How to Read an Execution Plan

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Eine kurze Einführung von Chris Saxon zu Execution Plans:
https://blogs.oracle.com/connect/post/how-to-read-an-execution-plan

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PGA unter Oracle 11g

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aus der Doku: Quelle: http://download.oracle.com/docs/cd/E11882_01/server.112/e16638/memory.htm#PFGRF94351 7.5 PGA Memory Management For complex queries (for example, decision support queries), a big portion of the run-time area is dedicated to work areas allocated by memory intensive operators, such as the following: * Sort-based operators, such as ORDER BY, GROUP BY, ROLLUP, and window functions * Hash-join * Bitmap merge * Bitmap create * Write buffers used by bulk load operations Sizing: A) Ideally, the size of a work area is big enough that it can accommodate the input data and auxiliary memory structures allocated by its associated SQL operator. This is known as the optimal size of a work area. B) When the size of the work area is smaller than optimal, the response time increases, because an extra pass is performed over part of the input data. This is known as the one-pass size of the work area. C) Under the one-pass threshold, when the size of a work area is far too small compar
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trunc(sysdate) - nette Spiele mit dem Datum

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Datapump - Verzeichnis erstellen

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