From time to time I have to fight against long parses. In this post I would like to share with you what happened to a customer of mine while upgrading from 9.2.0.7 to 10.2.0.3 (10.2.0.4 was not yet available at that time). The parse of a complex SQL statement took 5 seconds in 9.2.0.7. Not […]
In the paper SQL Profiles (page 22) I described the data dictionary tables where the hints belonging to SQL profiles are stored. For example, with the following query it is possible to display the hints associated to the SQL profile named opt_estimate. SQL> SELECT attr_val 2 FROM sys.sqlprof$ p, sys.sqlprof$attr a 3 WHERE p.sp_name = […]
It happened to me several times to being asked about the mysterious full table scan in CONNECT BY operations. In this post I would like to share with you some of the information I wrote about it in my book (pages 233 to 236) . The operation CONNECT BY WITH FILTERING is used to process […]