ODP.NET And Entity Framework Exhibit Poor Performance Selecting From Large Table With Unique Index

(Doc ID 1496533.1)

Last updated on JULY 05, 2017

Applies to:

Oracle Data Provider for .NET - Version 11.2.0.3 and later
Microsoft Windows (32-bit)
Microsoft Windows x64 (64-bit)

Symptoms

When using ODP.NET and Entity Framework you may execute SELECT statements containing STRING bind parameters that exhibit poor performance against large tables.  The poor performance is due to INDEXES not being used as described below:

1.  Create a table and populate it with data.

If you check the Explain Plan, you will see that the UNIQUE key constraint is NOT used.

 

Cause

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