2.11 Describe a tid scan
Key points
- A TID scan can only be used to locate a single row. You can, however,
issue a query in which multiple TID scans are executed to locate several rows
(each scan returns a single row, and a union is performed over all of the
scans).
- A row is accessed directly using the physical address (TID).
- The I/O cost for a TID scan is equal to one I/O.
- When you use a TID function, you can assume that the optimizer will
choose a TID scan. Please refer to the ALLBASE/SQL Reference Manual
for more information about TID functions.
Page last updated on November 29, 1995
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