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In the previous post we discussed about the Parent & Child Cursors in Oracle and how do they work or shared. To get into deeper, Oracle controls the sharing of cursors with parameter called cursor_sharing. It has three values EXACT SIMILAR FORCE In this post we will create a table which has some records with […] What are PARENT AND CHILD CURSORS IN ORACLE A cursor is a memory area in library cache allocated to a SQL statement which stores various info about the SQL statement like its text, execution plan, statistics etc. Each SQL statement has One Parent cursor One or more child cursors PARENT CURSOR It […] Adaptive cursor sharing as you all aware , This was introduced in 11gR1 to address issues related to bind variable peeking. See support note 740052.1 and documentation for details. You may have weird behaviors of your sql’s after upgrade to 11g , this may be due to no proper testing done, or optimizer features […] The following is the direct extract from the documentation on adaptive cursor sharing. The adaptive cursor sharing feature enables a single statement that contains bind variables to use multiple execution plans. Cursor sharing is "adaptive" because the cursor adapts its behavior so that the database does not always use the same plan for […] If you are experiencing the log file sync wait after an upgrade to 11.2.0.3 and most importantly that as there are no other symptoms of issues with I/O or in other areas, the problem could be with excessive switching between post/wait and polling wait methods. While writing previous post, came across the another interesting note […] Oracle 10g provides the Automatic Worload Repository. The AWR is a repository of performance information collected by the database to aid in the tuning process for DBAs. The main focus for the Oracle database in version 10g is self-manageability. AWR is the place where the data to aid in self-management is stored. WHAT DOES […] All, I have got a chance to speak about this nice cool feature in an other practical demo session to my colleagues, but few questions on the same remind to post and read something on this. Typically as usual my post flow, What, How, How to, Important note? What is SQL Monitoring? If a query […] Hello, In case you want to know more about Oracle Wait events please read here What are the causes for those wait event and how you can troubleshoot and resolve the same was neatly written in this document. This document is very good, structured (apologies I do not remember the source and who written it, […] We all know that Oracle Optimizer use object statistics to determine the cost of accessing that object. What if, if that object has missed statistics or the columns or the Hence Oracle introduced Dynamic sampling in 9i and has changed significantly through 11g. Definition:- Dynamic sampling augments missing or insufficient optimizer statistics. Using dynamic sampling […] What is cardinality? CBO estimate of the number of rows produced by a row source or combination of row sources. What are different types of cardinality? Cardinality Cardinality represents the number of rows in a row set. Here, the row set can be a base table, a view, or the result of a join […] |
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Oracle 23c New Features for DBA's
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