15.00 - Predicates That Invoke Full-Table Scans - Teradata Database

Teradata Database Design

prodname
Teradata Database
vrm_release
15.00
category
User Guide
featnum
B035-1094-015K

Predicates That Invoke Full‑Table Scans

The following search conditions typically invoke a full‑table scan of the base table or of a secondary index subtable when used as a HAVING or WHERE clause condition because they do not specify a specific value or set of values.

 

Some Teradata Database indexes can optionally be stored in the order of their values as well as in the more standard hash order. If a value-ordered index is defined on the column that satisfies a range predicate from this list, then a full‑table scan is not necessary to satisfy the condition and the Optimizer merely scans a subset of the value-ordered index subtable instead. Furthermore, for tables and join indexes defined with a partitioned primary index, row partition elimination can limit a full‑table scan to just those partitions that are not eliminated.