursive SQL?" Most DBAs consider recursive SQL to be any SQL that a DBA or application developer did not create. For example, a DBA may submit this statement: Oracle then takes this nonrecursive statement and dynamically creates the SQL necessary to insert rows into the data dictionary tables, such as tab$ and col$. This dynamically created SQL is indeed recursive SQL. However, consider the SQL shown in the following trace file snippet. The true Oracle definition of recursive SQL is any SQL with a depth greater than zero. Notice the preceding PL/SQL entry has a depth of zero (dep=0) and therefore is officially deemed nonrecursive SQL. However, notice what happens when the select statement is run 500 times: 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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