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September | 2012 | Oracle DBA – Tips and Techniques
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Why do my execution plans not change after gathering statistics? – A look at Rolling Cursor Invalidations

  • Posted by Gavin Soorma
  • On September 21, 2012
  • 0 Comments
In releases prior to Oracle 10g, the gathering of statistics using DBMS_STATS resulted in immediate invalidations of dependent cached cursors. This was true unless NO_INVALIDATE parameter of the DBMS_STATS command was set to TRUE. It was felt that gathering of statistics could actually have a negative impact on performance because of the fact that invalidation […]
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 5

CURSOR_SHARING=SIMILAR and FORCE – some examples

  • Posted by Gavin Soorma
  • On September 21, 2012
  • 2 Comments
The CURSOR_SHARING parameter basically influences the extent to which SQL statements (or cursors) can be shared.  The possible values are EXACT which is the default value and SIMILAR and FORCE. The official definitions of SIMILAR and FORCE are: cursor_sharing=similar: “Causes statements that may differ in some literals, but are otherwise identical, to share a cursor, […]
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 2

A look at Parsing and Sharing of Cursors

  • Posted by Gavin Soorma
  • On September 21, 2012
  • 0 Comments
Parsing is the first stage in processing a SQL statement – the other two being Execute and Fetch stages. Parse once – execute many is a very important performance tuning goal. What does parsing involve Syntax check – is the SQL statement syntactically correct Semantic check – is the SQL statement meaningful or semantically correct. […]
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 2

Migrating the 11i E-Business Suite database to Linux

  • Posted by Gavin Soorma
  • On September 18, 2012
  • 0 Comments
This note describes the process used to migrate the EBS Release 11i (11.5.10.2) 10g R2 database from a Solaris platform to a Linux 64 bit platform. As part of the Release 12 upgrade preparation, rather than perform  a Solaris/Linux platform migration and 11i to R12.1.3. upgrade at the same time, we are relocating the database […]
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