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db file sequential read

Short Description

The session waits while a sequential read from the database is performed. This event is also used for rebuilding the control file, dumping datafile headers, and getting the database file headers.

Detailed Description​

Simplification: this is a Single Block Read. Yes it's confusing - we know. In this case a single block has been requested and the session is waiting for the read to complete. By far the most common reason to see this wait is a session querying specific blocks within indexes and tables.

How to reduce this wait​

You will see this wait state when using indexes and rowids to access data. To make your database go faster, access less data, so look to your query plans efficiency to ensure optimal execution.

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