Optimizer Access Paths: How oracle database works

In this blog, we will explore what is the access path in the Oracle database.

However, before moving to the access path, let’s first understand what is a row source. It is a set of rows that are returned in a step by execution plan. It can be a table or a result of join operations or a view etc.

Access path is how the database retrieves data from a database. It is actually a technique that is being used by a query to retrieve a row from a row source. It accepts only one-row source in unary operations and more than one-row source in binary operations. A Full table scan is a unary operation and a join query is a binary operation.

These access paths are:

  • Full Table Scans
  • Table Access by Rowid
  • Sample Table Scans
  • Index Unique Scans
  • Index Range Scans
  • Index Full Scans
  • Index Fast Full Scans
  • Index Skip Scans
  • Index Join Scans
  • Bitmap Index Single Value
  • Bitmap Index Range Scans
  • Bitmap Merge
  • Bitmap Index Range Scans
  • Cluster Scans
  • Hash Scans

We will explore these access path in details in next few blogs.

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