5.1.2 About index scans

An index scan uses a B-tree index or text index to evaluate the search conditions and retrieves from data pages all rows that satisfy the search conditions. An index scan is run in the following cases:

• B-tree indexes or text indexes are defined in the table, and a search condition is specified that can effectively use these indexes.

• A B-tree index or text index that can be used for retrieval is specified in the index specification.

The following figure shows an example of an index scan.

Figure 5‒2: Example of an index scan

Explanation:

This example uses B-tree index IDX_C1C2 to evaluate the search conditions and accesses a data page to retrieve the column C3 values.

If range indexes are defined for the table, the range indexes might also be used.

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