Virtual / NOSEGMENT / Fake Indexes

Virtual Indexes (aka NOSEGMENT Indexes or Fake Indexes) are useful to check whether the creation of an Index affects the execution plan with out having to create the actual index. Virtual index is just a definition without a physical index segment so it does not consume disk space. Additionally, virtual index is available to a …

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Optimizer Index Access Paths

Access paths are ways in which data is retrieved from the database. In general, index access paths should be used for statements that retrieve a small subset of table rows, while full scans are more efficient when accessing a large portion of the table. Online transaction processing (OLTP) applications, which consist of short-running SQL statements …

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