Which Oracle access method is the fastest way for Oracle to retrieve a single row?
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Primary key access
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Access via unique index
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Table access by ROWID
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Full table scan
ROWID represents the physical address of a row in the database. Access by ROWID is fastest because it goes directly to the physical location without any index lookup or searching. Index-based methods require additional traversal, while full table scans are slowest.
Accessing a row directly by its ROWID is the fastest retrieval method because the ROWID encodes the exact physical location (file, block, and row number) of the row, letting Oracle go straight to it without any index lookup or scan. Primary key and unique index access still require traversing an index structure first to find the ROWID, adding an extra step compared to direct ROWID access.