Tagged Content List
  • Blog Post: Parallel Full Table Scans Do Not Always Perform Direct Reads

    Even though in general parallel full table scans performs direct reads, some exceptions exist. The aim of this post is to show such an exception. For test purposes I build in my own schema a copy of the SH.SALES table (the one distributed by Oracle with the demo schemas…). On that table I build an ...
  • Blog Post: Parallel Processing With Standard Edition

    As clearly stated in the Licensing Information guide, all features related to parallel processing (parallel backup and recovery, parallel query/DML, parallel statistics gathering, parallel index build/scans, parallel Data Pump export/import, in-memory parallel execution, parallel statement queuing and...
  • Blog Post: Exadata Storage Server and the Query Optimizer – Part 3

    In the first and second post of this series I shared with you some basics about smart scan and gave some details about projection and restriction. The aim of this post is to cover the third basic technique: join filtering. Join filtering is not something specific to the Exadata Storage Server. In fact...
  • Blog Post: Does the Query Optimizer Cost PX Distribution Methods?

    The short answer to this question is “yes”, it does. Unfortunately, the distribution costs are not externalized through the execution plans and, as a result, this limitation (yes, it is really a limitation in the current implementation, not a bug) confuses everyone that carefully look at...
  • Blog Post: System Managed Extent Size – 11g Improvements

    Oracle Database provides two extent management options: locally managed and dictionary managed. Today, when creating a new database, most DBAs use the former for all tablespaces. This is a good thing. What is less obvious is the choice between uniform extent size and system managed extent size. Both...
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